SHELLAC

SHELLAC

CAS Number: 9000-59-3
EC Number: 232-549-9
MDL number: MFCD03101446
Molecular Formula: C30H50O11

Shellac is a resin secreted by the female lac bug on trees in the forests of India and Thailand. 
Shellac is processed and sold as dry flakes and dissolved in alcohol to make liquid shellac, which is used as a brush-on colorant, food glaze and wood finish. 
Shellac functions as a tough natural primer, sanding sealant, tannin-blocker, odour-blocker, stain, and high-gloss varnish. 

Shellac was once used in electrical applications as Shellac possesses good insulation qualities and Shellac seals out moisture. 
Phonograph and 78 rpm gramophone records were made of Shellac until they were replaced by vinyl long-playing records from 1948 onwards.
From the time Shellac replaced oil and wax finishes in the 19th century, shellac was one of the dominant wood finishes in the western world until Shellac was largely replaced by nitrocellulose lacquer in the 1920s and 1930s.

Etymology:
Shellac comes from shell and lac, a calque of French laque en écailles, 'lac in thin pieces', later gomme-laque, 'gum lac'. Most European languages (except Romance ones and Greek) have borrowed the word for the substance from English or from the German equivalent Schellack.

Shellac is a natural bioadhesive polymer and is chemically similar to synthetic polymers. 
Shellac can thus can be considered a natural form of plastic.
With a melting point of 75 °C (167 °F), Shellac can be classed as a thermoplastic; used to bind wood flour, the mixture can be moulded with heat and pressure.

Shellac scratches more easily than most lacquers and varnishes, and application is more labour-intensive, which is why Shellac has been replaced by plastic in most areas. 
But damaged shellac can easily be touched up with another coat of shellac (unlike polyurethane, which chemically cures to a solid) because the new coat merges with and bonds to the existing coat(s). 

Shellac is much softer than Urushi lacquer, for instance, which is far superior with regard to both chemical and mechanical resistance.
Shellac is soluble in alkaline solutions such as ammonia, sodium borate, sodium carbonate, and sodium hydroxide, and also in various organic solvents. 
When dissolved in alcohol (typically denatured ethanol) for application, shellac yields a coating of good durability and hardness.

Upon mild hydrolysis shellac gives a complex mix of aliphatic and alicyclic hydroxy acids and their polymers that varies in exact composition depending upon the source of the shellac and the season of collection. 
The major component of the aliphatic component is aleuritic acid, whereas the main alicyclic component is shellolic acid.
Shellac is UV-resistant, and does not darken as Shellac ages (though the wood under Shellac may do so, as in the case of pine).

Shellac, commercial resin marketed in the form of amber flakes, made from the secretions of the lac insect, a tiny scale insect, Laccifer lacca (see lac). 
Shellac is a natural thermoplastic; that is, a material that is soft and flows under pressure when heated but becomes rigid at room temperature. 
This property makes Shellac useful either by itself or in combination with such fillers as flaked mica and asbestos in manufactured molding compositions, used for producing molded articles such as buttons.

Shellac is an ingredient in many products, including abrasives, sealing wax, hair sprays, and cake glazes. 
Shellac was formerly used, along with fine clay or other filler, to mold phonograph records, but, after the early 1930s, synthetic thermoplastics, particularly vinyl resins, gradually replaced Shellac.
Alcohol solutions of shellac, also called simply shellac, are used as varnishes for priming and finishing furniture, floors, and various wood articles and as an intermediate in nitrocellulose lacquers. 

Alkali emulsions of shellac are used to make self-polishing waxes, stiffeners for felt hats, cements, and sealers.
Shellac is the only finish on the market that is all natural and made from a renewable resource. 
Shellac is made from the hard resin shells created by the Lac bug and deposited on trees in India and Thailand. 
Shellac is processed into flakes and added to denatured alcohol, which comes from crop plants rather than finite petroleum resources.

Shellac is alcohol-based and meets all federal and state air quality standards.
Shellac was a product of choice for dyes, flooring, woodwork and furniture. 
Shellac's use as a wood finish flourished in America from the 1600s through the first half of the 20th century. 
Most woodwork in historic houses built before 1930 had a shellac finish. 
Shellac was popular due to its ease of application and repair, fast drying time, quick clean-up, high durability and color control. 

Shellac comes into two different varieties: amber and clear. 
Amber is the natural color of shellac; clear shellac has been bleached.
However, by the middle of the 20th century, most contractors and building owners had switched from shellac finishes to cheap petroleum-based wood varnishes, lacquers and urethanes. 
If your original shellac finish has been covered with a petroleum-based finish, you cannot easily switch back to a shellac finish. 

You cannot put a shellac finish over a modern polyurethane finish.
Shellac is an all purpose sealant and finish that is durable, time tested, and so non-toxic it is edible. 
Shellac is environmentally friendly, renewable, and capable of incredibly deep rich finishes that are organically and aesthetically compatible with all woods. 
Shellac can be used alone, with traditional natural finishes and coatings, and with modern synthetic mixtures. 
Shellac consists of a resin which is the secretion of the female lac beetle and the solvent ethyl alcohol. 

The lac beetle (Laccifer Lacca) is found in southwest Asia, primarily India. 
The beetles feed on the tree sap of three specific trees: Palash, Kusum, and Ber or Indian Plum. 
During the life and egg lying cycles of the female beetle lac is secreted to protect the beetle and the eggs. 
The branches are then harvested and the lac resin scraped off. 
This is called sticklac and at this stage it is still very impure with a lot of contaminants and debris.

Additional filtering and washing removes most of the foreign debris and gives youseedlac. 
At this point the resin becomes a usable finish when dissolved in alcohol. 
The seedlac is then heated and filtered through cloth and deposited on to a cool metal surface in small discs which are called button lac.
Today, commercial shellac comes from plantations in India and Thailand, which together produce 1,700 metric tons of the substance every year.

Shellac is a refined version of lac, a resin secreted by lac insects.
There are many resultant varieties of shellac. 
These variations are created by the type of tree initially involved, the area, the beetles, and the variations of filtering process which consists primarily of heat or bleaching. 
The different tree sources and variations of filtering and manufacture can give you a wide range of color from very pale and colorless to dark garnet. 

Another variation is whether or not the inherent natural wax is removed. 
The amount of wax can determine clarity and influence the hardness of the final film.
There is a great deal of confusion about the term shellac. 
Shellac can be traced back to the Sanskrit word lakh (laksa) which means 100,000. 
This relates to the vast number of beetles needed to infest the trees in order to produce significant amount of resin. 

Shellac has been used in India, Southeast Asia, and China for many centuries. 
Written accounts go back 3,000 years but Shellac was probably in use even earlier.
There is evidence and accounts of shellac being introduced to Europe as early as the thirteenth century. 
Shellac's use became fairly widespread beginning in the seventeenth century. 
This was the result of the opening and expanding trade routes to the Far East due to the advancement of the shipping industry. 

At the same time there was expanding importation of exotic woods from both the Far East and the Americas. 
The increased prominence of exotic wood veneers such as mahogany and satin wood required a clear coating that would enhance and protect while not covering up the subtle colors and grain patterns. 
Shellac was perfect for this.
The manufacture of imitation lacquer ware (Chinoiserie, japanning), became very profitable. 
Pigmented shellac became one of the key ingredients in creating an equivalent to urushi lacquer ware. 

Confusion arose due to the commonality of the names, shellac was  often called just lac during this time, and the similarity of the appearance of the final finishes. 
But the two finishes are very different in origin, chemical makeup, and susceptibility to different conditions and solvents. True urushi lacquer is an extremely hard, water proof, heat resistant natural polymer that forms a hard non-reversible film through oxidation. 

Shellac is a natural bioadhesive polymer that hardens through evaporation and is susceptible to water, heat, and is reversible through the reintroduction of its main solvent alcohol.
From the mid eighteenth century to the early twentieth century in Europe and America shellac was considered the prime coating for fine furniture and woodwork. 
But shellac was also very popular as a wood sealant and coating and was used at any level when Shellac was available. 
The ultimate expression of shellac finish is French polish.

French polish is the method of application rather than the material, though there are premixed usually high quality de-waxed shellacs that are sold as French polish.
In French polishing the shellac is applied with a cotton pad which consists of fad or cotton wadding wrapped inside a rubber which is typically a cotton cloth. 
The shellac is injected into the wadding and applied in thin coats by rubbing the rubber over the surface. 

The method is very labor intensive, requires drying between layers, is very tricky to master, and has about as many recipes, methods, and tricks as there are French polishers.
The final finish can be brought up to a closed grain, clear, mirror like finish that is wonderfully warm, deep, and complimentary to wood. 
While the finish is susceptible to damage from the exposure to moisture and heat it can be readly repaired by repadding with alcohol or additional shellac.

This is very different from most synthetic catalyzed polymer coatings that are unworkable once they chemically crosslink.
Shellac was replaced in many uses in the 1920s and 1930s due to the popularization of nitrocellulose lacquer and later by the subsequent development of synthetic chemical spray finishes. 
These spray finishes have much greater short term durability due to their chemical cross linking which gives them greater resistance to moisture, heat, and impact. 
This increase in "strength" and chemical longevity is balanced by their irreversibility. 

This means they are very hard to repair. 
This means any damage that has to be repaired requires stripping. 
If the piece or construction is of a fine wood, this means you will lose any patina. 
As wood is always going to shrink and swell due to relative humidity changes, these finishes are susceptible to eventual cracking and the only treatment is total replacement through chemical stripping and refinishing. 
Shellac is very useful as a sealant since Shellac will stick to almost anything. 

While susceptible to moisture Shellac is an extremely good barrier to moisture vapor and odors. 
Even when dry, Shellac has a degree of plasticity that will allow some movement and reduce cracking. 
Shellac is UV light resistant and does not react to most solvents other than alcohol.
Shellac is a coating or glaze derived from the hardened, resinous material secreted by the lac insect, much like honey from a bee. 
Shellac in its raw form, known as “lac resin,” along with lac wax and lac dye, is produced in Southeast Asia. 

India is the largest producer in the world, yielding 18,000 metric tons of unrefined lac resin annually.
Approximately 85% of India’s crop is exported, mostly to European countries, Egypt, and the United States.
all forms of shellac, (even “orange shellac” or “lemon shellac” which may connote non-animal origins), are derived from lac resin.
Shellac is the resinous exudate produced by the female Indian "lac" bug, an insect that spends its whole life attached to a tree, sucking its sap and converting it into the familiar sticky substance that has long been used to provide a glossy protective coating on wood. 

Shellac takes about 100,000 insects to produce a pound of red-tinged resin. 
Shellac is a resinous product obtained from the secretion of the female “lac bug” (Kerria lacca) on trees, mostly in the forests of India and Thailand. 
The dry flake processed shellac is dissolved in ethanol to obtain liquid shellac, which is used as a brush-on colorant, food glaze, and wood finish. 

Although French Polish is the general term used for all types of shellac polish, Shellac is also a Shellac Polish colour in Shellac's own right. 
There are many blends of shellac polish that have been developed over the years.

How Shellac Is Made:
Shellac has a unique manufacturing process. 
Shellac's derived from a resin secreted by insects native to forests in Thailand and India. 
The secretion is scraped from the bark of trees and then processed to form small, light-brown, or orange flakes. 
The flakes are mixed with alcohol to create a finish.

Lac is the name given to the resinous secretion of the tiny lac insect (Laccifer lacca) which is parasitic on certain trees in Asia, particularly India and Thailand. 
This insect secretion is cultivated and refined because of the commercial value of the finished product known as shellac. 
The term shellac is derived from shell-lac (the word for the refined lac in flake form), but has come to refer to all refined lac whether in dry or suspended in an alcohol-based solvent.

Shellac originates with the lac beetle, mainly in India and Thailand. 
Contrary to myth, Shellac's not made from beetle poop but female-beetle secretions deposited on tree branches. 
Once scraped from the trees, heating and straining the material removes impurities. 
Shellac's then rolled out into sheets to cool and dry. 
Breaking those sheets yields flakes, while further heat processing creates buttons. 

Each form dissolves in denatured alcohol, creating a liquid finish.
Depending on the type of tree upon which the beetles feast, natural shellac colors range from a dark garnet through brown, red, orange, and yellow. 
Amber and orange shellacs impart a warm, rich look to dark woods such as walnut, cherry, and mahogany. 
Bleached shellac imparts clear, light-blonde and super-blonde shades. 
You can tint shellac with dye for an unlimited range of colors, useful when matching an existing finish or repairing a damaged one.

Though not as durable as polyurethane or varnish, shellac proves much easier to repair. 
All shellac products produce a gloss sheen.
Shellac is generally made from two ingredients, raw seed lac and ethyl alcohol. 
In fact, most companies want to purify shellac as completely as possible—impurities from the bug, the cocoon etc. are removed, as are natural waxes. 

Shellac is generally shipped in dry or flaked form and is re-moisturized with an alcohol solvent, generally denatured alcohol. 
Some companies add ingredients to lengthen the shelf life of their product but will not reveal these proprietary additives. 
Shellac that is bleached (or made into clear shellac) are dissolved in sodium carbonate and centrifuge to remove insolubles and then bleached with sodium hypochlorite.
Shellac is a refined version of lac, a resin secreted by lac insects. 

Today, commercial shellac comes from plantations in India and Thailand, which together produce 1,700 metric tons of the substance every year.
Lac is secreted by female lac bugs, most commonly of the species Kerria lacca. 
The bugs are actually parasitical and can be hosted by more than 300 species of trees throughout India, Thailand, China, and Mexico.
Among these trees are those in the pea family, Indian jujubes, soapberries, hibiscus species, and the Barbados nut. 
Today, about 90% of lac comes from palash (Butea monosperma), ber (Ziziphus mauritiana), and kusum (Schleichera) trees.

The lac bugs suck sap from the bark, knowingly feeding to death, while simultaneously laying up to 1,000 eggs over a five-week period. 
The sap undergoes a chemical transformation in their bodies so that when it's secreted, it hardens on contact with the air and creates a protective shell around the eggs. 
That hard shell is what's harvested to make shellac. 

Plantation workers cut off entire chunks of branches coated in the stuff—the branches are a product themselves, called sticklac—and send them to refineries to be scraped off, ground down, and screened to remove dead insects and wood debris.
After rinsing, drying, being melted into a liquid, and drying again, the amorphous substance is liquified using a solvent (usually ethyl alcohol).

Lac naturally has a red-orange tint that is somewhat removed during the refining process. 
Still, the final shellac product is not entirely clear and must be mixed with sodium hypochlorite—pure bleach—to remove residual color. 
The resulting white powder is preferred for cosmetics over the original red-orange lac. 
The trees on which lac bugs most commonly feed grow profusely in Thailand and India. 
The ethyl alcohol often used to liquify shellac is considered a volatile organic compound. 

A resinous substance excreted by the female of the lac insect, Laccifer lacca, native to India. 
The insects primarily deposit lac on the twigs and soft new branches of several varieties of soapberry and acacia trees, such as the sacred fig, Ficus religiosa, found in India, Thailand, Myanmar (Burma), and elsewhere in southeast Asia. 
Lac was used as early as about 1200 BCE in India. 
Shellac and Lac dye were imported to Europe in the 17th century. 

The resin coated twigs, also called sticklac, undergoes several processing steps to extract useful components. 
The raw lac is washed, heated and drawn out into thin sheets. 
Once cooled, the shellac is broken into small flakes for sale as flake shellac. 
The color of shellac ranges from a pale yellow to a deep red. 
Shellac is soluble in alcohol and is used to obtain the high gloss on French polished furniture. 

Shellac is also used as a protective coating for plaster molds and casts. 
In the 19th century, shellac was filled with wood flour and used for molded composition products such as buttons, picture frames, Daguerreotype and Ambrotype cases, and gramophone records. 
Black pigmented, mineral-filled shellac was used for 78 rpm phonograph records, mirror frames, brooches, and dressing table sets. 
Shellac was often adulterated with Rosin.

Shellac is a versatile, non-toxic wood finish that enhances the natural grain while adding smoothness without the plastic-like qualities of polyurethane or lacquer. 
Made from flakes of resin secreted by lacs (insects native to Asia) and dissolved in alcohol, shellac is typically available in clear or amber but can also be tinted to bring out a range of hues from golden oak to dark mahogany. 
Shellac’s readily available at home centers, goes on easily, and dries quickly.

Shellac is a natural resin that’s derived from the secretions of the Lac bug–an insect that feeds off trees indigenous to India and Thailand. 
The secretions–in the form of cocoons–are gathered from the trees and refined into dry flakes or buttons, which are dissolved in alcohol for application. 
Cans of premixed shellac are commonly available, but you can also purchase “dry shellac” in flake or button form to mix yourself.

Many finishers prefer to mix their own shellac to ensure that it is fresh. Freshness is important because shellac starts changing chemically as soon as it’s mixed with alcohol. 
Shellac is a resin secreted by the female lac bug, Kerria lacca (Order Hemiptera, Family Coccidae) on trees in the forests of India and Thailand. 
The insect secretes resin forming tunnel-like tubes as it traverses the branches of trees. 

This insect is in the same family as the insect from which cochineal is obtained. 
The resin is collected, processed and sold as dry flakes that can be dissolved in ethyl alcohol to make liquid shellac. 
Shellac forms a durable natural coating that is useful as a primer, sanding sealant, tannin-blocker, odor-blocker and high-gloss varnish.
Shellac is graded by several variables; the two most common are its wax content and color. 

The color of shellac ranges from pale yellow (“platina”) to a dark reddish-brown (“garnet”), with all shades of brown, yellow, orange and red in between. 
The color is influenced by the sap of the tree that the lac bug lives on and the time of harvest. 
Historically, the most commonly-sold shellac is called “orange shellac.”
Shellac naturally contains 3 to 5% wax, called “shellac wax.” 
The lower the amount of wax, usually the better the grade of shellac. 

Some grades of shellac are de-waxed. 
Dewaxed shellac has better transparency and moisture resistance. 
The wax in shellac reduces the clarity of the finish and the molecular weight of the shellac resin, making shellac less resistant to water. 

However, dewaxed shellac has a much shorter shelf life after mixing shellac with alcohol (about 6 months).
Shellac is a natural product made from the excretions of the lac beetle. 
Shellac comes in colors that range from dark reddish brown to a golden amber color depending on the time of harvest and degree of processing.

USES and APPLICATIONS of SHELLAC:
*SHELLAC IS USED:
-In the tying of artificial flies for trout and salmon, where the shellac was used to seal all trimmed materials at the head of the fly.
-In combination with wax for preserving and imparting a shine to citrus fruits, such as lemons.
-In dental technology, where it is occasionally used in the production of custom impression trays and (partial) denture production.

-As a binder in India ink.
-For bicycles, as a protective and decorative coating for bicycle handlebar tape, and as a hard-drying adhesive for tubular tyres, particularly for track racing.
-For re-attaching ink sacs when restoring vintage fountain pens, the orange variety preferably.
-For fixing pads to the key-cups of woodwind instruments.

-For Luthier applications, to bind wood fibres down and prevent tear out on the soft spruce soundboards.
-To stiffen and impart water-resistance to felt hats, for wood finishing and as a constituent of gossamer (or goss for short), a cheesecloth fabric coated in shellac and ammonia solution used in the shell of traditional silk top and riding hats.
-For mounting insects, in the form of a gel adhesive mixture composed of 75% ethyl alcohol.

-As a binder in the fabrication of abrasive wheels, imparting flexibility and smoothness not found in vitrified (ceramic bond) wheels. 
'Elastic' bonded wheels typically contain plaster of paris, yielding a stronger bond when mixed with shellac; the mixture of dry plaster powder, abrasive (e.g. corundum/aluminium oxide Al2O3), and shellac are heated and the mixture pressed in a mould.

-In fireworks pyrotechnic compositions as a low-temperature fuel, where it allows the creation of pure 'greens' and 'blues'- colours difficult to achieve with other fuel mixes.
-In Jewellery; shellac is often applied to the top of a 'shellac stick' in order to hold small, complex, objects. 
By melting the shellac, the jeweller can press the object (such as a stone setting mount) into it. 
The shellac, once cool, can firmly hold the object - allowing it to be manipulated with tools.

-In watchmaking, due to its low melting temperature (about 80–100 °C (176–212 °F)), shellac is used in most mechanical movements to adjust and adhere pallet stones to the pallet fork and secure the roller jewel to the roller table of the balance wheel. 
Also for securing small parts to a 'wax chuck' ( faceplate ) in a watchmakers' lathe.
-In the early twentieth century, it was used to protect some military rifle stocks.
-In Jelly Belly jelly beans, in combination with beeswax to give them their final buff and polish.

-In modern traditional archery, shellac is one of the hot-melt glue/resin products used to attach arrowheads to wooden or bamboo arrow shafts.
-Sanding sealer, is a solution of shellac dissolved in alcohol widely sold to seal sanded surfaces, typically wooden surfaces before a final coat of a more durable finish. 
Similar to French Polish but more dilute.

-As a topcoat in nail polish (although not all nail polish sold as "shellac" contains shellac, and some nail polish not labelled in this way does)
-In sculpture, to seal plaster and in conjunction with wax or oilsoaps, to act as a barrier during mold-making processes
-As a dilute solution in the sealing of harpsichord soundboards, protecting them from dust and buffering humidity changes while maintaining a bare-wood appearance.
-Filming and fixing agent. 
-Shellac is a resin-like substance produced by Laccifer (Tachardia) lacca insects.

*HISTORICAL USES of SHELLAC:
-In the early- and mid-twentieth century, orange shellac was used as a one-product finish (combination stain and varnish-like topcoat) on decorative wood panelling used on walls and ceilings in homes, particularly in the US. 
In the American South, use of knotty pine plank panelling covered with orange shellac was once as common in new construction as drywall is today. 
Shellac was also often used on kitchen cabinets and hardwood floors, prior to the advent of polyurethane.

-Until the advent of vinyl, most gramophone records were pressed from shellac compounds. 
From 1921 to 1928, 18,000 tons of shellac were used to create 260 million records for Europe. 
In the 1930s, Shellac was estimated that half of all shellac was used for gramophone records. 
Use of shellac for records was common until the 1950s and continued into the 1970s in some non-Western countries.

-Until recent advances in technology, shellac (French polish) was the only glue used in the making of ballet dancers' pointe shoes, to stiffen the box (toe area) to support the dancer en pointe. 
Many manufacturers of pointe shoes still use the traditional techniques, and many dancers use shellac to revive a softening pair of shoes.

-Shellac was historically used as a protective coating on paintings.
-Sheets of Braille were coated with shellac to help protect them from wear due to being read by hand.
-Shellac was used from the mid-nineteenth century to produce small moulded goods such as picture frames, boxes, toilet articles, jewelry, inkwells and even dentures. 
Advances in plastics have rendered shellac obsolete as a moulding compound.

-Shellac (both orange and white varieties) was used both in the field and laboratory to glue and stabilise dinosaur bones until about the mid-1960s. 
While effective at the time, the long-term negative effects of shellac (being organic in nature) on dinosaur bones and other fossils is debated, and shellac is very rarely used by professional conservators and fossil preparators today.

-Shellac was used for fixing inductor, motor, generator and transformer windings. 
-Shellac was applied directly to single-layer windings in an alcohol solution. 
For multi-layer windings, the whole coil was submerged in shellac solution, then drained and placed in a warm place to allow the alcohol to evaporate. 

-The shellac locked the wire turns in place, provided extra insulation, prevented movement and vibration and reduced buzz and hum. 
-In motors and generators Shellac also helps transfer force generated by magnetic attraction and repulsion from the windings to the rotor or armature. 
In more recent times, shellac has been replaced in these applications by synthetic resins such as polyester resin. 

-Some applications use shellac mixed with other natural or synthetic resins, such as pine resin or phenol-formaldehyde resin, of which Bakelite is the best known, for electrical use. 
Mixed with other resins, barium sulfate, calcium carbonate, zinc sulfide, aluminium oxide and/or cuprous carbonate (malachite), shellac forms a component of heat-cured capping cement used to fasten the caps or bases to the bulbs of electric lamps.

*CURRENT USES of SHELLAC:
-Shellac is the central element of the traditional "French polish" method of finishing furniture, fine string instruments, and pianos.

-Shellac, edible, is used as a glazing agent on pills (see excipient) and sweets, in the form of pharmaceutical glaze (or, "confectioner's glaze"). 
Because of Shellac's acidic properties (resisting stomach acids), shellac-coated pills may be used for a timed enteric or colonic release. 
Shellac is used as a 'wax' coating on citrus fruit to prolong its shelf/storage life. 
Shellac is also used to replace the natural wax of the apple, which is removed during the cleaning process. 
When used for this purpose, Shellac has the food additive E number E904.

-Shellac is an odour and stain blocker and so is often used as the base of "solves all problems" primers. 
Although Shellac's durability against abrasives and many common solvents is not very good, shellac provides an excellent barrier against water vapour penetration. 
Shellac-based primers are an effective sealant to control odours associated with fire damage.

-Shellac has traditionally been used as a dye for cotton and, especially, silk cloth in Thailand, particularly in the north-eastern region. 
Shellac yields a range of warm colours from pale yellow through to dark orange-reds and dark ochre. 
Naturally dyed silk cloth, including that using shellac, is widely available in the rural northeast, especially in Ban Khwao District, Chaiyaphum province. 
The Thai name for the insect and the substance is "khrang".

*WOOD FINISH USES of SHELLAC:
-Wood finishing is one of the most traditional and still popular uses of shellac mixed with solvents or alcohol. 
This dissolved shellac liquid, applied to a piece of wood, is an evaporative finish: the alcohol of the shellac mixture evaporates, leaving behind a protective film.

-Shellac as wood finish is natural and non-toxic in Shellac's pure form. 
A finish made of shellac is UV-resistant. 
For water-resistance and durability, Shellac does not keep up with synthetic finishing products.

-Because Shellac is compatible with most other finishes, shellac is also used as a barrier or primer coat on wood to prevent the bleeding of resin or pigments into the final finish, or to prevent wood stain from blotching.

-Other interior wood elements such as shelves were commonly stained and finished with shellac. 
-Shellac has been regaining its popularity in recent years. 
The “green revolution” in construction may be one reason for this surge in popularity. 
Shellac is considered a “green” product for the following reasons.

-Shellac is still the best wood finish available because it has blocking powers superior to any other finish. 
These blocking powers include the following:
Shellac blocks odors like pet urine and smoke better than other products. 
Shellac blocks the resin from knots and oily exotic woods, preventing them from seeping out and damaging the finish. 
Shellac blocks silicone contamination. 
Silicone can cause a fisheye effect that makes it difficult to refinish the wood. 

Silicone is used in many modern dusting products. 
The silicone penetrates the wood in small surface cracks that develop over time. 
Once silicone is in the wood, it is difficult to remove. 
The only way to remove fisheye is to lightly sand the area and refinish it, then sand again and finish again, repeating the process until the finish is blended to match the non-contaminated areas.

-In dentistry, shellac from Laccifer lacca is used to make dentures and other dental products. 
-In the pharmaceutical industry, shellac is used as a tablet coating and for other uses. 
-In manufacturing, shellac is used as a finish for furniture, an ingredient in hair spray and in other cosmetics. 
-Although shellac has been used for years in pharmacy, dentistry, and manufacturing, Shellac has fallen into disfavor for some products because Shellac ages over time.

-Coveted for its binding abilities and glossy appearance, the material is present in a range of personal care products and cosmetics. 
-Shellac is used to add shine to nail polish and hair spray, bind mascara, emulsify moisturizers, and protect fragrances from oxidation.
-Shellac can be washed down with alcohol to whatever depth is needed to treat damaged or degraded areas. 
This allows repairs or new finish to be applied without damaging the wood substrate or patina.

-Many lacquers and catalyzed polymer finishes will react with the underlying sizing causing accentuation of the leaf lines or shrinkage that can mar the guilt finish. 
Once shellac has been applied over the gold leaf, additional coatings can safely be applied for added protection without problem. 
-Shellac has GRAS status by the Food and Drug Administration (FDA) which means that Shellac is generally recognized as safe in foods. 
If used as a fruit or vegetable coating, Shellac may be labeled as lac resin or as shellac. 

-Shellac, in one or more of its various forms, (e.g., bleached, dewaxed, etc.), may be found in a wide variety of products including furniture polish and varnish; aluminum foil coating; paper coating; hairspray, shampoos, perfume, mascara and lipstick; printing inks and paints; pharmaceutical tablets; and agricultural fertilizer (slow-release coating for urea). 
-Confectioner’s glaze, the name often used for shellac by candy makers, is composed of approximately 35% shellac (purified lac resin). 
The rest are volatile organic compounds which evaporate off during manufacture.

-In foods, shellac is most commonly used as a coating or glaze on confections, chewing gum, fruit, and coffee beans. 
Lac dye, red like carmine, (another insect product), may be used as a coloring in foods and beverages.
-As a general rule, any hard-coated, shiny candy contains a shellac coating or glaze. 
Shellac may appear on the label under different names. 
The two most common ones in use today are “resinous glaze” or “confectioner’s glaze.” 
In general, all Easter candy (eggs and jelly beans) are coated. Halloween candy (candy corn) is as well.

-The colour can be extracted and used as a dye.
-To make clear shellac, the resin is bleached with hypochlorite.
-Shellac has also been used for a variety of purposes, ranging from stiffening hats to making buttons. 
-The first hair sprays had shellac as their main ingredient, and the original phonograph records were made of this material which is soft and flows when heated, but becomes rigid at room temperature. 

-In the food industry, Shellac is referred to as "confectioner's glaze," and can be used to give a protective, glossy coating to candies, jelly beans and ice cream cones. 
-Since shellac is insoluble in water, Shellac can prevent the food product from drying out by forming a layer impermeable to moisture. 
Citrus fruits and avocados are sometimes shellacked for this reason. 

-Shellac is very useful as a sealer coat and is an excellent medium for repair work because of Shellac's compatibility with other types of finishes. 
-Shellac functions as a tough natural primer, sanding sealant, tannin blocker, odor blocker, stain, and high-gloss varnish. 
-Shellac may be used on an object for a Shellac's good insulation qualities, sealing out moisture.
-The biopolymer is thermoplastic in nature and provides good adhesion to other objects.

-An alcoholic (ethanol or methanol) solution of shellac yields a coating with good durability and hardness. 
-Furthermore, this coating does not darken as Shellac ages because shellac is an UV-resistant material. 
-Shellac is important in the fields of surface coatings and paints due to the formation of smooth, hard, and glossy film with high adherence.

-Because of its brittleness and poor chemical resistance properties, shellac has limited use in paints for building surfaces. However, maleated shellac, a product of maleic anhydride reacted shellac and acrylic resin-based coating, exhibited good adhesion finish, smoothness and lack of flaking on the surfaces, and good water and chemical resistance for applied substrates such as plaster of Paris, cement, and limed surface.

-In shellac is used for tooth sensitivity, as well as to make dentures and other dental products. 
-In the pharmaceutical industry, shellac is used as a tablet coating and for other uses.
-In manufacturing, shellac is used as a finish for furniture, an ingredient in hair spray, and in other cosmetics. 
-In foods, shellac is used as a coating or color.
-Shellac is used for its clear coating properties and as a natural "glue".

-Shellac is composed of hydroxyaliphatic acids and alicyclic acids. 
-Shellac has been used in the pharmaceutical industry as a tablet coating, often for enteric coating on tablets. 
-In the cosmetics industry, shellac has been used in mascara, hair spray, nail polish and eyeliner. 
-Traditionally, shellac has been used in the furniture industry as a wood or paint sealant.

-Shellac is primarily used as a wood sealer and finisher today.
Shellac has the great advantage of being soluble in ethyl or denatured alcohol, an environmentally-safe solvent. 
Alcohol solvents also render shellac a quick dry—shellac coatings on wood generally dry in about 45 minutes, as opposed to oil finishes which take many hours to dry. 
In addition, shellac does not fade in sunlight or oxidize over time. 

-Industrial uses for shellac include floor polishes, inks, grinding wheels, electrical insulations, and leather dressings. This natural, resinous sealer is non-toxic and is Federal Drug Administration (FDA) approved for use to coat candies, pharmaceuticals, fruit, and baby and children's furniture.

-Shellac is available at most hardware or paint stores in clear or white shellac or orange shellac, which imparts an orange-red tint to natural wood. 
Other tints derive their color not from dyes or bleaches, but because of the tree to which the lac bug has attached itself—the sap affects the color of the bug secretions thus altering the color of the refined shellac. 
Shellac may be applied to wood, over varnish, paint, glass, ceramics, even plastic with remarkable adherence, but Shellac cannot be used under synthetic sealers such as polyurethane.

-Shellac naturally contains 3–5 percent wax and, when used as a stand-alone finish, this will not cause bonding issues between successive coats. 
But, when using it as a primer or sealer under another finish, choose dewaxed shellac to eliminate compatibility issues.
-Coveted for Shellac's binding abilities and glossy appearance, the material is present in a range of personal care products and cosmetics. 
Shellac is used to add shine to nail polish and hair spray, bind mascara, emulsify moisturizers, and protect fragrances from oxidation.

-A shellac base coat is a layer of resin paint that is applied to a surface to protect the surface from future painting or to create a flat and clean surface to which a finishing coat will stick. 
Shellac is used as a base coat because Shellac's color is resilient when placed on wood finishes, and Shellac can be layered several times to also be used as a finishing coat. 
Colors and tints can be added to shellac to create a wide range of colors, with white shellac being an effective way to cover up surfaces that have extensive discoloration. 
The widespread use of shellac as a base coat has declined with the introduction of synthetic coatings.

-The substance from which shellac is made is a resin deposited on trees by a type of insect. 
Shellac can take on one of a range of earth-tone colors, from very pale yellows to deep browns. 
-One type of shellac base coat is called a wash coat. 
This is similar to a normal base coat in that the shellac is simply applied to a surface, except the shellac is first thinned down with denatured alcohol. 
The result is a very thin base coat that can help to penetrate and seal a surface that will then receive a finishing coat.

-The wax content of a shellac base coat means only shellac or oil-based paints can be applied over top. 
Water-based paints and polyurethane paints will have trouble sticking to the waxy surface and could bead up or peel off after a time. 
A solution to this problem is to use a de-waxed shellac base coat. 
Without the presence of wax, any paint can be used over top of the shellac.

-Applying a shellac base coat can sometimes be difficult. 
Using a brush with shellac can be problematic because, as it dries, brush strokes are left behind. 
A method that can work without leaving lines is to use a cloth or sponge to quickly get the shellac smoothed on a surface. Other methods, such as using a spray can or spray gun, also can work but are not recommended for small surfaces because of the amount of overspray that can occur.

-Non-toxic:
Shellac is the safest finish you can use. 
It is a naturally occurring, organic material that’s approved by the FDA to coat apples, candy and pharmaceuticals. 
When mixed with pure grain alcohol, shellac is completely free of toxic chemicals.
-Repairable:
A damaged or worn shellac finish is easy to restore or repair.

-Rubs out well:
Shellac is harder than most finishes, including polyurethane. 
The hardness gives it excellent rubbing qualities.
-Excellent moisture barrier:
If you want to keep wood movement to a minimum, shellac can’t be beat.

-Fast drying:
That means fewer troubles with dust settling into a wet film. 
You can usually recoat in under an hour for a fast build.
-Universal sealant:
Dewaxed shellac can be used as a seal coat under almost any finish.
-Less Sanding:
Shellac does not require sanding between coats in order for one coat to adhere to another.

THE MANUFACTURING PROCESS of SHELLAC::
THE ROLE of THE LAC BUG:
1) 
Shellac is produced by a tiny red insect. 
Swarms of the insects feed on certain Shellactrees, primarily in India and Thailand, known informally as lac trees. 
The lac bugs' life cycle is only six months, in which time they eat, propagate, and secrete the resin they've taken in from the tree to produce shellac.

In certain seasons of the year, these insects swarm in huge numbers on the trees, settle on branches, and project protrusions into the tree to penetrate the bark. 
They suck up the sap and absorb it until they feed themselves to death (called the feast of death amongst the indigenous peoples). 
At this same time, propagation continues, with each female lac bug laying about 1,000 eggs before dying.
The sap is chemically altered in the lac bug's body and is then exuded onto the tree branch. 

On contact with the air, the excretion forms a hard shell-like covering over the entire swarm. 
This covering forms a crust over the twig and insects. 
As the female lac bug is exuding the ingested sap she is preparing to die and is providing a fluid in which her eggs will mature under protection. 
The males' role is to fertilize the female, and it is after fertilization that the females' lac output is vastly increased. The adult males and females become inactive, and the young start to break through the crust and swarm out.

REFINING THE CRUSTY RESIN:
2)
Workers cut millions of encrusted branches, called sticklac, for transportation to refineries of some sort (either handrefined or mechanically refined). 
Some workers use mallets and break off the crusty coating much as ice is broken from branches in the winter (it is referred to as grainlac).

3) 
At refining centers, sticklac is scraped to remove the secretions from the twigs. 
Sticklac and grainlac is ground with rotating millstones. 
The resulting ground material is quite impure, containing resin, insect remains, twigs, leaves, etc. 
The mixture is forced through a screen, removing the largest of the impurities.

4)
The sifted resin mixture is put into large jars and stomped by a worker to crush granules and force the red dye from the lac seeds and the insect remains will be freed from the resin. 
Dye water, scum, and other impurities are then washed away in several rinsings. 
The mixture is spread out on a concrete floor to dry and called seedlac because it resembles seed. 
Seedlac is the raw material from which both orange shellac and bleached or clear shellac are produced.
Shellac may be made from seedlac by hand or by modern mechanical equipment. 
Nearly all American-used shellac is refined with the help of machinery, using a heat-or solvent-based process.

HEAT PROCESS:
5) 
Seedlac is melted onto steam-heated grids. 
The molten lac is forced by hydraulic pressure through a sieve or screen, either of cloth or fine mesh. 
The filtered shellac is collected and transferred to a steam-heated kettle, which then drops the molten liquid onto rollers. The liquid is squeezed through the rollers and forced into large, thin sheets of shellac. 
When dry, this shellac sheet is broken into flakes and transported to another area in which the flakes are combined with denatured alcohol to produce the consumer's shellac.

SOLVENT PROCESS:
6) 
In this process, the seedlac and solvent, usually ethyl alcohol, are mixed in a dissolving tank, refluxed for about an hour and then filtered to remove impurities. 
The filtered resin is sent through evaporators that remove the alcohol solvent, rendering it a viscous liquid. 
This liquid is then dropped onto rollers, which force it into sheets. The sheets are then are dried and flaked apart.

BLEACHED SHELLAC:
Despite the removal of much of the red dye from the lac seeds in the refining process, shellac remains an orangish solution after processing is complete. 
Some consumers prefer a clear shellac finish, so manufacturers have developed a way to bleach the color from the shellac.

7)
Bleaching begins with dissolving seedlac, which is alkali-soluble, in an aqueous solution of sodium carbonate. 
The solution is then passed through a fine screen to remove insoluble lac, dirt, twigs, etc. 
The resin is then bleached with a dilute solution of sodium hypochlorite to the desired color. 
The shellac is then precipitated from the solution by the addition of dilute sulfuric acid, filtered, and washed with water. Shellac is dried in vacuum driers and ground into a white powder ready for shipment to a plant that will add liquid to the flakes.

8)
Large shellac manufacturers are shipped the dry shellac flakes. 
They then remoisturize the flakes by adding denatured ethyl alcohol. 
Shellac is offered to the consumer in flake form or suspended in denatured alcohol. 
Shellac is the latter than is most popular with the consumer. 

Manufacturers of shellac refer to the concentration of shellac flakes to denatured alcohol in terms of pounds of cuts—the number of pounds of shellac flakes dissolved into a single gallon of denatured alcohol. 
Thus, a one pound cut of shellac contains one pound of shellac flakes dissolved in a gallon of alcohol—very dilute shellac. The manufacturers' standard cut offered to the consumer pre-mixed is termed a three pound cut. 
Some consumers then dilute it further with denatured alcohol if they so desire.

The most popular shade of shellac sold premixed is the orange shellac although clear or white shellac is also offered pre-mixed to the consumer. 
Manufacturers always stamp the date of mixing of the shellac into the can. 
Each manufacturer has a recommended shelf life for the product and the consumer should heed that the product is not used after the period suggested by the manufacturer. 
If used after the time span recommended, the shellac may never dry completely.

OCCURRENCE and PREPARATION of SHELLAC:
Shellac is the refined form of lac, the secretion of the lac insect parasitic on certain trees in India, Burma, Thailand and to a minor extent in other Asian countries.
The larvae of the lac insect, Laccifer lacca (Kerr), swarm around the branches and twigs of the host trees for 2–3 days before inserting their probosces into the phloem tissues to reach the sap juices. 
There may be as many as 100–150 larvae on each inch of twig. 

This is followed by secretion of the lac surrounding the cells. 
Whereas the male insects subsequently move out of their cells the female insects become entombed for life. 
After about eight weeks of life the male insects fertilise the females and die within a few days. 
The fertilised females subsequently exude large quantities of lac and shed eyes and limbs. 
The female gives birth to 200–500 further insects and finally dies.

In commercial practice the crop is taken from the tree shortly before emergence of the new brood. 
Some of these twigs are then tied to new trees to provide future sources of lac but the rest, sticklac, is subjected to further processing. 
The average yield per tree is about 20 lb per annum, usually one crop being allowed per tree per year.
Subsequent treatment of the sticklac carried out by hand or by mechanical methods first involves removal of woody matter and washing to remove the associated lac dye to produce seedlac, containing 3–8% of impurities. 

This may be further refined by various methods to produce the shellac flakes of commerce.
The hand process for producing shellac has been used since ancient times and is carried on largely as a cottage industry. 
The lac encrustation is first separated from woody matter by pounding with a smooth stone, the latter being removed by a winnowing process. 
The lac dye is then removed by placing the lac in a pot together with a quantity of water. 
A villager, known as a ghasander, then stands in the pot and with bare feet treads out the dye from the resin. 

At one time lac dye was of commercial value but is today a worthless by-product. 
The product, seedlac, is then dried in the sun.
The next stage may best be described as a primitive hot-filtration process. 
Two members of the village sit across the front of a simple fire resembling a Dutch oven, holding between them a bag about 30 feet long and about two inches in diameter. 

The lac inside the bag melts and, through one of the operators twisting the end of the bag, the lac is squeezed out. 
The lac is then removed from the outside of the bag and collected into a molten lump which is then stretched out by another operator using both hands and feet until a brittle sheet is produced. 
This is then broken up to produce the shellac of commerce.
In the factory processes the sticklac is first passed through crushing rollers and sieved. 

The lac passes through the sieve but retains the bulk of the woody matter. 
The sieved lac is then washed by a stream of water and dried by a current of hot air. 
A second mechanical cleaning process removes small sticks which have not been removed in the earlier roller process. 
The product, seedlac, now contains 3–8% of impurities.
The seedlac may then be converted to shellac by either a heat process or by solvent processes. 

In the heat process the resin is heated to a melt which is then forced through a filter cloth which retains woody and insoluble matter. 
In the solvent process the lac is dissolved in a solvent, usually ethyl alcohol. 
The solution is filtered through a fine cloth and the solvent recovered by distillation.
Variation in the details of the solvent processes will produce different grades of shellac. 

For example, when cold alcohol is used, lac wax which is associated with the resin remains insoluble and a shellac is obtained free from wax. 
Thermally processed shellacs were greatly favoured for gramophone records as they were free from residual solvent and also contained a small quantity of lac wax which proved a useful plasticiser.

PRODUCTION of SHELLAC:
Shellac is scraped from the bark of the trees where the female lac bug, Kerria lacca (order Hemiptera, family Kerriidae, also known as Laccifer lacca), secretes Shellac to form a tunnel-like tube as Shellac traverses the branches of the tree. 
Though these tunnels are sometimes referred to as "cocoons", they are not cocoons in the entomological sense. 
This insect is in the same superfamily as the insect from which cochineal is obtained. 
The insects suck the sap of the tree and excrete "sticklac" almost constantly. 

The least-coloured shellac is produced when the insects feed on the kusum tree.
The number of lac bugs required to produce 1 kilogram (2.2 lb) of shellac has variously been estimated as 50,000, 200,000, or 300,000. 
The root word lakh is a unit in Indian numbering system for 100,000 and presumably refers to the huge numbers of insects that swarm on host trees, up to 150 per square inch (23/cm2).

The raw shellac, which contains bark shavings and lac bugs removed during scraping, is placed in canvas tubes (much like long socks) and heated over a fire. 
This causes the shellac to liquefy, and it seeps out of the canvas, leaving the bark and bugs behind. 
The thick, sticky shellac is then dried into a flat sheet and broken into flakes, or dried into "buttons" (pucks/cakes), then bagged and sold. 

The end-user then crushes it into a fine powder and mixes it with ethyl alcohol before use, to dissolve the flakes and make liquid shellac.
Liquid shellac has a limited shelf life (about 1 year), so is sold in dry form for dissolution before use. 
Liquid shellac sold in hardware stores is often marked with the production (mixing) date, so the consumer can know whether the shellac inside is still good. 

Some manufacturers (e.g., Zinsser) have ceased labeling shellac with the production date, but the production date may be discernible from the production lot code. 
Alternatively, old shellac may be tested to see if it is still usable: a few drops on glass should dry to a hard surface in roughly 15 minutes. 
Shellac that remains tacky for a long time is no longer usable. 
Storage life depends on peak temperature, so refrigeration extends shelf life.

The thickness (concentration) of shellac is measured by the unit "pound cut", referring to the amount (in pounds) of shellac flakes dissolved in a gallon of denatured alcohol. 
For example: a 1-lb. cut of shellac is the strength obtained by dissolving one pound of shellac flakes in a gallon of alcohol (equivalent to 120 grams per litre). 
Most pre-mixed commercial preparations come at a 3-lb. cut. 

Multiple thin layers of shellac produce a significantly better end result than a few thick layers. 
Thick layers of shellac do not adhere to the substrate or to each other well, and thus can peel off with relative ease; in addition, thick shellac will obscure fine details in carved designs in wood and other substrates.
Shellac naturally dries to a high-gloss sheen. 
For applications where a flatter (less shiny) sheen is desired, products containing amorphous silica, such as "Shellac Flat", may be added to the dissolved shellac.

Shellac naturally contains a small amount of wax (3%–5% by volume), which comes from the lac bug. 
In some preparations, this wax is removed (the resulting product being called "dewaxed shellac"). 
This is done for applications where the shellac will be coated with something else (such as paint or varnish), so the topcoat will adhere. 
Waxy (non-dewaxed) shellac appears milky in liquid form, but dries clear.

COLOURS and AVAILABILITY of SHELLAC:
Shellac comes in many warm colours, ranging from a very light blonde ("platina") to a very dark brown ("garnet"), with many varieties of brown, yellow, orange and red in between. 
The colour is influenced by the sap of the tree the lac bug is living on and by the time of harvest. 
Historically, the most commonly sold shellac is called "orange shellac", and was used extensively as a combination stain and protectant for wood panelling and cabinetry in the 20th century.

Shellac was once very common anywhere paints or varnishes were sold (such as hardware stores). 
However, cheaper and more abrasion- and chemical-resistant finishes, such as polyurethane, have almost completely replaced Shellac in decorative residential wood finishing such as hardwood floors, wooden wainscoting plank panelling, and kitchen cabinets. 
These alternative products, however, must be applied over a stain if the user wants the wood to be coloured; clear or blonde shellac may be applied over a stain without affecting the colour of the finished piece, as a protective topcoat. 
"Wax over shellac" (an application of buffed-on paste wax over several coats of shellac) is often regarded as a beautiful, if fragile, finish for hardwood floors. 

Luthiers still use shellac to French polish fine acoustic stringed instruments, but Shellac has been replaced by synthetic plastic lacquers and varnishes in many workshops, especially high-volume production environments.
Shellac dissolved in alcohol, typically more dilute than French-Polish, is now commonly sold as "sanding sealer" by several companies. 
Shellac is used to seal wooden surfaces, often as preparation for a final more durable finish; Shellac reduces the amount of final coating required by reducing Shellac's absorption into the wood.

A few coats of shellac add color and depth—even to ho-hum woods like pine—that you can’t get with other finishes. 
Going Green:
Shellac doesn’t exactly grow on trees, but lac, an insect secretion, is havested off tree bark. 
In addition to being a renewable resource, shellac is one of the least toxic wood finishes. 
Shellac is still used as a glazing agent on pills and candies.

Many shades of shellac:
Shellac is sold in a variety of different colors. 
When starting out, you may want to stick with darker shellacs on darker woods (use garnet to spice up kiln-dried walnut) and lighter shellacs on light woods (blonde flakes add a hint of color to maple), but as you’ll soon discover, shellac can serve as an effective dye toner. 
Unlike pigment stains, shellac adds rich, warm tones without obscuring the grain.

The best way to explore shellac’s possibilities is to make a few sample boards like those shown above. 
To fine-tune your hues, you can apply one shade over another, combine different shellacs to make a custom blend, or add an alcohol-soluble dye. 
As you’ll see, shellac’s color will darken with each additional coat, but what you see is what you’ll get—for good. Unlike some varnishes or lacquers, shellac doesn’t yellow or become cloudy with age.

There are five commonly available grades of shellac from least refined to most refined: 
-Seedlac
-Buttonlac
-Garnet
-Orange
-Super blonde. 

Seed-Lac is simply collected from the trees, washed and dried. 
Seed-Lac still contain leaves, sticks and bug parts. 
Buttonlac has been filtered a bit. 
Buttonlac has a rich, dark brown color. 

Garnet is a little lighter colored and has more red than Buttonlac. 
Orange shellac is probably the most familiar grade to consumers. 
Super Blonde shellac is the most highly refined. 
Super Blonde shellac has most of the color and all the wax removed. 
All dry shellacs should be strained through a fine filter after mixing.

TYPES of SHELLAC:
Not only is there no benefit to using shellac as a sealer in most situations, there are good reasons not to use it. 
Shellac is a difficult finish (or sealer) to use.
The first reason is the confused naming. 
In liquid form there are clear (actually pale yellow) and amber shellacs. 
Until about 20 years ago, when Zinsser changed the names for marketing purposes, these were labeled “white” and “orange.” 

In flake form, which you dissolve yourself in denatured alcohol, there are many more varieties: blonde, superblonde, lemon-yellow, orange, garnet, button, ruby, extra dark and more. 
These names all refer to the color, ranging from pale yellow to very dark orange.
A second issue is the way solids content is measured. 
Shellac’s not the standard percentage method used for all other finishes. 
Shellac’s “pound cut” — the number of pounds of shellac resin dissolved in one gallon of alcohol.

A fourth issue is blushing. 
You can control blushing with products that thin with lacquer thinner. 
Just add some retarder. 
A fifth issue is ridging. 
Unless you thin shellac a good deal, Shellac has a tendency to ridge at the edge of brush strokes and orange peel when sprayed.

HISTORY of SHELLAC:
The earliest written evidence of shellac goes back 3,000 years, but shellac is known to have been used earlier. 
According to the ancient Indian epic poem, the Mahabharata, an entire palace was built out of dried shellac.
Shellac was in rare use as a dyestuff for as long as there was a trade with the East Indies. 
Merrifield cites 1220 for the introduction of shellac as an artist's pigment in Spain. 
Lapis lazuli, an ultramarine pigment from Afghanistan, was already being imported long before this.

The use of overall paint or varnish decoration on large pieces of furniture was first popularised in Venice (then later throughout Italy). 
There are a number of 13th-century references to painted or varnished cassone, often dowry cassone that were made deliberately impressive as part of dynastic marriages. 
The definition of varnish is not always clear, but it seems to have been a spirit varnish based on gum benjamin or mastic, both traded around the Mediterranean. 

At some time, shellac began to be used as well. 
An article from the Journal of the American Institute of Conservation describes using infrared spectroscopy to identify shellac coating on a 16th-century cassone. 
This is also the period in history where "varnisher" was identified as a distinct trade, separate from both carpenter and artist.

Another use for shellac is sealing wax. 
Woods's The Nature and Treatment of Wax and Shellac Seals discusses the various formulations, and the period when shellac started to be added to the previous beeswax recipes.
The "period of widespread introduction" would seem to be around 1550 to 1650, when the substance moved from being a rarity on highly decorated pieces to being described in the standard texts of the day.

Lac has been cultivated for three centuries. 
For most of that time, the lac bug secretions were valued for the purple-red dye derived from being soaked in water. 
This dye was used to color silk, leather, and cosmetics and was cultivated primarily for this purpose until the 1870s. 
Then aniline or chemical dyes began to supplant these and other natural dyes.

As early as the sixteenth century, references were made to the usefulness of the lac bug secretions as a decorative lacquer for furniture and fine musical instruments. 
Natives of the Far East had laboriously cultivated and processed the shellac by hand, scraping the branches encrusted with the lac bug secretions, forcing the secretions into muslin, and holding long muslin bags of the secretions over the fire to liquefy and purify it. 
They pulled it by hand into huge sheets and then broke the sheets into flakes for re-moisturizing later.

Hand processes were partially replaced by the mid-nineteenth century. 
Just as the lacderived dye was about to fade in popularity, industrial plants began processing the lac secretions for use as a wood sealer and finish. 
In 1849, William Zinsser founded Wm. Zinsser & Company in New York. Zinsser's shellacs were soluble in ethyl alcohol and were the first quick-drying, tough, colorless

Shellac finishes available in the United States. 
Shellac was particularly popular late in the nineteenth century and in the early twentieth century when houses were being quickly built in early subdivisions at break-neck speed—shellac was an ideal wood finisher because Shellac was so fast to dry and several coats could be applied in a single day. 
A shellac known as buttonlac, a very dark shellac, imparted a very deep walnut color to inexpensive woodwork that people then found very desirable.

DIFFERENCES BETWEEN SHELLAC AND LACQUER:
The principle differences between nitrocellulose lacquer and shellac are ease of application and their ability to block off problems in the wood. 
Both finishes are evaporative finishes, meaning that they dry entirely by solvent evaporation; there is no crosslinking as there is with varnish and catalyzed finishes.

As a result, both lacquer and shellac are more vulnerable to being damaged by coarse or sharp objects, heat, solvents, acids and alkalis. 
Shellac is more vulnerable than lacquer to being damaged by alcohol spills, of course, but keep in mind that beer, wine and mixed drinks are usually very watered down, so the vulnerability is much less than a straight alcohol spill.

Lacquer is much more user friendly than shellac because of the difference between thinners. 
Lacquer thinner is made up of a number of different solvents (usually about six, except in areas with strict VOC rules) that evaporate at different rates. 
This allows finishers to control the drying rate of the finish to avoid blushing, and runs and sags. 
With the right lacquer thinner, lacquer can even be applied successfully in cold temperatures. 
We have almost no control of the drying rate of shellac with just alcohol as the solvent.

But shellac has the advantage of being able to block off problems in the wood, such as silicone, which causes fish eye, various other oils, resin in oily woods, wax, etc. 
Shellac, therefore, can be useful as a sealer coat if you have one of these problems. 
For the most part, shellac is a great tool for refinishers who often encounter silicone problems, but of almost no advantage for finishing new wood.

DEWAXED VS WAXED of SHELLAC:
Dewaxed shellac makes an excellent sealer over stains and under lacquer (helps keep fisheye-causing contaminates out of topcoats, too) and is useful for finish repairs and touchups. 
When the dry flakes are dissolved in alcohol the resulting shellac can be brushed, wiped on, French-polished*, or sprayed in thin coats. 
Shellac has good clarity and compatibility with most finishes, is easy to rub out, and easy to repair with additional shellac.

Waxy shellac is excellent when the finish will be only shellac (as in a French polish finish). 
Amber in color, it adds a bit more moisture resistance and flexibility to the final finish. 
Shellac contains none of the shelf-life additives found in ready-mixed shellacs that can be unsuitable for French polishing. 
Apply by hand, using a padded cloth.
Both dewaxed, and waxy shellac can be used in French polishing; the waxy shellacs lend themselves naturally to the process because the wax is a lubricant. 
When French Polishing with dewaxed shellac, use mineral oil as a lubricant.

Should you buy waxed or de-waxed shellac? 
Wax occurs naturally in shellac. 
If shellac is going to be the only finish, then shelalc with wax works fine. 
The wax decreases drag when padding or brushing on shellac. 
If shellac is used as a sealer or undercoat for other finishes, choose the dewaxed version to avoid adhesion problems, especially with polyurethane. 

Dewaxed shellac also has greater clarity and is more heat and water resistant. 
You can dewax your own shellac by letting the wax settle out and pouring off the clear dewaxed portion.
The next decision a shellac buyer makes is color. 
A good rule of thumb is to use the darker colors on darker woods and light colors on light.

WHAT IS THE DIFFERENCE BETWEEN POLYURETHANE, LACQUER & SHELLAC FINISHES?
Shellac, Lacquer and Polyurethane, are the variety of finishes used on the furniture and you might have come across them while buying furniture for your home. 
Although, all these are doing similar jobs of making your furniture look beautiful with that extra shine yet there are some differences between these finishes that you must know before selecting them for your furniture.  

Choosing the right finish for your wood project is the key for getting the results you want, but knowing where to start from can be a bit confusing—until you understand a few basics.
Let’s first talk about what they have in common:

-All these finishes protect the wood.
-All are applied as a top coat.
-All create a smooth, clear finish on the wooden surface.
Despite having so many similarities, these products are recommended not to be used interchangeably. 

Following is a basic description of Shellac, Lacquer and Polyurethane Finishes and differences between them, take a look.
Shellac: This finish is virtually a natural product that creates a lustrous, mid-gloss sheen with a golden tint.
Lacquer: Lacquer is a clear nitrocellulose dissolved in a solvent that creates a crystal-clear, hard wearing finish and can be applied by sprayer for an ultra-smooth surface. 
Lacquer comes in satin, semi-gloss and gloss. 
Lacquer’s also available in an aerosol option.

Polyurethane: This durable product is available in several finishes ranging from matte to gloss. 
Oil-based is the hardiest and has a slight amber hue, while water-based has less odor and a crystal clear finish. 
Also, polyurethane (poly) comes in two formulations (water and oil-based) that can be applied accordingly.
Dry to Touch: While oil-based polyurethane requires 4 hours to dry to touch, rest of the finishes are much faster:

Lacquer (30 min.)
Shellac (1 hr.)

Water-based poly (2 hours)
Easy to Apply: 
If you want to ensure no brush marks and an even finish, oil-based poly is your best bet— it self-levels, correcting inconsistencies in your application. 
Lacquer is even more forgiving, letting you skip sanding and hole-filling altogether.

Easy to Clean:   
All finishes are easy to clean, however, water-based poly is best out of these as it can be washed off with just soap and water.

Best for a Golden Glow:  
Oil-based poly and shellac bring out the warmth and beauty of natural wood.

Best for Ultra-Clear Finish: 
Lacquer is the best choice for leaving the desired color exactly as is—because of its high clarity. 
Water-based poly is the second-best option.

Most Durable: Poly stands up best to scuffs, scratches and wear.

THINNING RATIOS
The term "cut" is used when referring to the amount of alcohol added to dry shellac flakes to dissolve them (one pound of shellac flakes dissolved in one gallon of alcohol gives a well-thinned one-pound cut). 
Store-bought shellac is usually sold in a heavier three- to four-pound cut, and then thinned accordingly. 

ADVANTAGES OF SHELLAC
Shellac is an excellent sealer because it sticks to almost anything. 
Shellac has a golden color and a quality that makes wood look beautiful. 
Shellac can be brushed, sprayed, or French polished.
Shellac blocks out, or seals in, trace amounts of oil, wax, and silicone.
Shellac is easily repaired.

PHYSICAL and CHEMICAL PROPERTIES of SHELLAC:
-DryPowder; OtherSolid; PelletsLargeCrystals; WetSolid
-Bleached shellac — off-white, amorphous, granular resin; Wax-free bleached shellac — light yellow, amorphous, granular resin
Molecular Weight: 586.7
Solubility: Insoluble in water; freely (though very slowly) soluble in alcohol; slightly soluble in acetone.
Acid Value: Between 60 and 89
Appearance Form: solid
Odour: No data available
Odour Threshold: No data available

pH: No data available
Melting point/freezing point: No data available
Initial boiling point and boiling range: No data available
Flash point: No data available
Evaporation rate: No data available
Flammability (solid, gas): No data available
Upper/lower flammability or explosive limits: No data available
Vapour pressure: No data available
Vapour density: No data available

Relative density: No data available
Water solubility: No data available
Partition coefficient: n-octanol/water: No data available
Auto-ignition temperature: No data available
Decomposition temperature: No data available
Viscosity: No data available
Explosive properties: No data available
Oxidizing properties: No data available

FIRST AID MEASURES of SHELLAC:
-Description of first aid measures:
*If inhaled:
If breathed in, move person into fresh air. 
If not breathing, give artificial respiration.
*In case of skin contact:
Wash off with soap and plenty of water.
*In case of eye contact:
Flush eyes with water as a precaution.
*If swallowed:
Never give anything by mouth to an unconscious person. 
Rinse mouth with water.

ACCIDENTAL RELEASE MEASURES of SHELLAC:
-Personal precautions, protective equipment and emergency procedures:
-Environmental precautions:
Do not let product enter drains.
-Methods and materials for containment and cleaning up:
Sweep up and shovel. 
Keep in suitable, closed containers for disposal.

FIRE FIGHTING MEASURES of SHELLAC:
-Extinguishing media:
Suitable extinguishing media:
Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide.
-Advice for firefighters:
Wear self-contained breathing apparatus for firefighting if necessary.
-Further information: No data available

EXPOSURE CONTROLS/PERSONAL PROTECTION of SHELLAC:
-Control parameters:
Components with workplace control parameters:
-Exposure controls:
Appropriate engineering controls:
General industrial hygiene practice.
-Personal protective equipment:

*Eye/face protection:
Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU).

*Skin protection:
Handle with gloves. 
Gloves must be inspected prior to use. 
Use proper glove removal technique (without touching glove's outer surface) to avoid skin contact with this product. 
Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices. 
Wash and dry hands.
The selected protective gloves have to satisfy the specifications of Regulation (EU) 2016/425 and the standard EN 374 derived from it.
Full contact:
Material: Nitrile rubber
Minimum layer thickness: 0,11 mm
Break through time: 480 min
Splash contact
Material: Nitrile rubber
Minimum layer thickness: 0,11 mm
Break through time: 480 min

*Respiratory protection:
Respiratory protection is not required. 
Where protection from nuisance levels of dusts are desired, use type N95 (US) or type P1 (EN 143) dust masks. 
Use respirators and components tested and approved under appropriate government standards such as NIOSH (US) or CEN (EU).

*Control of environmental exposure:
Do not let product enter drains.

HANDLING AND STORAGE of SHELLAC:
-Precautions for safe handling:
-Conditions for safe storage, including any incompatibilities:
Store in cool place. 
Keep container tightly closed in a dry and well-ventilated place.

Storage:
Once shellac flakes are mixed with alcohol, the mixture has a shelf life of no more than a year and a half. 
Keeping Shellac cool will increase mixed shellac's shelf life. 
If you buy off-the-shelf pre-mixed shellac, always test Shellac for drying by putting several drops on a nonporous surface. 
Leave a thick drop or two, spread the rest into a thin layer, and let Shellac dry all night. 
By the next day, the thin layer should be dry and sandable. 
The thicker drop shouldn't easily take an imprint from your thumbnail. 
If Shellac does, Shellac may be usable but questionable—give Shellac another day or two of test-drying before using it.

STABILITY and REACTIVITY of SHELLAC:
-Reactivity: No data available
-Chemical stability: Stable under recommended storage conditions.
-Possibility of hazardous reactions: No data available
-Conditions to avoid: No data available

SYNONYMS:
(2R,6S,7R,10S)-10-hydroxy-6-(hydroxymethyl)-6-methyltricyclo[5.3.1.0]undec-8-ene-2,8-dicarboxylic acid;9,10,15-trihydroxypentadecanoic acid
Shellac ammonium salt