SHELLAC – A TRADITIONAL FINISH STILL YIELDS SUPERB RESULTS

by Jeff Jewitt

To the average person, shellac probably invokes many negative perceptions. Poor waterand heat resistance, difficult to apply, poor drying and low durability are all criticismsthat I hear when I mention shellac to my clients or other woodworkers. While some of thesecriticisms are valid, many are not grounded in fact and are easy to disprove. Othernegative aspects are overcome by using proper tools, techniques, and most important --proper product.

To experienced finishers and restorers of fine furniture the world over, shellacremains the finish of choice. One of the most elegant finishes for furniture, FrenchPolish, is done with shellac. Conservators and restorers of antiques use shellac forre-finishing antiques. And most importantly, its low toxicity makes it a perfect choicefor items that come into contact with food or children's toys. There are countless otheradvantages to using shellac that are listed in at the end of the article. But as withevery finish option available, there are disadvantages and these are listed also.

HISTORY

Most people have no idea of what shellac is or where it comes from. Shellac is anatural, organic resin that comes from an insect, Laccifera lacca, that is about the sizeof an apple seed. This bug alights on certain trees indigenous to India and Thailand andduring its reproductive cycle feeds on the sap that it sucks from the twigs of thesetrees. The bug secretes an amber colored resinous substance that is called"lac", a word that comes from the Sanskrit "lakh" which meansone-hundred thousand. The resin forms a cocoon around the insect which serves to incubatethe eggs she lays. This cocoon is the raw material for shellac and is called"sticklac", because it contains resin, parts of the twig and bug remains. Thesticklac is washed and then refined either chemically or by hand, to produce the rawmaterial available for sale to commerce.

The original cultivation of shellac was not for the resin, but rather, for the dye thatgives the resin its characteristic color. The use of lac dye can be traced back to 250 ADwhen it was mentioned by Claudius Aelianus, a Roman writer in a volume on natural history.The lac dye was removed by the initial washing of the shellac resin in large kettles,which is also the first step in preparing the resin. This dye remained a valuablecommodity until the mid-1800's, when Perkins, an English chemist, synthesized the firstchemical 'aniline' dyes which killed the natural dye industry. Fortunately the use of theresin had been firmly established, so the loss of the use of the dye had little impact onshellac trade. The first use of shellac as a protective coating appears as early as 1590in a work by an English writer who was sent to India to observe the country and itspeople. Commenting on a procedure for applying lac to wood still on the lathe he writes"they take a peece of Lac of what colour they will, and as they turne it when itcommeth to his fashion they spread the Lac upon the whole peece of woode which presently,with the heat of the turning (melteth the waxe) so that it entreth into the crestes andcleaveth unto it, about the thicknesse of a man's naile: then they burnish it (over) witha broad straw or dry Rushes so (cunningly) that all the woode is covered withall, and itshineth like glasse, most pleasant to behold, and continueth as long as the woode beingwell looked unto: in this sort they cover all kinde of household stuffe in India".* (It's interesting that many woodturners still finish this same way today.) * From"Shellac; its production, manufacture, chemistry analysis, commerce and uses."London, Sir I. Pitman & Sons, ltd.,

1935 pg. 3.

The use of shellac as a furniture finish never caught on in the West until the early1800's and it eventually replaced wax and oil finishes. It remained the most widely usedprotective finish for wood until the 1920's and 30's when it was replaced bynitrocellulose lacquer.

SHELLACS OTHER USES

The most fascinating uses of shellac have nothing to do with finishes. Because of itsspecific characteristics, it has a wide variety of uses, most of which continue to thisday. According to the Zinsser Company, which is the largest supplier of shellac in thiscountry, the top four uses for the dry shellac flakes are pharmaceutical, confectionery,hats, and food coatings, in order from highest to lowest. Protective coatings for woodranks about number eight.

Pharmaceutical

- shellac is used to coat enteric pills so that they do not dissolvein the stomach, but in the lower intestine, which alleviates upset stomachs. Its also usedas a coating on pills to "time release" medication.

Confectionery

- shellac is used to provide protective candy coatings or glazes oncandies like Reese's Pieces, because of its unique ability to provide a high gloss inrelatively thin coatings (like a French Polish). It was used at one time on M&M's. Itis approved by the FDA as a food safe coating when dissolved in pure ethanol (notdenatured).

Hats

- shellac is used to stiffen felt used to make hats. It allows the makers toshape the felt into brims, bowl shapes, etc.

Food Coatings

- because of its FDA approval, shellac is used to coat apples andother fruits to make them shinier.

Electrical

– shellac mixed with marble dust is used by lamp manufacturers toglue the metal base to glass incandescent bulbs.

Other uses for shellac are in the manufacture of grinding wheels (it allows theabrasive particles to break off at the low heat generated by the grinding process, thusexposing new, fresh abrasive particles), leather finishing and painting (shellac pigmentedwith white titanium dioxide is widely used by painters as a stain sealer, wallboardprimer, and knot and sap sealer on wood).

Other former uses for shellac are electrical insulators, as a glue (it bonds glass andmetal surprisingly well), phonograph records (the old 78's were a mixture of shellac,fillers and lampblack), hair spray, no-rub floor polishes, and as a finish for bowlingalleys (the weight of the ball dropping on the shellac surface did crack the finish).

The demise of shellac's many uses was brought about by the emergence of more durablesynthetic resins such as Bakelite, cellulose nitrate, acrylics and urethanes. However, asmentioned above, it still finds a wide variety of applications in our society. It'sinteresting to note that many attempts in the early part of this century were made toduplicate the shellac resin. Despite the attempts by scientists to duplicate shellacsynthetically, a little Indian bug still makes it best.

THE MANY VARIETIES OF SHELLAC

Most woodworkers think of shellac as a liquid bought at a paint store. What many do notrealize is that shellac is traded and sold as dry flakes. Those who have used shellac froma paint store probably used a type known as #1 Orange, which is the most commonly tradedflake used as a wood finish. This is but one of the many grades of shellac available andit is dissolved in ethanol which is the most widely used solvent for shellac. The manyvarieties of shellac resin differ primarily in color as well as properties. The type oftree, climate conditions, the region where harvested, and the time of year harvested allplay a role in determining the different colors and grades of shellac.

The most expensive varieties of shellac are Kusmi and Golden Bysacki and these arechemically refined to extract adulterants such as rosin and wax into golden pale flakessold under a variety of names like Behlen's "Super-Blonde" or Kusmi Superior orBysacki Golden. When dissolved in ethanol, these flakes produce a very transparent goldfinish. The least expensive grade of shellac is traded as TN which stands for "trulynative" in this country. This type of shellac is processed from the raw sticklac byhand in India. Other grades of shellac which can be considered intermediates are #1 Lemonor Lemon-Orange all of which naturally contain wax. Some suppliers sell unrefined forms ofshellac known as Buttonlac or Seedlac. These grades need to be strained after dissolvingin ethanol to remove foreign matter. Seedlac is also further refined by bleaching and waxremoval to produce the white-shellac sometimes still sold in paint stores. The dry flakeform of this product is called "bone-dry" shellac flake and is widely used inapplications where the natural orange color of shellac would be undesirable (such ashats).

The shellac industry grades shellac by many variables, but the two most common are waxcontent and color. The most expensive shellacs, Kusmi and Bysacki, have virtually no waxcontent (less than 1%) and a high color number 70-80. The lower grades of shellac -- TN,orange lemon and buttonlac -- have a wax content from 3%-5 % and color numbers of 20 orlower.

Mail-order companies that sell dry shellac flakes classify it according to color (pale,dark, white, Super-blonde) and sometimes by grade (#1 Orange, Button-lac, Seedlac, etc.).Other characteristics to consider is whether it has been de-waxed. Dewaxed shellacs havemuch better transparency and moisture resistance. (The wax in the shellac reduces theclarity of the finish and also reduces the molecular weight of the shellac resin, makingit less resistant to water). On the downside, dewaxed shellacs have a much shorter shelflife after mixing with alcohol (less than 6 months).

DRY vs. DISSOLVED SHELLAC

Once the dry flakes are dissolved in ethanol, a chemical process known asesterification begins. What happens is that the alcohol starts to chemically modify thehard shellac resins and ultimately turns them into a sticky gum which doesn't dry. This isresponsible for one of the most often heard complaints about shellac -- that it won't dry.Large manufacturers such as Zinsser have started to label their cans with a shelf lifedate (three years), but for the best results and working properties, you achieve betterresults if you prepare your own shellac from dry flakes.

Dry shellac flakes store indefinitely under proper conditions, but contrary to what youmay hear, it won't store forever. Given enough time, especially under hot, wet conditions,dry shellac reacts with itself to form polymers that are insoluble in alcohol. Shellacsthat have been dewaxed are more prone to this. You can extend the usable life of dryshellac flakes by storing them after purchase in a cool, dry area -- a refrigerator isbest. A test for suspected old shellac is easy -- simply dissolve the flakes in alcohol.Most shellacs should be totally dissolved within three days. If you see a gelatinous massafter this time, the shellac is past its usable life and should be discarded (don’tconfuse natural wax with this). If you just purchased it, return it to the company youbought it from. Sometimes in summer months, shellac will cake together. This is known inthe industry as "blocking" and is not a sign of bad shellac. Break up theshellac with a hammer and dissolve it in alcohol as usual.

Dissolve dry shellac flakes in denatured ethanol, which is sold in most paint stores.It also dissolves in methanol, butyl and propyl alcohol. Methanol will evaporate thequickest, followed by ethanol, butyl and propyl alcohol. The last two alcohols, butyl andpropyl can be added to shellac dissolved in ethanol in small amounts to act as retarders,which make the shellac stay wet longer for better application (like brushing). Lacquerretarder can also be used. I do not recommend using methanol as a solvent because it isvery toxic. In some older finishing books, methanol is referred to as wood alcohol ormethylated spirits, but its use is discouraged.

Once dissolved in alcohol, shellac eventually esterifies as mentioned above. Although Ihave successfully used 12 month old shellac, shellacs older than 6 months should betested. Pour a small amount onto a piece of glass. If not dry to the touch within 5minutes, it should be discarded. For this reason, it's a good idea to make up only enoughshellac to use within a six-month period.

MAKING THE CUT

The ratio of dry shellac flakes dissolved in alcohol is known as the cut. It refers tothe amount in pounds of dry shellac flakes dissolved in 1 gallon of alcohol. A 3 lb. cutwould be 3 pounds of shellac dissolved in 1 gallon of alcohol. A 1 lb. cut would be 1pound of shellac dissolved in a gallon an so on. Since a gallon is a large amount for mosrfinishing tasks, you can factor down the ration to suit your needs. For example ¼ lbflakes dissolved in 1 pint of alcohol will yield a 2 lb. cut. It’s best to weigh theshellac flakes – small inexpensive food portion scales calibrated in ounces areavailable at houseware supply stores.

USING SHELLAC

There are many advantages to using shellac. Low toxicity, ease of application, and easeof repair are the best reasons to use shellac. Yet, like any finish, there are somedisadvantages which are mentioned below. However, some of the reasons people cite as thedisadvantages of shellac are based on misconceptions. Two of the most common ones can beeasily explained. The first is that it won't dry. This problem can be avoided by usingfreshly dissolved shellac flakes. The second complaint against shellac is poor moistureresistance. This can be overcome by using dewaxed shellac and fresh product. Using oldshellac solution will decrease its moisture resistance. You can easily prove this. Take aboard that has been finished with fresh shellac and after it has fully dried (about aweek), pour some water on the finish and let it sit overnight. When you come back the nextmorning you will still see the puddle of water, but the finish will be only slightlymarred. Shellacs ability to withstand water decreases with the age of the film, so don'ttry this on old finishes.

An interesting feature of shellac is that it resists water-vapor very well. In testsdone by the United States Forest Products Laboratory on the moisture-excludingeffectiveness of wood finishes (the ability of a finish to prevent moisture vapor fromentering the cellular structure of the wood – called MEE), shellac rated abovepolyurethane, alkyd and phenolic varnish and cellulose-nitrate based lacquers.

ADVANTAGES

1. Non-yellowing when compared to varnish and cellulose-nitrate based lacquers.

2. Quick-drying. Many shellacked items can used the same day or shortly thereafter.

3. Wide variety of colors available.

4. Superior adhesion -- no other type finish can surpass it.

5. Excellent hardness -- it can be sanded and rubbed out well.

6. Excellent as a sealer coat to raise the fibers of the wood for subsequent sanding.Also seals in finishing contaminants such as silicone, waxes, dirt and oils.

7. Ease of repair. Because shellac re-dissolves in alcohol, scratches and other minorsurface imperfections can be invisibly repaired by re-applying shellac to the damagedarea. The new shellac melts into the old shellac allowing for perfect repair work.

8. Ease of removal. Old and new shellac can be removed with denatured alcohol whicheliminates the need for harmful and toxic strippers.

9. Can be wiped on (padded), brushed or sprayed -- all with good results.

10. FDA approved -- safe for food utensils and children's toys.

11. No unpleasant or toxic fumes.

DISADVANTAGES

1. It re-dissolves in alcohol so perfumes and strong alcoholic beverages like whiskeywill mar the surface.

2. Forms white rings on contact with water. This is more of a problem with shellacsthat have wax and old shellac surfaces.

3. Tendency to show scratches. The resistance to scratches can be improved by a simplewaxing.

4. Has a shelf life after mixed in alcohol.

5. Not resistant to alkaline compounds. Alkaline chemicals such as lye and ammoniadiscolors and mars shellac because of its acidic composition. These chemicals arefrequently found in household cleaning products.

6. Sensitivity to heat -- shellac starts to soften at about 150 degrees F. Hot itemscan mar the surface.

Keep in mind that some of the disadvantages, like scratching and marring with alkalis,are easily repaired because of one of shellac's great advantages -- its ease of repair.

APPLYING SHELLAC

Shellac can be applied by practically any method -- brushing, padding, or spraying. Myfavorite method is padding, which many woodworkers may not have heard of. This techniquetakes advantage of shellac's rapid drying and allows the finisher to apply a finish in amuch shorter time than varnish, polyurethane or oil finishes. It works best on flatsurfaces, and in a nutshell, here's how it's done. Use a 2 lb. cut shellac and somepadding cloth, which is available from finishing suppliers as trace cloth or Frenchpolishing cloth. It should be as lint-free as possible. Do not use cotton T-shirt typecloth or cheesecloth.

Cut a piece of cloth roughly 10"-12" square. Fold it up into a pad so thatthere are no creases on the bottom. Pour about 1 ounce of alcohol on the cloth and workthe alcohol into the cloth. Then take a squirt bottle of shellac and dispenseapproximately one ounce of shellac into the pad. Starting at the top of the board, bringthe pad down on the surface like an airplane coming in for a landing, then lift it slowlyoff the board at the edge like taking off. Repeat this motion in stripes down the board.When you get to the bottom, the shellac that you put on the top will be dry enough to wipeagain. Keep doing this until the surface is tacky and the pad starts to stick. Betweenwipes, pad the edges. The trick to this is to apply light coats of shellac by keeping thepad moist, not dripping wet. (If you can squeeze shellac from the pad it's too wet). Whenfinished with padding, store the pad in a jar with a tight cap and re-use it. If this isthe first application on new wood, the shellac should penetrate quickly and be dry enoughto scuff-sand with 320 stearated sandpaper to remove the raised fibers in about an hour.Repeat the same process as above until the pad starts to stick. Let this application dryovernight and then scuff sand with 320 grit stearated sandpaper and then steel wool withmaroon synthetic steel wool or 000 regular steel-wool. Repeat the padding application onemore time and let it dry overnight. Then rub the finish out with 0000 steel wool, usingwax thinned with mineral spirits as a lubricant. After the wax dries to a haze, wipe theexcess wax off with a soft cotton cloth. This leaves a very mellow, hand-rubbed satinfinish.

This padding technique can also be used on sides, legs aprons and drawers, providedthey are relatively flat, but on complex surfaces I like to use a brush. A brush can alsobe used on the flat surfaces as described below.

BRUSHING SHELLAC

Brushing shellac is very different from brushing oil-based finishes such as varnish orpolyurethane. Part of the difficulty is that because shellac dries so fast you can't comeback later with a brush and even it out. It takes some practice but the following pointersshould help.

The best brushes for shellac are those that hold a lot of finish which allows you toflow it out on the board rather than brushing it. The brush that performs the best forflowing on finish is a fitch brush. Fitch brushes used to be pure skunk hair, but somehave soft badger hair on the outside to produce a smooth finish and a center of skunk hairto give the brush body. Most sold nowadays are very fine, soft china bristle dyed toresemble badger-hair. If you've never used an expensive brush before, you'll quicklyrealize that it's worth the price. My second choice for a shellac brush would be purewhite china bristle.

Before brushing, dip the brush all the way to the ferrule( the metal part near thehandle) into alcohol and then wring it out. This makes the brush easier to clean later.

I like to use a 1-1/2 lb. cut shellac solution for brushing. Take one part of theconcentrated solution prepared above and add 4 equal parts alcohol. This light cutminimizes brush marks which are hard to rub out later. Dip the brush about halfway intothe 1-1/2 lb. cut solution and bring the brush out and let the excess shellac run off,then drag it lightly across the top of the jar or can your using. Starting about 2"in from the edge, drag the brush lightly to the edge, then come back all the way to theother edge. Brush once and quickly come back to even out the finish if it's uneven, butdon't work it too much. Brushing shellac doesn't create air bubbles so these should not bea problem. Brush another coat next to the previous one, slightly overlapping it by about a1/4 inch. Work down the board until it's covered and then do the edges. After the shellacis dry, (1 hour for the first coat, overnight for subsequent coats), scuff sand and steelwool like the padding schedule above. Three coats should be sufficient for close-grainedwoods like cherry or maple, but you may want 4-5 coats on open-pored woods like mahogany.Rub the finish out with wax and steel-wool as above.

To clean brushes, you do not need to use expensive alcohol solvents. Household ammoniacleans shellac brushes because the alkaline ammonia dissolves the acidic shellac. Washingthe brush with soap (I use Dawn dish-washing detergent) and water afterwards keeps thebristles soft.

REPAIRS TO SHELLAC FINISHES

Over time, shellac finishes can show surface scratches and other minor mishaps likewater rings. These are very easy to repair with alcohol, the solvent for shellac. Surfacescratches can be repaired easily by flowing in a thin cut of shellac (1 lb.) into thescratch. Use a very fine artist's brush like a #1 or #2. If the scratch has gone throughthe finish and the stain, you can mix the shellac with alcohol soluble dyes or pigments tomatch to original color. White water spots can be treated the same way, but usually onlywith straight alcohol. Padding or brushing a coat of shellac and then rubbing it out likeabove restores the finish so that it looks even. If you're not sure whether the originalfinish is shellac, a simple test will confirm this. Dab some alcohol on an inconspicuousarea such as behind a leg. If the finish gets tacky, it's shellac.

If you're not confident in your abilities for the above repair techniques, a simplecleaning with mineral spirits or naphtha, followed by a light coat of paste wax improvesthe look of the finish quite a bit.

Jeff Jewitt owns and operates Homestead Finishing Products – featuringhard-to-find traditional finishing products. 5 Grades of dry shellac, oils, varnishes,brushes and their own exclusive line of dyes make Homestead Finishing Products a must forevery restorers supply needs. Excellent technical advice. Please contact us by:

Homestead Finishing Products
PO Box 360275
Cleveland Oh 44136-0005
Phone: 216-631-5309

Also available are Jeff’s Book Hand Applied Finishes, and two videos, Coloring Wood and Applying Topcoats – winners or the 1997 Stanley Award for best How-To book and video.

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