By J Jewitt
Prior to the introduction of shellac as a finishing material in the early 1800's, the traditional means of finishing furniture to a high gloss was accomplished by applying beeswax in thin layers with a cloth and then polishing it up to the desired gloss. These wax finishes did not wear well and were easily damaged by water and abrasion. The technique of applying shellac by rubbing it on the furniture with a cloth pad or "French Polish" is generally regarded to have begun around 1810-1820 in France and its acceptance as the favored finish for fine furniture spread quickly to Britain and throughout the rest of Europe. In France, the method used fine pumice stone mixed with the sawdust of the wood to fill the pores so that a glass-smooth finish could be obtained. In Britain, polishers used plaster mixed with various dry pigments to fill the pores. Then linseed oil was applied to the wood to bring out figure. Subsequent thin coats of shellac were applied with a fad or rubber (a cloth pad). The result was a finish of great depth and clarity.
French Polishing quickly spread to America but with some variations. Information on the early technique is scant, but a finishing book published in 1827 describes the general technique. The process omitted the pumice or plaster steps to fill the pores. Instead, a size of dilute animal hide glue was brushed on open-grained woods like walnut and then smoothed with glasspaper (the equivalent of our modern sandpaper) when dry. Then a linen rag with a flannel core was used to apply the shellac in circular motions over the entire piece of wood. This was repeated several times until a suitable finish was obtained. * Source - The First American Furniture Finisher's Manual- A Reprint of "The Cabinet-Maker's Guide" of 1827. ed. 1987 Robert D. Mussey, Jr. Dover Pub, New York.
There is no question that shellac remained a favored furniture finish in America from the early 1800's up to its displacement by cellulose-nitrate based lacquers at the end of World War II. While brushing and spraying shellac became the favored applications, the method of "padding" shellac with a cloth has continued to the present day as a easy and practical way to apply shellac. In this article I'll demonstrate the basics of how I pad shellac in my cabinet-making and restoration business.
Padding shellac is a low-tech process that is perfectly suited to the professional and amateur finisher. The advantages that it offers are numerous. First, the process uses shellac, a non-toxic, FDA approved natural resin. The carrier for shellac, ethanol, is relatively non-toxic (ethanol is the alcohol in liquor) and the fumes are not unpleasant . Secondly, shellac dries fast, so dust does not pose a great problem and shellac finishes can be done rather quickly, usually in several days. Third, it is a much easier technique to master than French Polishing. Lastly, shellac is a good-looking, durable finish that can be easily repaired if damaged.
The materials for padding shellac are inexpensive and easy to obtain through most finishing companies. (See Sources). They consist of shellac, denatured ethanol, padding cloth, and a drying oil such as boiled linseed oil or tung oil.
Shellac -- I prefer to make my own shellac solution from dry shellac flakes. Using fresh shellac avoids one of the classic complaints against shellac as a finish - it won't dry. Shellac is comprised of organic acids which react with alcohol in a chemical reaction called esterification. This gradual reaction produces esters which are gummy substances that inhibit the drying of the shellac. Although it's possible to use pre-mixed shellac, any liquid shellac older than 6 months should be tested for possible drying problems. To do this, place a drop or two of the shellac on a piece of glass. If it's not dry to the touch in 5 minutes, don't use it. You can use pre-mixed shellac but this is only available in orange or white (chemically bleached). There are a wide variety of grades to buy in dry form (see sidebar -- shellac) and if you make the shellac solution yourself, you are guaranteed a fresh solution.
Alcohol -- There are four suitable alcohol solvents for shellac - methanol, ethanol, propanol and butanol. Methanol is an excellent solvent, but it is toxic, so I avoid using it my shop. Ethanol is far better because of its low toxicity. Butanol has an odor which I find disagreeable so I don't use it as the main solvent. Propanol, the alcohol in rubbing alcohol can be hard to get in chemically pure form but its a good solvent for adding to shellac solutions as a retarder.
Padding Cloth -- The best cloth for applying shellac is sold as padding, trace, or French polishing cloth. The best cloth should be clean, lint-free and absorbent. The best product I have used comes in 12" squares and has a rumpled texture similar to surgical gauze.
Oil - Use either linseed oil or tung oil as both a sealer coat and to give greater depth to the finish. A very small amount is used and I have not been able to discern a difference between the two under the shellac finish. Always use boiled linseed oil.
No finish can hide sloppy surface preparation. On new wood, I plane, scrape and sand to 180 or 220 grit on critical surfaces like tops and sides. I also do as much surface preparation that I can on the project before it's glued up. I generally tape off tenons and other joints so that oiling from the next step doesn't contaminate the wood. On non-critical surfaces I leave the wood right off the plane. If the wood is to be colored I use water-soluble dye type stains and since these raise the grain, I knock down the raised fibers with maroon synthetic steel wool after the dye dries. I prefer synthetic steel wool because it won't cut through the dye on the edges. After the wood is smoothed down you're ready for the first step.
The purpose of this step is to seal the wood and give it greater depth. On re-finished pieces you can omit this step. Oils will accentuate the figure and deepen the color, particularly on curly maple and cherry. I have used a variety of oils, but I like linseed and tung oil the best. The amount of oil that is used should be very little. Perhaps a thimbleful per square foot is all that's needed. Apply just enough to deepen the surface of the wood.. Do not flood the surface with oil. Apply the oil with a clean soft cloth, rub the surface briskly and it will penetrate quickly. After several minutes, begin applying the shellac.
Make a pad from the padding cloth by folding it to the shape as shown in the photo. There should be no creases or seams on the pad bottom. Pour approximately 1 ounce of alcohol into the pad and work the alcohol into the pad. Then pour about 1/4 - 1/2 ounce of a 2 lb. cut shellac into the bottom of the pad. I like to keep my shellac in round squeeze type bottles. This simplifies dispensing into the pad.
Starting at the top of the board, bring the pad down lightly and drag it across the top, right off the opposite edge. Come in from the other side and repeat the stroke. Continue down the board in alternating stripes, with the grain of the wood. When you've reached the bottom, start again at the top - it will be dry enough for you to repeat the same sequence. Keep doing this until the pad is dry, then recharge the pad with more shellac. On tops, do the edges first after recharging the pad, then continue the same sequence as above. If there is a complex molded edge, conform the pad to the shape of the molding. Give the other parts of the piece a padding coat of shellac - aprons, legs, and sides. When the board is tacky and the pad starts to stick, stop and store the pad in a jar with a screw type lid.
After the first application of shellac it should be dry enough to scuff sand in approximately 1 hour. Using 320 grit stearated sandpaper (aluminum oxide mixed with zinc stearate as a lubricant), lightly scuff sand the surface of the shellac. Scuff sanding is a term for lightly sanding a surface - applying just enough pressure to scuff the surface. After this, smooth out the surface with maroon synthetic steel wool. Then apply shellac in the same manner as above to the other sides of all surfaces, undersides of tops, insides of carcasses, etc. When this is dry after an hour, scuff sand and wool these surfaces like above. Then glue the project together. Be careful to avoid excess glue and make sure that clamps are properly protected. If any glue squeezes out, you can pull it off like scotch tape after 30 minutes to an hour. Don't let it dry completely, it may pull off finish when you try to remove it.
The sequence is then repeated - starting at the top of the board and working your way down. The pad should glide easily over the surface and you should have an even coat of shellac on the surface. As the pad starts to dry out, you can switch from a stripe pattern to polishing in a circular pattern or a series of figure eights to get even coverage on the board. Replenish the pad with more shellac, (a good squirt from the squeeze bottle), and stripe the shellac on the board. Stop when the finish is tacky and the pad sticks. At this point, the surface should have an even shine, indicating a surface build of shellac. Put the pad back in the jar and let the finish dry overnight.
The next day, examine the finish. You should have an even coating of finish on the surface. If you are working with open-pored woods like walnut or mahogany, you'll see crisp outlines to the open pores. This level of finishing is appealing to some and you can stop applying shellac - simply skip to the rubbing out stage at the end and you're done. For surfaces that will receive a lot of wear and tear you may want to apply several more applications for maximum protection. Either way, the choice of whether or not to build up more finish is up to you.
If you want to apply more shellac, repeat the scuff sanding and wooling sequence as above and apply more shellac. Start with striping the board and then switch to circles as the pad dries out. Recharge the pad at least 3 or 4 times, and when the surface is tacky, stop. This step should take about 10-15 minutes on a 24" square surface. Let the piece dry overnight.
The piece is then smoothed with 320 grit stearated sandpaper, steel-wooled and then the shellac re-applied as before. Repeat this procedure until you've built the finish up to the film thickness that you want. You don't gain any added protection after 4 or 5 applications - only the aesthetic difference that thicker finishes bring. If you want, repeated applications of shellac with 320 grit sanding in between is a method that can be used to completely fill the pores in woods like mahogany and walnut. If the finish is thick enough, the surface can be leveled completely smooth, removing the outline of the pores.
After the final padding application, let the project dry for several days before proceeding to the rubbing out step below.
Rubbing out the shellac finish results in a smoother, better looking surface quality to the finish. The beauty of the padding application is that there are no brush marks or other surface irregularities to level, so this step usually goes very quickly. The first step is to take some 400 grit wet-dry silicon carbide finishing paper and level the surface of the finish. Then, using 0000 steel wool, squirt mineral spirits onto the pad, and then dip the pad into a can of paste wax. Working with the grain, I bear down fairly hard with the steel wool and rub the wax on the surface. I wait until it begins to haze, then I wipe off the excess and buff to a satiny sheen. If a higher gloss is desired, you could rub the surface with rottenstone mixed with mineral spirits before waxing.
If the piece is not subjected to a lot of wear and tear, a yearly re-waxing keeps it looking great. For tables, chairs and other high wear items, you can rejuvenate the finish by removing the wax with mineral spirits, then dry-wooling with maroon synthetic steel wool (000 equivalent). Then apply a light coat of shellac, let dry and re-wax.
SHELLAC, WHAT IT IS, WHERE IT COMES FROM, AND HOW TO USE IT.
Shellac is derived from a natural resin secreted by a tiny insect called Laccifera Lacca. This insect, about the size of an apple seed, alights on certain trees indigenous to India and Thailand and feeds off sap in the twigs of the trees. The insects secrete a cocoon type "shell", which is harvested by workers shaking the tree branches. In this form the resin is called sticklac and contains bits of twig, insect and other contaminants. The word "lac" comes from the Sanskrit lakh - which means one-hundred thousand.
The sticklac is then washed to remove impurities and a red coloring matter. At this point it may be either refined by hand or machine. Buttonlac is processed in India and is an impure form of shellac. It is reddish-brown in color and is sold in 1"-2" wide buttons, usually with the name of the dealer stamped on one side. Seedlac is another impure form and is processed further in India to better quality lacs, or exported to other countries for further refining. White shellac is made in this country by the Wm. Zinsser Company from imported seedlac which is dewaxed and then bleached by bubbling chlorine gas through it. This yields a colorless shellac solution.
The best shellac grades are rated by color and impurity content. The best grades are the Kusmi and Golden Bysaki crops and are usually shipped to Europe where they are further processed to yield dry shellacs such as Behlen "Super Blonde".
Many mail order companies sell dry shellac according to color and wax content. The most common shellac sold is #1 Orange and usually contains 4% wax content and is a brownish-orange color. Dewaxed shellacs can range in color from a dark-golden brown to a pale amber.