Restoration Workshop: Padding the truth

The most popular technique for applying shellac is French polishing, or padding, and it is this method I will devote the bulk of this space to.

Shellac is available in liquid form in most hardware stores and has a shelf life of about six months. If you use this premixed shellac, there is no way to know exactly how old it is when you buy it. Before using it, rub a thin layer onto a scrap piece of wood. If the shellac is not dry in five minutes, don’t use it. Shellac that is too old will take forever to dry and very old shellac may never dry. Shellac is available in flake form from Lee Valley, as is the thinner for dissolving it. In their dry state, flakes have an indefinite shelf life but once mixed with alcohol have the same shelf life as the premixed form. Try to mix only as much as you need. Denatured alcohol is often cited as the best solvent for shellac, but it’s hard to find in Canada, as it seems our government believes Canadians can’t be trusted not to drink it. The Lee Valley product, inspiringly named Shellac-Lacquer Thinner, is a blend of ethanol and isobutyl alcohol that works perfectly for dissolving shellac flakes. Wear the appropriate gloves and mask and apply the shellac in a well-ventilated area. Mix the flakes with the thinner the day before it is to be used, and give the flakes a periodic shake to help them dissolve.

There are basically three ways to apply shellac: padding, brushing and spraying. Spraying shellac is similar to spraying lacquer, as the consistency of both is practically the same. Because shellac dries so quickly, there are some special techniques for padding or brushing.

The key to successful French polishing is the pad. Fold a lint-free cloth (in this case, about two yards of cheesecloth) into a 12″ square. Then, fold the corners into the middle. Fold the new corners into the middle, and repeat until the cloth is a smooth ball that fits comfortably in your hand. The face of the pad must be free of seams or wrinkles. For added bounce, you can wad some upholsterer’s stuffing in the centre of the cloth and fold around it

Cloth Application

Padding is done by hand with a lint-free cloth. Fold the cloth into a smooth ball. Do this by folding the corners into the middle; repeat until the cloth is small enough to fit comfortably into the palm of your hand. The face of the pad should be tight with no seams or wrinkles. A technique used by some French polishers is to place a wad of upholsterer’s stuffing into the centre of the cloth and then fold the cloth around the stuffing. (I tried some dryer lint as a stuffing substitute. It worked well.)

Make the Cut

Shellac should be applied in thin layers of gradually increasing cuts followed by layers in decreasing cuts. (Remember: cut refers to the pounds of shellac mixed into a U.S. gallon of denatured alcohol.) I mix a portion each of a 1.5-lb. cut, 2-lb. cut and 3-lb. cut and apply them in the following sequences: 1-5 lb. cut, 2-lb. cut, 3-lb. cut, 2-lb. cut, 1.5-lb. cut.

Note: some finishers rub a very thin coat of penetrating oil into the wood before they apply shellac. They say it gives the finish greater depth. I don’t recommend using oils under shellac, as I believe that a layer of oil between the wood and the shellac will cause problems with adherence and shorten the life of the shellac.

Pour a little thinner into the back of the pad, not the face. Slap the pad into the palm of the other hand to spread the alcohol through the pad. Put some of the 1.5-lb. cut on the face of the pad and repeat the slapping motion.

Ready For Takeoff

Start at the far edge and work toward yourself. Pretend the pad is an airplane; with the pad held a few inches above the surface and at one end of the wood, land the airplane and taxi it to the end of the wood surface, going with the grain, and right off the edge. Reverse direction, and repeat as above. Continue this pattern, covering the entire surface. By the time you cover the surface once, the shellac should be dry enough to start again. When the pad gets sticky, refill it with shellac and repeat the application. Do this for about 15 minutes. Wait an hour and repeat the process using the next cut in the sequence. Some people wait a day between cut applications, and some lightly sand with fine (400 grit or finer) sandpaper between applications. I run my hand lightly across the surface once it’s dry, and if the surface feels a little rough, I sand; if not, I don’t.

After the last layer of the sequence has dried, I go over the surface one last time using a 1-lb. cut. The last one or two times over the surface I just squirt a little thinner into the face of the pad. This last procedure should even out any ridges in the finish.

Buffer Zone

Once this last application has thoroughly dried, rub the surface down with some rottenstone, white oil and a clean cloth. Then apply a protective wax finish. A hard wax will buff out to a higher gloss than a soft wax, so choose your wax with this in mind. Also, the softer wax will have to be reapplied more often than the harder wax.

Brush Application

To apply shellac with a brush, use only the 1.5-lb. cut or thinner, otherwise the shellac will not flow out properly before it begins to dry. Use a good nylon brush, 2″ wide or smaller. Apply at least five coats, letting each coat dry in between. Sand between coats if desired. After the final coat has dried, sand the brush strokes smooth; apply wax and buff as above.

To restore a shellac finish, first remove dirt with Murphy’s soap (follow the directions on the bottle, do not make the soap too strong). De-wax the surface with odorless mineral spirits (sold at Canadian Tire). Finally, apply a 1-lb. cut of shellac. One application is all that is necessary. This will amalgamate and restore the surface layer of the finish.

If the piece you’re restoring is in need of regluing, try disassembling the piece, taping off the joints and applying the shellac before regluing. Wait for the shellac to dry thoroughly, remove the tape, reglue and reassemble. Any squeeze-out should pop right off the finish.