What To Know About French Polishing

Some people approach furniture finishing as a trade, while others consider it an art. It’s actually both. But if you devised a scale between these two endpoints, French polishing would be close to the art end. It’s similar to inlay in cabinetmaking — a detail-oriented process that produces beautiful results if you do it right, with emphasis on the “if.”

Most of my work as a furniture finisher focused on production; I had little time for an arcane procedure developed in France in the late 18th century. I gave it a go a few times, though.

Because I love wood for its texture, coloration and overall sensory appeal, I learned to appreciate the sophistication of French polishing as a finishing technique. More than one woodworker claimed it’s simply the best wood finish possible, and I wouldn’t disagree.

When properly done, French polishing leaves an ultra-thin finish coat that lacks the plastic appearance of modern coatings like polyurethane and even lacquer.

The shellac you use for French polishing comes from the lac bug (Laccifer lacca), native to India and other parts of Southeast Asia. Chinese and Japanese craftspeople traditionally used similar bug excretions, as well as tree sap, to make lacquer. But these days, most lacquers are synthetic.

If you want a truly natural film finish, shellac is the way to go. If you want it to look stunning, French polishing is the best way to get there.

What Is French Polishing?

French polishing is a wood finishing technique that involves applying multiple coats of shellac with a cloth.

To get the best results, each coat needs to be ultra-thin. The finish builds up with each coat, and there’s no limit to the number of coats you can apply. Some enthusiasts of this technique have been known to apply as many as 100 coats.

One of the main determinants in the quality of the finish is the shellac itself. For a master of French polishing technique, mixing the shellac in a solvent is part of the job. Shellac comes in dry form as flakes or buttons of varying qualities and hues that range from clear to yellow and brown. The solvents are typically denatured alcohol or ethanol.

The Pros and Cons of the French Polishing Technique

The main drawbacks are that it’s time-consuming and requires practice and skill. For an enthusiast, that’s part of the fun, but it can be a deal-breaker for someone looking for a utilitarian finish.

On the other hand, French polishing requires few tools and materials, which is a plus. But shellac itself can be expensive, especially if you buy flakes and mix your own.

Here are some pros and cons of the actual finish:

Pros

• Durable: While not as impact-resistant as a modern finish like polyurethane, shellac can hold its own under heavy use. It was a popular floor finish in the 18th and 19th centuries.
• Flexible: Shellac can expand and contract along with the wood, which helps it resist cracking and flaking.
• Nontoxic: The insect secretions that form shellac are intended as food for larvae. While not particularly nutritious for humans, they’re harmless.

Cons

• Non-curing: A shellac finish will soften if it comes in contact with alcohol and some ammonia-based cleaners. Spilling your cocktail will ruin a shellac finish.
• Vulnerable to moisture: White rings will form if you leave a glass of water on a shellacked table. Even high humidity can turn shellac cloudy while you’re applying it.
• Vulnerable to heat: If you set a hot pot or pan on a shellacked surface without a trivet, the finish will blacken.

How To French Polish Furniture

Tools and materials

• Dried shellac, denatured alcohol and a mixing jar, or a can of premixed shellac;
• Old T-shirt;
• Large eye-dropper;
• Olive oil;
• 100-, 120-, 150- and 220-grit sandpaper.

Steps

1. Prepare the wood: Sand the wood to a smooth surface finishing with a fine grit like 150 or 220. If you’re finishing wood with an open grain, like oak or mahogany, fill the grain with pumice or a wood grain filler to get the smoothest possible surface.
2. Prepare the shellac: Mix the dry shellac with alcohol in a glass jar or container; avoid metal or plastic. If you’re using premixed shellac, thin it down with alcohol in a jar. Premixed shellac is generally too thick for French polishing.
3. Make an applicator: Cut a 6- by 6-in. square of material from a T-shirt and fold it over to form a ball. Cut a larger square from the T-shirt, wrap it around the ball and tie it off.
4. Load the applicator: Using a large eye-dropper, squirt shellac through the base of the cloth pad. Keep squirting until the bottom stays wet, then add a few drops of olive oil to prevent the cloth from sticking to the wood.
5. Apply the shellac: Rub the wood in a circular motion with the loaded applicator, starting with small circles in the center and gradually working to the outer edges. If the applicator dries out, move it toward the outer edge before removing it and adding more shellac.
6. Apply multiple coats: Let the shellac dry for 10 to 20 minutes, sand lightly with 300-grit or finer sandpaper to remove bumps, then apply another coat. Keep doing this until you’re satisfied with the finish.

Best Uses for French Polishing

Because of shellac’s vulnerability to heat, moisture and solvents, you shouldn’t French polish a table that’s going in the kitchen or dining room. On the other hand, if you have an antique dresser or table you’re hoping to flip or upcycle and you can keep it away from moisture and alcoholic drinks, nothing will make it look as good as a French polish finish. And the finish should last.

Finishing musical instruments may be the best use of the French polish technique. Luthiers, the string instrument makers, prefer French polish over other finishes because it can be applied incrementally in thin coats. That controls the degree in which the finish affects the acoustical properties of the wood.

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