Five reasons to lather on this traditional Scandinavian polish
Soap finish, a shop-made polish with a long history of use in Europe, is becoming increasingly popular among furniture makers here in the States. It’s environmentally friendly and safe to use without PPE, and although it only provides moderate protection and durability, its simple formula, silky finished feel, and easy reparability tip the scale in its favor for many applications.
I first learned of using soap as a wood finish when I was studying fine woodworking at The College of the Redwoods. One of my fellow students hailed from Sweden, where the use of soap finish on floors and furniture is more common, and he used it to finish a dining table that was sure to see plenty of daily use. I’ve been enamored of this simple mixture ever since. It may seem counter-intuitive, but heavy traffic surfaces are where this soft finish really shines. Dirt and grime are easily cleaned up with the same soap mixture, renewing the finish, all in one step.
Perhaps the most compelling advantage of shop-made soap finish is its convenience and affordability. All you need to make this sudsy sealer is a bar of pure Castile soap, some boiling water, and a little bit of time
Natural look and feel
If you’re looking for a finish that preserves the simple beauty of raw wood, soap finish is one of your best options. Once it dries, it causes little to no change in color tone or value. Although impurities in the soap or minerals in tap water could cause reactions with tannins in the wood, distilled water and high-quality soap will avoid this. And taking the final step to buff a soap finish will add a satin sheen to its appearance and provide a soft, silky feel to the surface.
A clear choice. Causing little to no color change once dry, soap finish preserves a raw wood appearance in comparison to other common finishes.
Easy to maintain, and repair
For day-to-day cleaning of soap-finished pieces, dust with a dry or lightly damp cloth. If you need to sanitize the surface, reapply your soap finish mixture: it also cleans the surface. If a stain requires sanding or a dent needs to be steamed out, attend to the trouble spot and reapply the soap finish locally, blending seamlessly into the surrounding areas. Add a fresh coat to projects at least once a year to maintain the protective properties of the finish, and buff the surface with a soft cloth to maintain its satin luster.
Scrub away the stain. While soap finish is resistant to water and alcohol, spills can leave a mark. Sop up excess liquid with a cloth and use an abrasive pad loaded with soap finish to scrub away any stains left behind. Wipe off excess suds and wait a few minutes before buffing the surface with a soft cloth.
Scrub away the stain. While soap finish is resistant to water and alcohol, spills can leave a mark. Sop up excess liquid with a cloth and use an abrasive pad loaded with soap finish to scrub away any stains left behind. Wipe off excess suds and wait a few minutes before buffing the surface with a soft cloth.
Inexpensive and convenient
A 4 oz bar of pure, unscented Castile soap will run you somewhere between $1.50 and $5 at your local pharmacy. Using a 1:1 mixture (instructions at right), I was able to apply three coats to a 3 × 5' ash dining table. Coverage will vary depending on your mixture, number of coats, and wood species, but it will never break the bank.
Safe and environmentally friendly
Fragrance-free, pure Castile soap contains no volatile organic compounds (VOCs). It cleans up with itself and water. It’s safe to wash down the drain, and soapy rags do not pose a combustion hazard. Working with soap finish is as safe as washing your hands.
Easy to make and apply
Soap finish is made by mixing pure Castile soap with boiling water. I prefer a 1:1 ratio by weight. First, shred the soap into flakes using a kitchen grater. Weigh out a portion of flakes into a mixing bowl; 1 oz is a good amount to start with. Pour the same weight of boiling water into the bowl. Mix until the flakes are all dissolved. I like to use a whisk chucked into a hand drill to whip the solution until it expands to several times its volume and soft peaks form. Let this sit, undisturbed, for about an hour until it has hardened to a soft solid. Then the finish is ready to be applied using a rag or abrasive pad, as shown. Sand between coats with 320 grit paper. Buff the final coat with a soft cloth for a silky satin sheen.
TIP: Customize your recipe. You can experiment with different soap-to-water ratios to achieve different consistencies. For easier mixing, try a thinner mixture, although you may need to wait a day or two—or place it in the fridge—for the mixture to gel up.
Grate the soap. Use a kitchen grater to convert pure Castile bar soap into flakes that dissolve easily in boiling water. I prefer buying and grating bar soap because of its wide availability, but you can also skip the grater by purchasing pure soap flakes in specialty stores or online.
Whip it up. Stir the soap flakes and hot water (be careful not to splash yourself) until all the flakes dissolve. I like to chuck a whisk into my hand drill and whip the mixture into a frothy foam. This method causes the mixture to expand to several times its original volume, so be sure to use a large bowl.
Lather it on. After you’ve given your mixture time to cool and firm up, apply the finish with a #0000 abrasive pad. There will be suds, but keep spreading the soap in the direction of the grain until the surfaces are coated. Wait a couple minutes before wiping away the excess.
