After cooking the soap concoction and letting it cool for 24 hours, it became opaque and thickened to a mayonnaise-like consistency. Today I used it to finish the top of a worktable that is based off examples shown in the Tacuinum Sanitatis, a health book from the Middle Ages.
My goal with this worktable was to give the top what some people call a “scrubbed finish” with a painted base below. An authentic scrubbed finish is really no finish at all. It is the result of years of washing – just bare, almost-bleached wood.
The finish is so prized by some collectors that it is routinely faked by some dealers. (Or so I am told.)
Applying the mayo-like finish is quick and easy. It spreads easily with a rag. The water soaks into the wood or evaporates quickly, leaving a bit of a hazy sheen on the wood. A clean rag wipes off the excess on the surface. It takes about 5 minutes total to apply a coat of finish to the top shown.
After the soap dries, it is indeed a dead-flat finish. Unlike other users, however, I didn’t experience any raised grain on the tabletop; my guess is that is because I didn’t use any sandpaper. The top is right off the jack plane. Even so, I sanded the finish lightly between coats with a #320-grit sanding sponge.
After four coats the top is very smooth and soft. Just what I wanted.
I’m going to experiment more with a soap finish in the coming months. I like how it can be used to produce a variety of sheens depending on the amount of water you add to the flakes. I also really like how simple it is and how difficult it is to mess up – perfect for the beginner. The added bonus is that it is much less toxic than many solvent-based finishes. I have enough volatile organics in my shop.
— Christopher Schwarz