We use a lot of finishes in our workshop, from soap to shellac, but the one we recommend for beginning finishers is one we mix up ourselves.
It’s what Bob Flexner would label an oil/varnish blend. We just call it our shop finish.
During the last 20 years, I have developed some preferences as to the raw materials I use, but feel free to ignore those. Almost any brand of raw material will work. Here we go:
1 part Minwax Helmsman spar urethane, satin sheen
1 part boiled linseed oil
1 part odorless mineral spirits
Mix up the three liquids in a mason jar and you are ready to go. Apply it in thin coats with a clean cotton rag. Wipe it on and continue to wipe until the coat is as thin as possible. There should not be a visible puddling or pooling of liquid anywhere. You are wiping it almost dry.
Let the finish dry (it usually takes a couple hours). Use an extra-fine sanding sponge (usually #330 grit or so) to remove any finishing nibs. Apply another coat and repeat the process until you achieve the look you want. Two coats is the minimum for me and is what I use for workbenches and shop appliances. Furniture usually gets three or four. I have used as many as 10 for a customer who wanted a more plastic look.
Why This Finish?
The varnish offers a bit of protection against spills and stains. It’s not a thick film such as lacquer or a built-up shellac finish. But it does offer enough protection for a chair, bookcase or cabinet. Tabletops, which live a hard life, usually need more protection.
The boiled linseed oil offers a little color and will continue to add color as the piece is exposed to oxygen and sunlight. I like this yellowing. It’s what old furniture looks like.
The mineral spirits thins the varnish and oil, making it easy to spread the shop finish out to a thin and even coat with great ease.
Why These Raw Materials?
I prefer the Minwax Helmsman spar varnish (satin sheen) for a couple reasons. It’s easy to get at most home centers and neighborhood hardware stores. Its major competitor (here in the U.S.) is Varathane Spar Urethane. The Varathane works fine, but it smells a little stronger and takes longer to dry (usually an extra hour or more in my experience). It also gives a milky appearance to the mixture, though that doesn’t seem to change the look of the finished object.
I don’t have a preference for which boiled linseed oil I use.
As to the mineral spirits, I always strive to use odorless mineral spirits. It costs more but has fewer volatile organic compounds (VOCs) and almost no smell.
Aside from the protection that this finish offers, I like the low-sheen, hardly there aspect of the finish. It looks like wood does when it has been freshly planed. To your fingers, it doesn’t feel like the wood is wrapped in plastic. And it’s difficult to mess up when applying it. I’m sure it’s possible to mess it up, but I haven’t seen it happen yet.
— Christopher Schwarz