A friend called with a finish question. He had just made a guitar in a guitar-making class and wanted to know the best finish for it. He began with the statement that he didn’t have a spray gun and didn’t want to use aerosol lacquer because he didn’t want to stink up his house. So right away he eliminated about half the finish possibilities because they dry very rapidly so they need to be sprayed.
Then he hit me with a possibility I had never heard of or thought of: Tru-Oil, usually sold as a gunstock finish. I wrote about Tru-Oil in the November, 2016 issue of Popular Woodworking (#228). He had learned in his class that many guitar makers, who didn’t have spray guns, used Tru-Oil.
As I reported in the article, I believe Tru-Oil is a polymerized oil. This means it has been partially cured by cooking in an oxygen-free environment at very high temperatures before being put in the container. The cooking makes it cure very rapidly when exposed to the oxygen in air. It also cures very glossy after several coats, which is what my friend wanted on his guitar.
The one caution I have is that gunstocks have a considerably smaller surface area to be covered than guitars, so I suggested to my friend that he practice applying a coat on a piece of plywood with a surface area about as large as his guitar to get a feel for the finish.
The method of application is the same as for all oil finishes. Wipe or brush on, then wipe off the excess before it dries. With Tru-Oil it doesn’t have to be wiped completely damp-free like other oils, because it dries hard when applied thin.
– Bob Flexner