I got a call from a fellow who made a Sam Maloof-style chair and screwed up the finish using Maloof’s formula. I thought, how can you screw up a Maloof finish?
Maloof combined three products – polyurethane, linseed oil and tung oil – to give him the look he liked on his chairs. Then he wiped on and wiped off several coats of the finish, rubbing each coat with his calloused hands (kind of like rubbing with fine steel wool, Scotch-Brite or sandpaper) to make the finish feel very smooth.
Of course, we don’t know if Maloof used 100-percent tung oil (real tung oil) or one of the many mislabeled “tung oils” on the market, which are actually varnish thinned about half with mineral spirits (paint thinner). We don’t know, but it wouldn’t really matter much because it would still be an oil/varnish blend either way. So it couldn’t be built up because it wouldn’t dry hard. The thinned varnish would add a slightly higher shine than the 100-percent tung oil, but it wouldn’t be very noticeable.
Anyway, the caller had not paid close enough attention when he bought his polyurethane; he used water-based polyurethane instead of oil-based polyurethane. Water and oil don’t mix, so the finish didn’t dry well or look right. It was gummy and there were blushed, or off-white, areas.
The point of this story is not to solve the problem. That’s easy. Somehow, enough of the finish has to be removed with solvents, strippers or abrasives to create a surface that can then be finished with the correct mixture.
The point is to caution you about the labeling of water-based finishes – actually the labeling on all finishing products. Manufactures are often not user-friendly when it comes to their labeling.