I have tried various methods of mixing linseed oil and tung oil in the past, but since the mid 80’s I’ve been using a product called Seal-A-Cell and Arm-R-Seal made by the General Finishes Company and available through mail order as well as from Woodcraft.
Since doing the first six seasons of Woodworks, this finish has been improved and no longer has the make-up stated in the show. I use two products starting with a sealer and finishing with a top coat. Company representatives state the sealer (which is clear but also available in different colored stains) is a blend of modified linseed oil, oil modified urethane, and alkyd resin, and dryers. The topcoat I use is called Arm-R-Seal and is now an oil modified urethane with dryers. The Arm-R-Seal is available in gloss, semi gloss, and satin.
A high quality finish starts with good surface preparation. This means thoroughly sanding the surface with 220 grit sandpaper or higher. I usually sand to 320 grit to bring out the clarity of the grain. Because of the time limitations of the show, we generally don’t demonstrate much sanding. After removing the dust (I use compressed air, if you don’t have compressed air, a vacuum cleaner and tack rags work well), I apply the first coat of sealer liberally to the surface allowing it to soak in for a few minutes and then use some soft rags and buff off all of the excess. This is important otherwise you will have resins that get sticky and leave an uneven surface. I let this coat dry overnight preferably at 70 degrees or warmer. A cold and damp environment can cause a finish to lack clarity and delay drying time.
The next day I thoroughly buff the entire surface (including the backs and bottoms of furniture which I finish to balance the piece and maintain equilibrium with 4 OT (0000) steel wool. This is the finest grade and I find that it really smoothes the surface. After removing the steel wool dust, I apply the first coat of Arm-R-Seal gloss. As a rule I always build the finish with coats of gloss whether it is oil, lacquer, urethane, etc. Then, if I want a semi gloss or satin sheen, I’ll use that for the last 1 or 2 coats. Keep in mind that the Arm-R-Seal dries faster so I usually just work smaller areas up to 12 square inches and overlap the finish. Again, I brush it on, let it soak in for a minute and rub the surface dry with a clear cloth. Let it dry and repeat the process.
I find that a total (including the sealer coat) of 4 or 5 coats usually creates a nice smooth finish that protects the wood while bringing out the beauty and depth of the grain patterns.
– David Marks, host of Wood Works.