How to apply pure tung oil as a finish?

[Michael Ray Smith]

I usually hang out on the Neanderthal board, but I have a finishing question. I'm going to try using pure tung oil (not a tung oil finish -- I've read enough to know the difference, and I know enough chemistry to understand what I've read) to finish a small project. Small enough that if it turns out to be a complete mistake, it'll be no big deal, but I'll have learned something in the process. It's a small box made entirely of curly maple -- so I don't have to worry about different species of wood behaving differently. I have pure tung oil I bought from Woodcraft not too long ago. I've experimented a bit with it already, so I have a feel for its viscosity, etc. It's in a plastic bottle, and I've been careful to squeeze the air out of the bottle before I put the lid on it to minimize oxidation.

For those who use pure tung oil and like it, I have a bunch of questions about the detailed technique. How do you apply it? How do you prepare the bare surface? Do you cut it with anything? If so, how much and with what solvent? What do you apply it with? Do you wipe off the excess? If so, with what? Do you sand between coats? If so, with what? How long do you let it cure between coats? Do you do anything to speed up the curing process? How many coats? Do you put anything on top of the oil finish (e.g., wax)? And anything else you might think I should know but haven't mentioned.

Thank you!!

[Steve Schoene]

Apply pure tung oil heavily and let it penetrate for something like 20 minutes. Let cure for at least 2 days, and then sand lightly with 600 grit, then repeat the process for a total of 5 or so applications until the finish is an even satin sheen. Don't try to rush the process or you could discover a "frosted" look in the finish that might appear several months down the road. Wax is a purely cosmetic decision. Thinning the tung oil is of no benefit. HOWEVER I recommend you give up the idea of using tung oil as a finish. It makes a lousy finish, with almost no protection against water stains. The finish oxidizes over time and in a year or so the sheen is likely to become dull. You will see almost no difference between the tung and a mix of oil (BLO) and varnish. This would give considerably more protection, and last a bit longer before need to be refreshed. You can mix the oil/varnish your self--equal parts oil, varnish and thinner works well, or you could use a manufactured Danish Oil such as Watco. The oil/varnish will need only about three applications, and each can be done only a day apart.

[Jerry Thompson]

I have heard all sorts Tung Oil subjects both pro and con. My wife finished a walnut clock with pure Tung Oil. It was heat polomerized and she put enough coats on it un til it developed a shee which she knock back to satin. This was Aug. 1977. Nothing else has been done to it except dusting. The finish is still as it was and lloks great,
We also mad a doll cradle for our grand daughter 15 years ago from cherry and had the same treatment and with the exceptions of childrens use marks on it it looks great except darker due to the aging of the cherry.
It is to the point I tell folks asking about Tung Oil I just tell the "Damn if I know."

[Michael Ray Smith]

HOWEVER I recommend you give up the idea of using tung oil as a finish.

I may well give it up, but I want to try it for myself first.

[Michael Ray Smith]

I have heard all sorts Tung Oil subjects both pro and con.

Me, too. I figure I have a better chance of it working if I follow the techniques used by those in favor of it.

[Prashun Patel]

I have used it on turned bowls. I prefer to combine it with sanding up to high grits. You can either dry sand, or wetsand. Personally, i prefer to add a little varnish to oil, but i apply it the same way. Wipe on, wipe off.

[Steve Schoene]

I agree that making your own tests is a good idea, in fact I recommend that one ALWAYS make full tests of any finish system proposed for a project. Much better to test on scrap than to have to scrap the project.