Home Forums Hunting & Shooting Gunsmithing Looking for some advice on a pure tung oil finish

For the first time I'm experimenting with pure tung oil and need some advice, or perspective as such. I'm refinishing a M2 Springfield stock and have been using pure tung oil as I want to stay as close to original with this project as I can. I am not a fan of boiled linseed oil. So far I probably have about six coats on this thing with the last few being thin "skim coats" that were put on with my hands and allowed to dry. It takes hours for the coats to dry (no surprises here) and within something like one hour the coat will dry up or soak in and go real dull. I don't want a built up finish nor one that looks as glossy as a pimp-mobile, but I also want to get the project done. Will the surface of the wood eventually become saturated and the finish stop turning dull or is this as good as it gets? What am I missing here as the dull sheen is a bit too dull for my taste and it just doesn't look any good? Should I top coat with something that will give a more satin look? Other than this problem pure tung oil is pretty cool stuff. Thanks much for any help.

You need to do a rottenstone finish after you get done with the oil finish.

Thanks. After sticking to it I think my skim coats are working out. There doesn't seem to be nearly as much oil soaking into the stock and the level of finish is still pretty low to the surface. The sheen is also turning into a nice satin. Since this is a milspec stock my goal wasn't to make a show piece, but rather something that fit within the context but at a grade a bit above average. I think I'll shoot for something a bit nicer on the next stock. I may be sold on tung oil.

Generally it's advised to fill the grain first. Spar varnish is suggested to get that done faster. Then sand to level the finish and then do your oil finish. And rottonstone (or whatever) to kill the glare. But I've done this myself only once or twice preferring other finishes.

I did sand with fine grain wet and dry paper, but with the tung oil and not spar varnish. I think I'm going to use your method on my next stock. Right now the grain is mostly filled, which is fine for what I'm trying to do. Thanks

And the "filled" grain will remain that way until the uncured oil down in the wood cures... oils shrink as they cure and those pores will telegraph very soon.

There is nothing tung oil does any better than linseed oil. "Boiled linseed oil" is simply low grade oil sold in hardware stores with lots of garbage added. Tung oil tends to be higher grade oil when purchased because none of it goes to "food grade," because many people are allergic to tung.

The finishing industry substitutes each for the other and many tung oil finishes have absolutely no tung oil in them.

There are many different ways to fill wood pores but none are as bad as sanding slurry left in them. Please make a sample board sometime with several different finishes, including wet-sanded slurry. If you do not see the loss in depth and luster you need to get your script changed. Shellac makes a great sealer for woods that will not be used in bad weather. It sticks to everything and about everything sticks to shellac.

Because oils used to be very expensive and often very old, hand-rubbing was a reasonable application method. Today, it is far easier to apply oil rather heavily and quickly. Then let cure for 10-15 minutes before wiping completely dry. Lots of coats can be applied quickly and will build to a beautiful luster.

Guess I should clarify - the advice I've read (Newell and others) is not to wet sand but brush on varnish to fill grain with just resin. No filler. Somewhere along the line I read it's ok to wet sand after the first coat as the "dust" is just resin. Thought is the fillers make the finish look muddy. Does to me. Never hurts to do a practice piece and make up your own mind on what works and looks good to you.

Yup...

Sitka knows.

Never had much luck with the heavy coat and wipe method. But that's me, don't have the technique right I'm sure. Why you make practice pieces.

Yes, I got that. I should have been clearer. I wet sanded the tung oil to create a grain filling "dough" from the oil and bits of saw dust. And yes I intend to use spar varnish and sand when dry on my next stock. I do believe both techniques have been used to success. Thanks again.

If you ever have problems with the "Apply Heavy, Wait, then Wipe" routine there are only two sources of issues, your oil or your rag. If your rag drags while wiping, you waited too long. If pieces of your rag end up in your finish you need a different fabric, old bedsheets work well. If it takes too long to build wait a little longer before rubbing dry, or learn to be more patient.

Old time gunsmiths got away with sanding slurry filling because they usually used much better wood with very fine pores.

That dough you speak of is what degrades a quality finish...

I like the procedure of first coat being cut with mineral spirits 1/1 allowing the mixture to soak in deeper. 2nd coat 2/1 and wipe dry after an hour or so. 3rd coat straight tung oil applied in thin coat. Wipe dry. 4th-6th coats usually 24 hours curing, wet sand very lightly with 800 grit. Finish coat. Wipe daily for a couple of days to remove any residue or bleeding of finish. Let cure for a week or more and finish with Johnson's paste wax. Week later with a coat of Renaissance wax.

Didn't know that. Thanks again

Sounds good. Thank you

Please make a sample board with your finish on one side and and the same finish on the opposite side but leave out the mineral spirits. Then cut the board in half, wait a day and look at the difference in penetration. Solvents improving penetration is a myth. And they create issues in other ways.

So you recommend not cutting tung oil with mineral spirits?

That is correct. Solvents seem to make finishes thinner, but the basic molecules are still the same size and the solvents simply run away from the finish... basically the wood acts like a filter. The reason for waiting a day after cutting the sample board is the wood is often still wet with the solvent and the finish looks to have penetrated more deeply. It doesn't.

Interesting. I never thought of it like that.

Sample boards will show you all kinds of things...