Tung oil coats intervals/thinning

[DruBokkens]

Hi, I'm preparing for a wood finishing project and decided on pure tung oil after learning some about different oils. Maybe a bad choice but I'll have to find out. First of all, I'm going to use the oil on a slim, long piece of hickory heartwood. I assume tung oil will penetrate it, but I read that some guys thin each tung oil coat (apart from the last one), just to a different degree, to maximize penetration. First coat 3 parts thinner to 1 part oil, then 2 to 1, then 1 to 1, and finally pure oil. Would it be effective, or rather damaging to the previous oil coats?

I also read that I should allow at least 1 week between each coat, but I don't get how does it apply to the old oil finish recipe that everyone brings up, that says "once a day for a week, once a week for a month," and so on. In that case, should I apply the first 5 coats within 24h from each other instead a week apart? If someone experienced in oil finishes could clarify this a little confusing part, I'd be grateful.

[wtnhighlander]

One key to a good oil finish is to avoid over saturation..I made that mistake, and it was months before oil stopped oozing out of the pores in the wood. Boiled linseed, in my case, but I'm sure the principle applies to pure tung.

[Ronn W]

Thanks, Highlander you just answered a question/problem that I have experienced and I didn't even ask the question.

[Eric.]

We need Trip for this question.  I pelted him with tung oil Q&A months (years?) ago and he had great answers, of course.  Just like everything else....you don't realize something is a wormhole until you hear Trip talk about it.  There's a LOT to learn about tung oil.  I wish I could regurgitate the info I was given.

[Brendon_t]

18 hours ago, wtnhighlander said:

One key to a good oil finish is to avoid over saturation..I made that mistake, and it was months before oil stopped oozing out of the pores in the wood. Boiled linseed, in my case, but I'm sure the principle applies to pure tung.

I've had the exact same results, stupid me on dyed red oak which might as well be called a sponge with all the pores. The door looked like a fat guy in the sauna sweating from every square inch. 

[DruBokkens]

One experienced guy I asked, said that thinning it doesn't improve penetration, only spreads the oil molecules further apart, thus making the oil distribute unevenly, and told me I should use it in pure form and stick to the old recipe, applying once a day for a week, once a week for a month, once a month for a year and then once a year forever after that.

What I'm wondering is; on things like gun stock that need to be handled on a regular basis, is it safe to handle, say, once the weekly application dried? Surely you don't have to wait for a year to safely handle an item undergoing oiling?

[RichardA]

Why use an oil that takes so long to be useable?  Why not use an oil that dries quicker and harder!  And you can put a finish on it that will last as long as you want it to!

[wtnhighlander]

One key to a good oil finish is to avoid over saturation..I made that mistake, and it was months before oil stopped oozing out of the pores in the wood. Boiled linseed, in my case, but I'm sure the principle applies to pure tung.

I've had the exact same results, stupid me on dyed red oak which might as well be called a sponge with all the pores. The door looked like a fat guy in the sauna sweating from every square inch. 

Not meaning to hijack, but what project did you make with dyed red oak?

One experienced guy I asked, said that thinning it doesn't improve penetration, only spreads the oil molecules further apart, thus making the oil distribute unevenly, and told me I should use it in pure form and stick to the old recipe, applying once a day for a week, once a week for a month, once a month for a year and then once a year forever after that.

What I'm wondering is; on things like gun stock that need to be handled on a regular basis, is it safe to handle, say, once the weekly application dried? Surely you don't have to wait for a year to safely handle an item undergoing oiling?

I wouldn't use such a slow drying (and soft curing) finish on a gun stock. Something like Birchwood Casey Tru-oil gunstock finish is more suitable, and dries to a hard finish. It is linseed based, but contains a 'proprietary modified oil', (a varnish) that makes a more durable film.

[DruBokkens]

Doesn't tung have better water resistance than linseed-based ones? I'm trying to find an oil-based finish for a hickory stick that will need to be protected when using in the rain and on humid mountain days, also protected from acidic pH of sweaty hands. Thus my leaning toward pure oil finish. However, does it mean it will take 6 months before the item can be handled? I can wait 6 weeks unless that's not an option with tung?

[wtnhighlander]

You can handle the stick 8 hours after applying a coat of oil, so long as you don't saturate it. Hickory shouldn't soak it in like red oak, either. I would wipe it on pretty hevy with a rag, wait 5 minutes, then wipe it free of excess. Wait a day and repeat until you are happy with it. For a piece that will be handled that muxh, I would for sure wet sand the oil with 400 or 600 grit paper before wiping it off. The end result is incredibly "touchable".

[DruBokkens]

Thanks a lot for the advice, I will definitely do that. Is filling the pores a must, from a grain-sealing point of view? Doesn't bother me if the surface isn't perfect, unless oiling on open pores makes the wood less protected?

[wtnhighlander]

The wet sanding fills the pores with a slurry of wood dust & oil. That's what make it so smooth.

[DruBokkens]

I see, makes sense. Good to learn something new, thanks for sharing all the info with me. By the way, wet-sanding on fresh oil before wiping, I still have to use some water on the sandpaper, correct? Same goes if I was wet-sanding on tung-based varnish, right?

[wtnhighlander]

No, just sand the wet oil. By wet, I mean mop it on heavily, enough to puddle on horizintal surfaces. Go over it with the paper, then wipe off the excess. This doesn't work well on wood with huge open pores, like red oak, but tighter grain works great.

[DruBokkens]

Sounds good. And thanks again for sharing your knowledge.

/edited:

One more thing. What I need to achieve is a smooth finish, not tacky, which leads to my question: Does oil+resin varnish make a tacky finish? I know a pure oil one makes a smooth one, but I wanted to try an oil+resin marine varnish. However, on a practice sword, if I choose the wrong finish and end up with a "sticky" surface, I'm done for and I can toss the piece and start all over, because it's going to kill the hands of a user.

[wtnhighlander]

I'm not sure what you mean by 'tacky'. Any finish should cure hard and smooth, some take longer than others. If you mean will it build a surface film, then yes. However, you can control that by how many coats you apply. I think an oil+varnish blend like danish oil leaves a very natural feeling wood surface, but with enough coats, even that will build a film that is likely to create friction in a user's hands.

[DruBokkens]

Yes, high friction against the hands is what I mean and what I need to avoid, thus I was curious if addition of resin in a tung-based varnish would make it especially likely to give a surface higher friction because I'm looking for a natural, smooth finish. Since the stick will be exposed to humidity and sweat, I was advised to try marine varnish for ultimate water resistance, but not at the cost of friction. In wooden training weapons, it's a different kind of a challenge—how to make it 100% water-proof without friction. However, I understand that it may only be a matter of how many coats.

[DruBokkens]

Thanks for the info, that makes more sense.

[wtnhighlander]

You aren't going to get much water resistance without a film that increases friction on sweaty hands. I'd use an oil finish (pure oil or danish), and not try to build a film.

Another option is to soak the wood with mineral oil, like a cutting board, then follow with a beeswax polish. The oil prevents moisture from soaking in, the wax keeps the wood from feeling greasy. Clean and re-apply often.

[DruBokkens]

In that case, if I coated it with, say, good tung-based marine varnish that includes resins, several coats but not enough to build extreme friction, am I wrong? I figure it'd be hard to overdo even with several coats. With pure resin-based sealers I'd worry more about reaching too high friction, but not tung+resin.

[wtnhighlander]

I have no experience with any oil + resin product, outside if Watco Danish Oil. I know with that product, I have applied 6 or more coats, wet sanding each @ 600 grit, and produced a super-silky surface that did not have a VISIBLE film. I have no idea how many coats are required to produce such a film. In my case, the wood feels extremely smooth, without any friction/tackiness that a polymer film coating normally has. I doubt this finish would protect the wood from daily use in sweaty hands, but it shouldn't cause excessive blistering, and the Danish Oil is easy to clean and re-apply as needed.

[DruBokkens]

Like you said, I'll try 2-3 different types and see. I'm really curious about the results of a Waterlox marine varnish (tung, phenolic resin, ester gum). Wondering if a more flexible finish like that, would work better with regular impacts and vibrations of hickory, in the long run, as opposed to harder interior finish? Getting pretty crazy-technical here, probably couldn't tell a difference between them anyway.

[TheFatBaron]

You don't want a film finish on your weapons. Save yourself the trouble and just do 3-5 applications of tung oil or BLO. The film finish won't hold up under any impact, and the amount of water your hands actually put onto a weapon will do no damage to the wood itself. On the other hand, the film finish will give you a ton of blisters and a miserable feel.

[DruBokkens]

I don't want to achieve a film at all, for that reason. Don't you think that tung with some resin can combine both worlds and give a little more protection for a lot of outdoor practice in various weather, but without forming a film? Even if I don't apply enough coats for it to form, and sand it? Have you seen anyone try a marine varnish anyway? I know that they always just rub-oil the swords, but pure tung alone doesn't make it water-proof.

[wtnhighlander]

The marine / outdoor varnishes I have experience with form a film in just one coat. A tacky one, at that. Marine varnish is NOT more water proof, it is more flexible to avoid flaking off when the underlying wood moves.