Heating Tung/Teak oil

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Blog entry by ocwoodworker posted 08-09-2010 06:51 AM 7471 reads 0 times favorited 15 comments Add to Favorites Watch

My local guru who I go to for advise, said to heat the tung oil to about 140 degrees and then apply it to my walnut table. Has anyone else done this? And if so what do you apply it with? A foam brush?

-- I'd like to believe Murphy's Law haunts my woodshop, because if it's Karma it would mean I had something to do with it. - K.R.

15 comments so far

View Don's profile


517 posts in 3125 days

#1 posted 08-09-2010 06:59 AM

It works fine at room temperature in my experience. What’s the point in heating it and risking a flash fire if it gets too hot?

-- Don - I wood work if I could. Redmond WA.

View ocwoodworker's profile


209 posts in 3057 days

#2 posted 08-09-2010 07:02 AM

I forgot to mention that the reason he said to do it like. He said was that as the oil heats up it, its vescosity goes down thus making it penetrate deeper. Makes sense, but I dunno….hmmm. Don you have a good point and yes my guru did warn me about it.

-- I'd like to believe Murphy's Law haunts my woodshop, because if it's Karma it would mean I had something to do with it. - K.R.

View Don's profile


517 posts in 3125 days

#3 posted 08-09-2010 07:17 AM

I’m sure that’s true but I doubt that the extra nano-inch of penetration is going to increase the protection of the wood enough to be worth the risk. I wouldn’t do it, I already have enough different ways that I could burn my shop down without putting a flamable liquid on a stove.

-- Don - I wood work if I could. Redmond WA.

View JuniorJoiner's profile


487 posts in 3492 days

#4 posted 08-09-2010 09:04 AM

my question would be why are you using tung oil on walnut? do you not find it blurrs the grain and colours and makes it look muddy?
if it is for a table my first thought would be a wiping poly for a high use item, or shellac for a lower use piece.
you spent time making the piece, so you have scrap. do a few samples , it is easier than scraping off a finish you are unhappy with. its really hard to scrape off a well penetrated tung oil.

-- Junior -Quality is never an accident-it is the reward for the effort involved.

View Howie's profile


2656 posts in 2975 days

#5 posted 08-09-2010 12:33 PM

As hot as it’s been here in Florida, I don’t have to heat the finishes,they are already “heated”.
I’ve used tung oil on walnut,cherry,pine and poplar and never seemed to have a problem. Maybe I need to look closer at the walnut.

-- Life is good.

View hObOmOnk's profile


1381 posts in 4180 days

#6 posted 08-09-2010 12:36 PM

Real tung oil and walnut is a marriage made in heaven – both durable and beautiful.

-- 温故知新

View Robb's profile


660 posts in 3986 days

#7 posted 08-09-2010 02:13 PM

I’ve used tung oil on walnut before (room temperature) and was pleased with the results. It was more of a matte finish than poly, but definitely made the grain pop in a pleasing way. I’ve never heard of heating it before this.

-- Robb

View JimF's profile


144 posts in 3345 days

#8 posted 08-09-2010 03:14 PM

If you’re going to heat oil or any flammable liquid, use a pan of hot water. Don’t put the flammable directly on a stove.

-- Insert clever tag line here

View Joe Watson's profile

Joe Watson

316 posts in 3599 days

#9 posted 08-09-2010 04:22 PM

i have someone i know that uses a hot oil method as well. uses a plastic bottle in a stew pot including water. the hot oil lowers the viscosity and allows for better penetration. and from what i am told it also lasts longer than if the finish was put on at room temperature. he also uses a wax on top of the oil afterward.

-- Got Wood?

View CaptainSkully's profile


1601 posts in 3611 days

#10 posted 08-09-2010 04:29 PM

Walnut finished with tung oil is beautiful. It’s my favorite finish for such a naturally dramatic wood.

Heating the oil to 140°F is an interesting thought, and using hot water is a great way to do it. I’d make two sample pieces, one hot and one cold, let them cure, and cut them in half to see how deep they penetrate. I did this with ammonia fumed white oak and was blown away that it went 3/16” deep. I think I’m going to give this a try next time I do a tung oil finish. Thanks for the info.

-- You can't control the wind, but you can trim your sails

View Kindlingmaker's profile


2656 posts in 3579 days

#11 posted 08-10-2010 06:20 AM

Open cell wood I could possibliy see doing this, (I use thinner) but closed cell woods, huuummmm…

-- Never board, always knotty, lots of growth rings

View CaptainSkully's profile


1601 posts in 3611 days

#12 posted 08-10-2010 07:14 PM

BTW, I use foam brushes on anything that isn’t sensitive to bubbles as part of the finish. I think the idea of tung oil is to flood the surface, letting it soak in, then wiping off the excess. Gel stains, oil stains, etc. are OK, but shellac and a lot of clear finish coats like Arm-R-Seal, polycrylic, etc. do bubble up annoyingly.

-- You can't control the wind, but you can trim your sails

View mrCello's profile


1 post in 2810 days

#13 posted 11-07-2010 11:34 AM

There ’s an excellent discussion of the chemical processes leading to the formation of the hard, water-resistant film that occurs during the application of drying oils, and with Tung oil in particular, by Steve Russell
in a forum about tung oil on lumberjocks posted by “brad”. (He has several posts in the forum, all worth
reading.) It gets a bit technical, but I learned a lot that was really useful. Pure Tung oil is very viscous, and is difficult to apply fresh Tung oil out of the bottle, especially over a large surface. Heating it naturally lowers its viscosity. A book on finishes I looked at recommended heating it to about 140 degrees (F). I use a double boiler on a stove top with the ventilation fan running to make sure vapors don’t accumulate. I wouldn’t use a brush, and a foam brush might be likely to break up and leave bits of foam everywhere due to the high viscosity of the oil. I’d use a rag, since you want the oil to penetrate the wood. Also, a point that that Steve brought up is that heating the oil increases its rate of oxidation, which is the beginning of the complex chemical processes that lead to polymerization and the formation of a hard film. It sounded from Steve’s post that the temperature needs to be significantly above 140F for this to occur (if I recall, more like 140C, which you probably don’t want to try yourself on a stove.) Companies sell polymerized drying oils that have been heated are are already polymerized or partially polymerized, and will take a lot less time to dry. But if you’re patient, you can achieve the same thing through natural processes, but it takes a lot longer. The best thing is to apply the oil in thin coats, working it into the wod
with a rag and a llot of elbow grease (frictional heating will facilitate oxidation and polymerization, I’d think.) For this reason, its REALLY nice to apply to turning projects on a lathe, since all you have to do is hold the rag in place and manage not to burn your fingers. Then let it dry. But it will take multiple coats if you’re not putting anything over the Tung oil like shellac or a varnish. Tung oil is great. I like it for most things a lot better than linseed oil. And if it isn’t going to get a lot of rough use, shellac over Tung oil is a striking combination. I haven’t used it on walnut, but I’d think it would work very well there. I use it a lot on mahogony, which is also a dark wood, but not as dark as walnut. I’d also think about finishing it with a final coat of paste wax, but make sure you use a dark wax on a dark, open grained wood like Walnut, since a white paste wax be leave little flecks of white embedded in the grain, which will be very noticeable against a dark background.

View ocwoodworker's profile


209 posts in 3057 days

#14 posted 11-08-2010 03:14 AM

Wow, Robert! Thanx for the input. I did heat it to 140 F using a crock pot. The first coat I used 50/50 with alcohol and then steadily increased to 100% by the 4th coat. Have you heard of “Japan Dryer” ? It was recommended to help speed up the process of drying. Or as you put it… to increase the polymerization of the tung oil. Thanx for the tip on using a dark wax. It never occurred to me.

-- I'd like to believe Murphy's Law haunts my woodshop, because if it's Karma it would mean I had something to do with it. - K.R.

View Snickare's profile


1 post in 25 days

#15 posted 06-23-2018 03:23 PM

I attended a woodworking school in Sweden. We applied what was essentially boiled linseed oil to elm. We used a home deep fat fryer to heat the oil to 100C. Yes, that is the boiling point of water, and just under the boiling point of oil. I wore flock insulated nitrile gloves, plenty of ventilation in the room. A natural bristle brush, just a cheap one.
Two applications. Between applications I sanded with a screen abrasive of 220 grit with a pneumatic disc sander (Mirka 5”) while the oil was abundant on the surface. After the second coat cooled to room temp. (10 minutes), I wiped it off with a clean rag.
The concept is the oil at high temperature not only penetrates deeply between the layers of wood cells, but the molecule of the oil is able to penetrate the cell walls of the wood.
I was dubious of the safety of this at first, but aside from the strong vapors and the danger of hot oil to human skin, I don’t think that there is much to worry about.
I believe that this can be used on any wood species, but I only tried it on elm, beech and ash.

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