Tung Oil

[JonathanF1968]

Hello! I'm curious about using 100% pure tung oil as a finish on some turned items that need to be food safe. Never used it before. A few questions.


1. Do you apply tung oil off the lathe? Directions on the bottle say to wipe it on and wipe it off. I wonder if there's a benefit to applying it on the lathe, and even using a little pressure to get it in, work up some heat, etc. But I'm used to using friction polishes, and so maybe this is a bad idea for tung oil?


2. Do you think a coating of beeswax on top of the oil would be a good idea, or again counter-productive?


I'm thinking, about three coats of the oil, possibly sanding with 1500 between the first two coats.


Any other tung oil turning tips? Which is a turner's tongue-twister.

 

[monophoto]

I normally use Tung Oil as an ingredient in either a 'long-oil varnish' (mixed with equal quantities of a good-quality spar varnish and turpentine) or a classic friction polish (equal quantities of lacquer and lacquer thinner). But I have used it alone, and also as a lubricant in wet sanding.

When used as a lubricant, I usually mix it 1:1 with turpentine. It forms a slurry with sanding dust that fills open grain on wood like oak, producing a smoother finish while also penetrating into the wood where it cures to form the first step in a water-resistant finish.

When used as a standalone finish, I do take the 'fat over lean' approach - the first coat is thinned 1:1 with turpentine, and then additional coats are full strength. This is a wipe-on/wipe-off finish - apply it generously, let it penetrate the wood for about an hour, and then wipe it off with a paper towel or a soft cloth. Allow it to cure for about 24 hours, and then repeat as desrired.

Let me emphasize that I'm referring to PURE Tung Oil. I use Hope's - there are other brands, but they are all pretty hard to find. I don't know anyone in my area who carry it, but there is a hardware store in a resort area that wife and I visit a couple of times a year who stock Hope's. There are a number of products out there that are called Tung Oil, but in fact are a form of Danish Oil in which the Tung Oil is mixed with varnish and other ingredients. Read the label carefully - if there is any suggestion that it contains mineral spirits, it's actually a blended product and not pure Tung Oil. Those are perfectly good products and I do use them - they just aren't pure Tung Oil.

After it has cured for a week or so, it's fine to buff and wax the surface. I would tend to use carnauba wax because it is harder and lasts longer than beeswax.

I typically use three applications. However, I am currently working on a goblet that is intended to be functional, and in that case I wet sanded with pure Tung Oil, and then will apply 6-8 thin coats of a long-oil varnish to the inside to assure that it is fully waterproof.

 

[Curly]

1.Yes the heat from the friction helps the oil cure.

2. It won't hurt but if you can let the oil cure a bit (days or weeks) before working in the bees wax. Reason is pure tung oil takes a long time to cure where the stuff mixed with solvents also has chemical dryers to speed up the process.

Reminder that the oily rags can self combust and burn up your shop. Submerge them under water or remove them from the shop and spread them out to dry outside.

 

[leehljp]

Pure Tung Oil is a slow curing finish and it is worth waiting on. But rushing it doesn't let it develop its depth of sheen in the wood.

My first experience with it was in Tokyo. Went to a Japanese Paint store and they had a can of pure tung oil labeled "Tung Oil" in English. The rest of the writing was in Japanese and I couldn't read it at the time.

I poured some on a platter and wiped it around and let it set until the next morning. The next morning, it was still wet. I scratched my head and wiped it off. I poured some more on it and spread it around. Next day, just as wet as when I put it on. A little aggravated, I wiped it off the the second time and re-applied. Next day, just as wet. I got frustrated and just set the platter aside and forgot about it. Two weeks later I looked at it and it had the best looking finish I had ever done. The walnut platter is still being used today.

I didn't learn until a couple of years later that by accident, I did exactly what was required of a great finish with pure tung oil.

 

[JonathanF1968]

When used as a standalone finish, I do take the 'fat over lean' approach - the first coat is thinned 1:1 with turpentine, and then additional coats are full strength.

Thanks for your thoughts.



Is it still "food safe" if you mix it with turpentine?


I did find some Hope's on Amazon. Came in today's mail.


--Jonathan

 

[monophoto]

Is it still "food safe" if you mix it with turpentine?

Turpentine is NOT a petroleum-based solvent. Instead, it is made by distilling the sap of pine trees - so its a vegetable extract. But it is still toxic.

I choose to use turpentine because it is a natural product, and smells better than mineral spirits.

The operative theory is that mineral spirits and turpentine are both 'food safe' once the volatile components in the solvent have evaporated.

 

[dogcatcher]

Is it still "food safe" if you mix it with turpentine?

Turpentine is NOT a petroleum-based solvent. Instead, it is made by distilling the sap of pine trees - so its a vegetable extract. But it is still toxic.

I choose to use turpentine because it is a natural product, and smells better than mineral spirits.

The operative theory is that mineral spirits and turpentine are both 'food safe' once the volatile components in the solvent have evaporated.

How about using citrus solvent? Per Real Milk Paint Company it is safer than turpentine.

 

[Wildman]

Pure Tung Oil, will protect wood if apply enough coats! I would go more than three coats! While Tung oil is a drying oil doesn't penetrate very deeply by itself so mixing with solvent/thinner(citrus, MS, Naphtha, Turpentine, etc) helps oil penetration and speeds up drying some what.

Even thinned Tung oil takes time to dry after each coat talking day or two! JMHO, while pure Tung oil might be food safe once add solvent/thinner maybe not. Just check out MSDS or SDS on solvent/thinner product want to use!

While like using Tung oil as a finish wouldn't use it on items want food safe.
I post this article by Jonathan Binzen, "Food-Safe Finishes couple times a year.

https://www.finewoodworking.com/2006/08/01/food-safe-finishes

My go to finish for food safe finishes simply mineral oil a laxative! Don't use baby oil or industrial mineral oil. Mineral oil is non drying but easily re-applied as needed by user of the item. My customers for salad mixing & serving bowls get a bottle of mineral oil!

 

[gtriever]

For food - safe items I also use the ol' home brew mix of mineral oil and beeswax. There are a lot of recipes for it on the web ; the ratio I use is 1 cup of Mineral Oil to 1 1/2 ounces of Beeswax.

 

[Woodchipper]

Birchwood-Casey Gunstock Finish is a refined (?) linseed oil product. It takes a while to dry. I would hang the gunstock from the garage door rail and check it. Lightly rub with 0000 steel wool, wipe and reapply. Makes a great finish; just need lots of patience. Every time I hear of tung oil, I think of Homer Formby.

 

[Wildman]

Lot of commercial Tung oil products products whether oil varnish blend or wiping varnish do not contain any Tung oil. Need a degree in chemistry to figure out whats in those products label with Tung Oil in the name. Forby's Tung oil very good example of a wiping varnish. Minwax Tung Oil, oil varnish blend.

https://www.popularwoodworking.com/techniques/finishing/oil-finishes-their-history-and-use/

In most cases these commercial product lot easier to use than pure Tung Oil.

Some pure Tung oil brands see directions for using straight and thinned!

https://www.dtep.com/hc02001.htm

https://www.realmilkpaint.com/shop/oils/pure-tung-chinawood/

Polymerized Tung oil brand which can be thinned with mineral spirits or their Di-Citrusol solvent, see directions.

Sutherland Welles, Ltd, Polymerized Tung Oil - Wood Finishing Products

Using pure Tung oil and getting the most protection and number of coat can range from 4 to 8 coats depending upon where you look for information. Drying and recoat times will also vary depending upon where you live.