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tung oil

6K views 17 replies 9 participants last post by  jeffswildwood 
#1 · (Edited by Moderator)
Just bought my first bottle of tung oil. I have read many of you use it but also have "special mixes". I tried a sample on some walnut and first coat look really nice. Right from the can. My question? Can it be mixed with polyurethane and what would be the advantage, if any. Can I use something like acetone as a mixer for either the tung and/or the polyurethane as a mixing, thinning agent. Maby just with the poly to make a wipe on. Or just leave the tung oil alone and just use it. Very basic questions but inquiring minds want to know.
 
#2 ·
A little goes a long way.
Raw tung oil takes a week+ to cure.
May be thinned with mineral spirits or naphtha.
Wipe it on and wipe it all off.
No advantage to mixing with poly; it'll just reduce the percentage of urethane, the most important component.
 
#5 ·
Formby's tung oil really isn't "tung oil"....it's just a very thin varnish, AKA wiping varnish. So adding more varnish to it (guessing that's what you mean by "polyurethane") won't do anything but make it build a little quicker. If you look at the MSDS, it shows Formby's to be almost 78% mineral spirits….so I certainly wouldn't add more thinner. Consider making your own by thinning any varnish by about 50%, and try it. In the meantime if you like the look of the Formby's, by all means use it. It won't have a very thick film, so in areas subject to high wear you might want to add a coat or two of brushed varnish.
 
#6 ·
Thanks guys, I've used polyurethane for years with good results but it always seemed "thick". I was looking for something to bring out the natural beauty of the wood and retain the smoothness without a yellowing. Looks nice on walnut but with poplar I do see a color change, didn't stay white. Suggestions?
 
#7 ·
I am the type that likes the natural look of any wood and so I typically use pure tong oil or linseed oil on cedar and oak, cherry, etc. Here in Phoenix with everything so dry I do a 50/50 mix with low-odor mineral spirits and wipe it on with a foam brush or cloth. I let it soak in a good 30 minutes and gently wipe off. You really don't want any to stand too long or it will get sticky and become a problem coating. I do this at least three to four times depending on the wood with 24 hours between coats. After that I may or may not put on a urethane sealer depending on where it is going and what it is used for. I find the pour oil is too thick and you end up wipe most of it off if you don't thin it. Tong oil is a favorite of mine if you haven't guessed.
 
#9 · (Edited by Moderator)
Varnish is a compound of a drying oil and resin cooked together. Most of them use linseed oil, and that is a big contributor to the yellowing you see. It's my opinion that the urethane resins also lend a "plastic' look I don't like. There is another varnish that doesn't have the plastic look or the linseed oil: P&L 38. It's hard to find, but if you can locate it (we don't have any Pratt and Lambert stores around me) it's formulated with soya oil and alkyd resins. It's still has a slight amber cast but hugely less than the linseed oil formulas, and it doesn't change nearly as much over time. Other options would be shellac (shellac is colorfast, no change at all) or a clear waterborne. Waterbornes can be water clear, which to many is the same problem in the opposite direction. there is also a varnish made with tung oil and phenolic resins (Waterlox original), and it's the darkest of the varnishes out of the can, AFAIk.
 
#10 ·
I'm on coat three with the formbys and so far I like what I see. I feel the wood but have a nice grain enhancement. I used urethane for years and want to expand my finishing. Finding out the formbys is primary shellac was disheartening but shellac was one of the finishes I wanted to try so not so bad after all. I will try to find P and L 38 (maby amazon) and try it soon. Thanks all for the tips!
 
#12 ·
I used urethane for years and want to expand my finishing. Finding out the formbys is primary shellac was disheartening but shellac was one of the finishes I wanted to try so not so bad after all.
- jeffswildwood
Something was lost in translation….there is no shellac in Formby's, only varnish and thinner.
 
#13 ·
Formby s tung oil really isn t "tung oil"....it s just a very thin varnish, AKA wiping varnish. So adding more varnish to it (guessing that s what you mean by "polyurethane") won t do anything but make it build a little quicker. If you look at the MSDS, it shows Formby s to be almost 78% mineral spirits….so I certainly wouldn t add more thinner. Consider making your own by thinning any varnish by about 50%, and try it. In the meantime if you like the look of the Formby s, by all means use it. It won t have a very thick film, so in areas subject to high wear you might want to add a coat or two of brushed varnish.

- Fred Hargis
Actually, it's "Formby's Tung Oil Finish." It's a tung oil/alkyd varnish diluted to a wiping varnish consistency. It shouldn't be called "tung oil."
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#14 ·
I've got some of the same stuff. Sent my wife to the store said "see if you can find some tung oil". She came back with the formby's. I've used it on one small project and it was ok.

since then I bought a quart of "Hope brand" pure tung oil from Amazon. Havent used it yet.

-Paul
 
#15 · (Edited by Moderator)
I'm guessing that formbys is pretty much a wipe on polyurethane? Maby I'm confused, is varnish actually polyurethane? I like the look but I always likeed poly anyways. Now to find some actual tung oil. maby even some boiled linseed oil. I will be coating some 14 year old walnut so I want a great natural look.

Fred, sorry I was mixed up with shellac and varnish, my confusion…
 
#16 ·
I use 100% pure tung oil from Woodcraft, at about $20 per quart. A little goes a very long way and it oxidizes in the bottle, so squeeze the bottle or add marbles before closing to keep oxygen out. One quart lasts me over one year of building small furniture, wall and mantle clocks, music boxes, etc. It is beautiful with walnut or cherry, and gives a nice flat finish with hard maple.

It is rather thick, so I usually dilute it 50/50 with mineral spirits. I rub it onto a smoothly sanded surface (minimum 220) with a wad of XXXX steel wool. Dull spots need more oil, as it has all been absorbed by the wood.

After about 20 to 30 minutes, it will start getting sticky. Wipe it all off with a polishing action with soft, absorbent cotton rags. If it is getting too sticky, quickly rub over the oil with more mineral spirits to slow curing.

It will be dry to touch in an hour or two, won't collect dust, but has not yet cured. Add more coats at about one day intervals until you like the finish. The finish will be deep but flat. When I prefer a little gloss, I mix about equal parts tung oil, oil based urethane, and mineral spirits for the final coat or so.

The resulting finish is easy, beautiful, and durable, but won't be fully cured for about a month. It can be handled when dry to the touch, but might stain a carpet or table cloth until fully cured. If any "sweating" should occur while it is curing, just polish it off with a clean rag. The finish is durable, and easily rejuvenated if ever needed by doing one more pass with tung oil and mineral spirits. Do not use household furniture polishes, as they may make the finish turn milky over time.
 
#17 · (Edited by Moderator)
I m guessing that formbys is pretty much a wipe on polyurethane?

Fred, sorry I was mixed up with shellac and varnish, my confusion…

- jeffswildwood
It's not a wipe on "polyurethane". In the world of confusing finish terminology, many woodworker's refer to urethane varnish as "polyurethane", or "poly" (thanks to Norm, maybe). But other finishes also have some urethane resins in them as well, like some waterbornes. The better varnishes (again, IMHO) are made with alkyd resins, or phenolic resins….but they are varnish just like "poly". What's better about them (once more: IMO) is that they don't have the plastic look, they also have no adhering problems (caused by urethane resins) so no scuff sanding between coats for adhesion is needed. So, calling a finish "polyurethane" can mean different things to different folks, though I usually guess they refer to varnish. Formby's isn't a "wipe on polyurethane", but rather a wipe on "alkyd" varnish, in that regard it's very good….but it's still almost 80% MS. I highly recommend you get Flexner's book "Understanding Wood Finishing". Some really good basics in there, and the book reads very easily. You might also want to check this article by Bob on these specific types of finishes for some more basics. Notice the placement of Formby's with the thinned varnish group.
 
#18 ·
Thanks Tiger and Fred for the tips and info. This stuff is confusing. I have really made improvements in my woodworking in the last few years but no growth in my finishing. To me this is a critical step in any project. Knowing what to use and on what project. Really enjoyed the article and have to add the book to my list of need to buy's. Thanks,
 
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