Finishing Guitars with Tung Oil

Advice for a beginner on applying tung oil to a new guitar. December 31, 2005

I've been finishing a guitar I made with tung oil and it's coming out good so far, except for one problem. The top of the guitar is flamed maple, so I stained with a deep brown, sanded, then applied an amber. This gave the top a tiger eye look, and it's really wonderful.

I then started putting tung oil on it. I've been putting a layer of oil on every 48 hours or so. It looks wonderful, but the parts of the stain that are dark don't dry with the same gloss as the light parts. So when you view the guitar from an edge, you can see the amber parts of the grain as glossy as can be, but the dark parts are duller. I'd really like to get the whole thing evenly finished. Preferably more towards the glossy side than the dull. So... will the whole thing even out when it does the final four week drying? Or am I not putting enough oil on yet? I've been soaking the guitar for 15-20 minutes, then wiping the oil off vigorously, then 48 hours later I steel wool it, and do it again. So far I've put on about 7 coats. I'm using pure tung oil - not the stuff with varnish in it. Any ideas/suggestions?

Forum Responses
(Finishing Forum)
From contributor D:
It sounds to me like you simply need more coats. Try wiping off the excess oil less vigorously for a few coats. This will allow a faster build of the tung oil to achieve the sheen you're looking for on the less dense, more absorbent portions of the wood. You could also try dabbing a little extra oil on those areas. I have never had to put more than about 8 coats on some very dry antique furniture. I have also never applied tung oil to maple. When I use tung oil on furniture, I sometimes (rarely) apply the first 3-4 coats in the first 48 hours without steel wool in between coats. That is only when I know the wood is extremely dry. Ultimately, how I apply subsequent coats depends on how each previous coat is absorbed. Sometimes, a finishing method must be customized to the wood from step to step, meaning repetition of the same steps over and over may not be the most efficient method. Tung oil is my favorite natural finish, but it takes a lot of time and a lot of patience and a lot of rubbing.

From the original questioner:
Thank you. I did a little reading last night, and I realized that after I was done wiping, I'd let the guitar sit for two days and not even look at it. My guess is the finish kept seeping afterwards and by the time I checked, there were shiny spots and duller spots that seeped less. So last night I blew warm air over it and sure enough, it started seeping - a lot! So I wiped all of the seepage off, and today it looks evenly sheened. Even the chatoyance is back - it had begun looking bland and lackluster.

Should I keep applying oil, or am I done? Also, can you describe your procedure for getting a good shine (gloss) off of the wood afterwards? Do you sand with fine grade paper, then polish and wax, as I've been told, or do you just keep rubbing until it shines? How long do you wait to begin the polishing process?

From contributor M:

Are you cutting your tung oil with any solvents as a carrier? I buy my tung in bulk and was told by the seller to be sure to mix some mineral spirits or paint thinner into the tung to allow it to seep in the wood deeper before polymerizing. He told me it could take several days for tung to dry on its own if it is not cut with something, and especially if the humidity is high.

From the original questioner:
No, I didn't thin it. I figured I wasn't in much of a hurry, so I just took my time. I do have a humidity problem, though. I live right on the bay. So I just bought some damp rid to cut down the humidity in the drying room. Hoping that'll speed it up a bit.

From contributor J:
I have finished a few guitars with tung oil and have had the same problem with different woods. I don't think that it's related to any of the chemicals you used to finish as much as the grain direction of the wood at the points that finish roughly. If it's like a sunburst pattern, the stain would fall on the radiused or open-pore areas of the wood near the edges of the body. It looks all fuzzy because the open end grain pores are sucking the oil in at a much more rapid rate than the flat, smooth surfaces where it's nice and glossy. I sand these areas more finely than the rest of the guitar with 320 and then steel wools. I get it hot by sanding and it kind of smears all those pores closed. I still have to apply more oil at these areas. Some woods are much worse than others.

The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).

Comment from contributor I:
I believe I can help you with your problem. I have been refinishing wood for years and will use nothing but tung oil. Two things I would suggest. Number one is to thin your tung oil with mineral spirits. When starting with a piece that is stripped or completely bare wood, I start with a 50/50 blend. I use that for two or three coats and do not wipe it off. I apply it evenly. Make your mixture a little more tung oil and a little less mineral spirits as you go, but I would not recommend going to a mixture that is less than 25% mineral spirits. You'll find that it is much easier to work with and keep smooth.

The second thing I would recommend is to not use steel wool between applications. It sounds like you are digging out the tung oil with the steel wool because the steel wool is not completely flat. It will dig out the tung oil in places where the wood grain is softer or slightly indented. You need your abrasive between coats to be completely flat like a piece of very fine sand paper (600 to 1000 grit, wet sandpaper) on a rubber sanding block would be.

For extreme shine like I believe you are looking for, I usually wet sand. You must make sure you allow ample drying between coats but the results are amazing. I have a solid wild cherry buffet I refinished using this method with 16 coats of hand applied and wet sanded tung oil and the finish is like a $50,000 Steinway grand piano.

Comment from contributor C:
I've found when using any oil finish that the best way to get a truly amazing finish is that when you get to the last few coats of oil apply it by rubbing it in with fine wet and dry paper. Then go through the grits from 800 to 1500 sequentially and you will come up with a really lovely sheen. Another option is to use a thinner oil like boiled linseed or teak oil for the final coats. These dry quicker and once you have applied the last coats rubbed in with wet and dry paper (cleaning off the resulting slurry which contains microscopic bits of abrasive in between each grade) polish it up with a soft cloth. You could also seal it with a bees wax finish for even more depth and longevity.