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DIW remains tacky after tung oil application

DLJeffs

DLJeffs

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I'm working on a box to house the controllers for the speakers out on our deck. The box is made from 3/8" baltic birch, with DIW thin sides and a birdseye walnut top. I've got 4 coats of tung oil on it now and the DIW sides seem to remain slightly tacky. The walnut is finishing up beautifully, no tack, etc. Does DIW have an oil base that causes tung oil to not cure fully? Maybe I just need to let it dry longer? I'm sure the DIW thins are fully dry - got them from John Teague here in WB a month or two ago. The birdseye walnut came from Eric R I think, I have three or four thin sheets of it with little dark birds eyes scattered about. Anyway, any thoughts about finish on the DIW?
 
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  • #3
Nailed it!!! I put it out on the deck in the sun and it's drying nicely now. The side exposed to the sun is well dried, so turned the other side into the sun now. Should be good to finish later this afternoon. Thanks Frank.
 
Pure tung oil, or the stuff marketed as tung oil?
 
Would love to see pictures of the finished project when you are done.
 
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SENC said:
Pure tung oil, or the stuff marketed as tung oil?
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The latter I guess ... Formby's tung oil, low gloss. I like it for indoor projects where moisture and durability isn't a concern.
 
I think that is actually a wiping varnish. If still tacky a very light wipe with a lint-free cloth moistened with mineral spirits and then drying in front of a fan or in the sun should remove the tackiness.
 
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  • #8
SENC said:
I think that is actually a wiping varnish. If still tacky a very light wipe with a lint-free cloth moistened with mineral spirits and then drying in front of a fan or in the sun should remove the tackiness.
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Good to know. I'll have to read the fine print on the container. The box did cure when I put it in the direct sunlight. Still ... why just on the DIW? The walnut cured perfectly. Other woods on other projects cured without problem. There seems to be something unique about DIW. I'm positive these thins are dry and not coated with wax or anything.

Update: did a little searching and found this nice, concise article summarizing what you're saying.
Popular Woodworking article on finishes

Makes me think the DIW is hard and non-porous enough to not let the "tung oil" soak in and dry properly.
 
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DLJeffs said:
Good to know. I'll have to read the fine print on the container. The box did cure when I put it in the direct sunlight. Still ... why just on the DIW? The walnut cured perfectly. Other woods on other projects cured without problem. There seems to be something unique about DIW. I'm positive these thins are dry and not coated with wax or anything.

Update: did a little searching and found this nice, concise article summarizing what you're saying.
Popular Woodworking article on finishes

Makes me think the DIW is hard and non-porous enough to not let the "tung oil" soak in and dry properly.
Click to expand...
I do suspect it's density is a contributor, but wiping varnishes (as I recall) generally don't "soak in" like an oil. I think this is more of a surface finish. I suspect a more porous wood like walnut allows whatever thinner is in the formbys to flash off both to the air and through the wood, whereas the DIW requires a longer period, moving air, and or a wipe with the same thinner to ensure the varnish isn't trying to setup over the thinner. If I'm right, thick coats may also contribute.

I've been a fan of pure tung oil for my calls - but it takes a little work and a lot of patience (generally need 24-36 hours between coats and multiple coats to get a nice, rich, deep finish). It will stay tacky on an oily wood if the bare wood isn't wiped with a citrus solvent, acetone, or the like to pull the surface oils out before the first coat.
 
DLJeffs said:
Good to know. I'll have to read the fine print on the container. The box did cure when I put it in the direct sunlight. Still ... why just on the DIW? The walnut cured perfectly. Other woods on other projects cured without problem. There seems to be something unique about DIW. I'm positive these thins are dry and not coated with wax or anything.

Update: did a little searching and found this nice, concise article summarizing what you're saying.
Popular Woodworking article on finishes

Makes me think the DIW is hard and non-porous enough to not let the "tung oil" soak in and dry properly.
Click to expand...
Watched a recent video that stressed that woodworkers should use 100% Tung Oil. ABW is a species that I wrestled with not drying after applying a finish! Chuck
 
Any oily wood (e.g. cocobolo) should get a base coat or two of DEWAXED shellac. THEN you can apply whatever finish you want and won't have problems.
 
DIW doesn't like oil finishes, like the rosewoods. It will cure eventually, but it takes a long time. However I have never used tru-oil, it doesn't seem to have a problem, I see lots of knife makers use it on DIW handles. Not sure what the difference is:ponder:
 
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phinds said:
Any oily wood (e.g. cocobolo) should get a base coat or two of DEWAXED shellac. THEN you can apply whatever finish you want and won't have problems.
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Paul - do those pre-coats of de-waxed shellac change the color of the wood? We applied shellac to the rosette area of my guitars prior to gluing in the rosette to prevent epoxy from leaching into the spruce. It darkens the spruce a little (makes it a tannish color) but when I sanded down the rosette all that stain color disappears, so it must be all surface effect.
 
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DLJeffs said:
Paul - do those pre-coats of de-waxed shellac change the color of the wood? We applied shellac to the rosette area of my guitars prior to gluing in the rosette to prevent epoxy from leaching into the spruce. It darkens the spruce a little (makes it a tannish color) but when I sanded down the rosette all that stain color disappears, so it must be all surface effect.
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Yes, like just about any finishing agent, shellac will cause the wood's color to darken/enrich. I really don't know how much shellac penetrates relative to other finishes but I've always assumed it was quite a bit.
 
I have used shellac on a few projects at work. We buy it labeled as a sanding sealer as I recall. De-waxed, ready to go. It wetted the surface slightly but based on how much coverage I got, I doubt it went very deep. On DIW, it won't go very deep anyway for the reasons previously stated.
 
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