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Film over oil finish?

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I made a half dozen small pieces and accidentally got something on them prior to putting on the finish, in little patches. It could be tung oil or wipe on poly. I didn't notice immediately and by the time I saw it, I couldn't clean it off with either alcohol or mineral spirits. The surface is decorated in another area and I don't want to try sanding the stuff off.

Sorry if this is a dumb question, but I've always used oil OR film, and not both, so this hasn't come up before. If I put some walnut oil on it, can I put a film finish on top of that? Does the oil have to cure first? Could I use spray lacquer or just an oil based poly?

Thanks for your help. I'm glad you all are out there.
 
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If the stuff you got on it by mistake was tung oil (You don't say what kind - pure tung oil, or is it some branded stuff such as formby's?) or wipe on poly you should have no problems using an oil based poly varnish for a film finish. Formby's (and Miniwax) tung oil is actually a version of wipe-on poly, it actually has very little actual tung oil in it. I use lacquer (Deft brand) regularly and it goes on nicely over pretty much everything I have tried it on, as long as it was dry (not sticky or waxy it won't stick to, for example, beeswax or paste wax finishes) in fact I think (I don't recall for sure) I used it on some pieces that actually had gotten a little linseed oil spilled on them, though I did wipe it down with mineral spirits trying to get the oil out, and then sanded to blend the grain coloring a bit...
 
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I do that all the time with danish oil to pop the grain then spray oil based poly over it. That said i did a couple test pieces with the light coat of dainish oil followed by spraying EM6000 waterborn lacquer and it had no problems sticking without orange peeling. With this test i am done with spraying oil based stuff. Less smell and easier cleanups.
 
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I routinely use Danish Oil on just about everything I make and follow up with Wipe on Poly or a Polyurethane oil based varnish, never had a problem, getting the oil dry is the key.
 

Randy Anderson

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I know an old post but seems on topic for me. I recently starting spraying a very light coat of thinned lacquer to my vases and hollow forms to give them a bit more shine without a thick plastic coat look. Walnut oil has been my go to finish for years and I like the look it gives. I've recently started having some of my pieces that had walnut oil on them get tacky to the touch long after they're done. Not right away, days or weeks later. Right after the lacquer spray I let it dry then lightly buff it with a spinning cloth on my lathe and all seems fine. Dry, nice shine, etc. I've checked days later and all well then I'll get one out of my cabinet and it feels tacky, a bit sticky, etc. Not right. I know nothing about lacquer and very new to using it. I thin it to almost 50/50 and use an air brush to get just a very fine coat. The pieces I sprayed had a walnut oil coat that had been on for quite some time so hard to believe it wasn't cured enough. Could the heavily thinned lacquer be impacting the underlying oil finish? Just seems strange that it would seem all good for an extended period of time then not. Can humidity, post application, impact lacquer?

I've seen other comments here re folks putting lacquer over oil, danish oil, etc so I know it can work...I'm just doing something wrong.
 

Randy Anderson

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Not sure I follow. Are you saying clean them with lacquer thinner before I apply lacquer? For the ones that get tacky I take lacquer thinner and scrub the finish off, do a little sanding with 400 then go back with a little oil and they're back to the pre-lacquer state. I want to figure out what's causing my issue before I do any more.
 
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Would be preferable to use a thin coat of shellac before using lacquer. I have seen some say they used lacquer over oil but all I have read says not to do that as it is not compatible. The shellac is a universal seal and will go onto anything and anything will adhere to it.
 
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I suspect there is a chemical interaction occurring with the lacquer but can’t explain exactly why. Probably the oils are dissolving the lacquer but it only happens slowly because the oils aren’t a “good” solvent for lacquer. That would make it occur slowly over long periods of time
 
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My best guess is the oil is not completely cured throughout the surface, and interacts with the lacquer. I use Mahoney's walnut oil on utility pieces. I have done some drying time time testing with it. At room temp it can take 3 months for the stuff to cure (this is a drop of oil on a non porous surface). I use a lot of thinned poly applied like danish oil, and in the winter I use a heated cardboard box to speed curing. I tried the same test with the walnut oil and found it cured out in a couple of days. I'm guessing the temp was 100-110F, but did not measure it. I'd recommend you heat them up for a couple of days to fully cure the oil throughout the wood.

Another option vs the lacquer is buffing and wax to get the desired sheen level.
 

Randy Anderson

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Thanks for info. I use Mahoney's or the Dr. Woodshop (with and without wax) on all my work. I've never really tried to measure dry/cure time. Once I don't get an oil film or sheen on my fingers and it doesn't leave an oil ring on a piece of paper I set in on overnight I consider it cured enough to sell or use. That time can really vary based on wood, temp, humidity, sunlight, etc. Fully cured throughout? No but well enough to put on a shelf for display. My style for all my pieces is natural, looks handmade, looks and feels like wood, not plastic, smooth but can tell from the feel it's wood, utility bowls can be used, etc. Not moving away from that which is why walnut oil is my go to finish choice. Plus it's so darned easy to use. My only motive for using lacquer was to give a bit more sheen to vases and hollow forms. At this point I'm going to stick to oil with wax and some buffing and move on. The risk of having the finish on a piece "go bad" after I sell it is too high.
 
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Thanks for info. I use Mahoney's or the Dr. Woodshop (with and without wax) on all my work. I've never really tried to measure dry/cure time. Once I don't get an oil film or sheen on my fingers and it doesn't leave an oil ring on a piece of paper I set in on overnight I consider it cured enough to sell or use. That time can really vary based on wood, temp, humidity, sunlight, etc. Fully cured throughout? No but well enough to put on a shelf for display. My style for all my pieces is natural, looks handmade, looks and feels like wood, not plastic, smooth but can tell from the feel it's wood, utility bowls can be used, etc. Not moving away from that which is why walnut oil is my go to finish choice. Plus it's so darned easy to use. My only motive for using lacquer was to give a bit more sheen to vases and hollow forms. At this point I'm going to stick to oil with wax and some buffing and move on. The risk of having the finish on a piece "go bad" after I sell it is too high.
Randy I use Polymerized Tung Oil, it is pure and is safe for food contact, it gets hard in less than a day, and gives a higher shine than other oil finishes, still not a plastic looking coat, easily done with a wipe on and wipe off in 10-15 minutes, an extra coat in a day or two.

Walnut oil takes a long long time to fully polymerize, and even after that it is still a fairly soft finish, with PTO there is no need for a wax coat over it, if you like a higher gloss, just polish it.

Yew bud vase.jpg
 
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