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Applying Lacquer over Oil Based Varnish?? or Visa Versa?

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Forum topic by treefrogdog posted 1059 days ago 5522 views 0 times favorited 4 replies Add to Favorites Watch
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treefrogdog

29 posts in 1208 days


1059 days ago

Topic tags/keywords: question

Need some advise. Recently decided that Deft Lacquer is a fantastic product. I do sculptures in wood and rock. I have recently taken off most of my previous oil based finish on several rocks and wood sculptures because they were too “yellow” and “plastic” looking for me. Note the one piece I have posted here. I am now using the Deft product and its a huge improvement. Question: If I have some residue or even a few coats of the oil varnish, can I finish with lacquer? Or put on a lacquer base and finish with oil varnish? I have Bob Flexner’s book and kind find info on mixing and matching. Also…is some glue reactive with Lacquer as well? I know plastic is a bad idea around lacquer. Thanks!

-- Josh, Mesa Arizona http://www.facebook.com/profile.php?id=100000741453388


4 replies so far

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GaryL

1074 posts in 1433 days


#1 posted 1059 days ago

Try sealing it with shellac first.

-- Gary; Marysville, MI...Involve your children in your projects as much as possible, the return is priceless.

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CharlesNeil

1116 posts in 2473 days


#2 posted 1058 days ago

the issue is anything oil base doesnt like lacquer, the solvent in lacquer will “lift and curdle’ the oil base unless its really dry, as state above a light seal with shellac will help, but even then the shellac can lift it, one solution is to put a coat of water base finish, ( non reactive) then use the deft over that, also brushing lacquer which I think deft is in qts or gallons, now days, is much slower drying, ( for flow out in brushed applications) the spray cans are not , but in either case, the lacquer as well as shellac are reactive finishes, meaning one coat will soften the other, and lacquer will also soften and penetrate shellac, so the answer is a coat of a water base finish as a barrier coat, let it dry several days, and then use the lacquer over it, give it a light 320 scuff sand , and you should be fine, water base is non reactive and its chemical resistence is excellent, so the premis is, the WB seal’s the oil base procuct, ( i am assuming this oil base is totall dry , if not be sure to seal with shellac before the WB) , and doesnt allow the lacquer to penetrate and lift the oil base, if applying the shellac over the oil, just a very light coat and use a good dewaxed shellac, ( seal coat , spray can or mix your own), I know this sounds complicated, and more than you want,, but its how it works to be sure, not to say if this oil coating is really dry the lacquer will not go over it ok, if you used a chemical stripper and still have oil based residue thats another issue, hope all this makes sense, if not ask away

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treefrogdog

29 posts in 1208 days


#3 posted 1056 days ago

Charles. Thanks so much!! Not at all to much info. Really appreciate the detail.

Cessna. Yes. I think I am much better at applying varnish. At least that is what I tell myself…:)

-- Josh, Mesa Arizona http://www.facebook.com/profile.php?id=100000741453388

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bilbaggins

97 posts in 1052 days


#4 posted 1049 days ago

Hi treefrogdog!

I build guitars and have discovered that lacquers only “like” to be used over water based or turps based finishes.

I have also been told that two pot finishes (acrylic) with auto lacquers are the go.

Nitro-cellulose which is preferred by many instrument makers is far softer but blends beautifully coat-to-coat. I add turps based wood stain in small amounts to colour it successfully which is a bit odd as you need a lacquer solvent for cleanup etc. Might be flirting with danger there…

Deft is highly regarded so you’re on the right track there!

Lacquer takes up to 30 days (and more) to “harden” as it’s weather/humidity dependent. —CURING is a minimum of 28 days per coat, so ten coats = 280 days!!! True… my chemist friend told me~!

Trying to seal in an oil based finish can be almost impossible (so I’ve been told) and I can’t find any reliable info online for that one.
A ~chemist from a paint manufacturer I know said it is possible if you lay down a number of barrier coats as Charles (above) has stated.
Water or turps based acrylic can still allow oils to leach thru so for my own builds I would risk it but not on my customers guitars. Back to bare wood and start from scratch for those.

As far as glue is concerned again water based or activated is the safe route—I have used Titebond, many brands of cheap white wood glues and pot hide glues without any adverse issues; that I am aware of anyway!!!

Checked out yr work—very nice !

As a by-the-by—i used to do a lot of sheet copper work (murals) and used straight up auto lacquer directly onto the toned and polished metal very successfully for many years. No yellowing and a nice hard surface that can be cleaned and polished with ordinary consumer household brands. No abrasives of course. To get a real high sheen you can use any cut n polish type finishes eg: TurtleWax or Repo—there’s a million of them!

Hope this helps a bit—good luck

-- bilbaggins says: The best time to plant a tree is twenty years ago. The second best time is now. ~ Chinese proverb

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