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Can polyurethane be applied over laquer

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Forum topic by woody57 posted 08-07-2011 10:21 PM 16274 views 0 times favorited 5 replies Add to Favorites Watch
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woody57

647 posts in 2887 days


08-07-2011 10:21 PM

Topic tags/keywords: finish

I must admit that even though I have many years experience in furniture and cabinet making that finishing is a weak point for me. I have been known to hire a professional to finish some of my projects.

I want to refinish some cabinets. I would like to lightly sand and apply a couple coats of poly with a brush. The current finish is laquer that was sprayed on. I won’t be able to use a spray gun because of the location. The reason I chose poly is for the durability. If anyone has another suggestion, I’m open.

My concern is will it adhere properly to the laquer?

-- Emmett, from Georgia


5 replies so far

View olddutchman's profile

olddutchman

187 posts in 3395 days


#1 posted 08-08-2011 12:13 AM

Always try to make changes on a piece not seen, or a scrap that has thr same finish over it. A lot depends on the finish before. If the paint was installed by a painter who used good guality paint, or came painted from the factory makes a big difference. Some of the laquers used todayby amatures are not a true laquer. I have had a laquer finish wrinkle when sprayed over. Laquer will normally take a another finish just fine. In order to get a good adhession, use a pre paint cleaner for laquer. It will soften the surface, and clean the finish for new coat of paint. Poly eurothane finishes are not very hot to finishes it’s applied to. The prepaint cleaner will also give You clues to how Your old finisg will hold up. Try that in a non seen place also. Apply it over the old finish and then watch it for reactions . If it doesnt keep the old finish soft, and dries up in ablot 3 minutes, It will work ok. I hope this gives you a good heads up as to what can do wrong!

-- Saved, and so grateful, consider who Created it ALL!!!

View bilbaggins's profile

bilbaggins

99 posts in 1909 days


#2 posted 09-14-2011 03:43 PM

Hi woody57—my sources tell me poly and lacquer repel / dont mix well!

I build guitars and you have to use one or the other. Either can be used with acrylics, water based finishes etc but not with each other.

If you find out different … please post it here!

rgds

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

View miles125's profile

miles125

2180 posts in 3465 days


#3 posted 09-14-2011 04:02 PM

My experience is that you can put anything on top of lacquer. But not so the other way around.

-- "The way to make a small fortune in woodworking- start with a large one"

View Carbide's profile

Carbide

210 posts in 1906 days


#4 posted 09-18-2011 06:20 AM

Actually I have called Minwax with the same question. They said absolutely not. They said that Laquer is meant to soak into the wood and Poly is meant to sit on top of the wood. They told me that the two would not be compatible and would possibly not dry and cure right. I have run into finish compatabilities in the past and ended up stripping a freshly built set of walnut cabinets to start over. The problem actually emerged about a week after the finish had cured. Not a good idea to experiment on a finished project.

-- When it feels like a job, it isn't a hobby anymore.

View David Grimes's profile

David Grimes

2078 posts in 2099 days


#5 posted 09-18-2011 07:22 AM

Alkyd varnish over ordinary lacquer. Urethane will adhere, but not for the long haul. If you use catalyzed lacquer (pre-cat or post-cat), the durability is built-in and no need to put any protective coat over it.

-- If you're going to stir the pot, think BIG spoon or SMALL boat paddle. David Grimes, Georgia

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