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Lacquer over sanding sealer

10370 Views 17 Replies 9 Participants Last post by  TBFGhost
Ok so I'm not a painter but I have painted. I'm a carpenter by trade. The painter on our job is using lacquer as finish on our cabinets,but it just keeps flaking off mostly in the inside corners. He wash coated the cabinets with sanding sealer(wood pride) regular oil based. I told him it was the sanding sealer making the lacquer flake. I don't know much but oil based under lacquer???? Any thoughts
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You can get decent adhesion to urethanes with lacquer, but that isn't a urethane from what I saw at the Glidden site. It says it's a gloss product using zinc stearate - zinc stearate can cause adhesion problems. To have any hope of good adhesion, all parts of the surface have to be roughed up.

I don't know about the specific sealer compatibility - the TDS says something about vinyl and solvent - I've never worked with vinyl as a sanding sealer.

If you do a tape test (Rub scotch tape down onto the finish, pull it back off - some people will use duct tape instead) on the flat part of the cabinet and the lacquer stays stuck, it may just be inadequate sanding in the corners.
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Ok i put blue masking tape on the flat surface and the finish pealed off the hole thing. Does anyone have any suggestions on how to get the finish to adhere.
True sanding sealers must be matched to the top coat. Lacquer based sanding sealers contain stearates which inhibit adhesion of oil and waterbourne finishes. Lacquer based sanding sealers should only be used under lacquer finishes. If I can remember right, we a used Sherman Williams brand a few years back when I worked in a cabinet shop. The results were beautiful and never any flaking. See what exactly your painter used. Sounds very much like a re-do job on his part I'm sorry to say.
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Blue masking tape = really no adhesion. The first step is probably strip off the lacquer and see what you can get to stick. Take a look at the sanding sealer manufacturer's site and see what of it's finishes this is compatible with. You're going to have to do a few tests to see what works.

Painter's tape isn't an adequate adhesion test - use the clear Scotch tape. Duct tape can be a more severe test, but I only use that for exterior painting.

Like I said, I haven't worked with that particular product, so I don't know where the incompatibility comes in. With the old formulations, you could spray lacquer over urethane, but I don't know if you can put urethane over vinyl, or whatever it is.
I agree with Reg. There are lacquer sanding sealers (made by manufacturers like Gemini, Amteco, and others), which are compatible with lacquer topcoats. Keep in mind that the solvent in a lacquer topcoat (lacquer thinner ) is much hotter than a mineral spirits-based alkyd sealer.
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Why didnt he just use shellac? Easy to use and all clears bond to it.
As far as I can tell he's an idiot
Laquer thinner to remove failing laquer. A coat of shellac or vinyl sealer & recoat with laquer.
Ok i put blue masking tape on the flat surface and the finish pealed off the hole thing. Does anyone have any suggestions on how to get the finish to adhere.
Jsmith185, who are you referring to?
Actually de-waxed shellac all finishes should bond to. Regular Amber or Blonde shellac are not good under polyurethanes, possibly including WB polys but I can't remember for sure. I just know they can be an issue. Best to read the label.

Seal-Coat is a great all purpose clear shellac for using over or under most finishes.
Metro M & L said:
Why didnt he just use shellac? Easy to use and all clears bond to it.
These work fine under oil based polyurethane.
Regular Amber or Blonde shellac are not good under polyurethanes
I was talking about the painter on our job not anyone on here
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It's a steep learning curve when trying to find a sealer that all will adhere to. I've recently left the solvent based lacquers in favor of the water borne variety. De waxed shellac is an excellent interior sealer or transition coating. Mixing your own shellac is an option but for me it doesn't make financial or time line sense, I use Seal Coat and find it to be an excellent product. I think Reg nailed it, you're options are either stripping the the existing finish off or simply starting with new doors. Good luck.
Thanks, after doing a little more research it looks like while many experts and the back of the Zinsser can says not to use under poly, many woodworkers claim to have used it, especially as a sealer coat, under poly with no problems.
hdavis said:
These work fine under oil based polyurethane.
I've used it this way since the late 60s / early 70s. I haven't used it since the urethane reformulations, but I wouldn't expect an issue. I've never tried water borne finishes over shellac because shellac will absorb water.
Thanks, after doing a little more research it looks like while many experts and the back of the Zinsser can says not to use under poly, many woodworkers claim to have used it, especially as a sealer coat, under poly with no problems.
I know a couple floor finishers who use the shellac as a sealer so they can seal and recoat with oil poly or water poly in one day. I have done both of these and never had any issues other than the shellac being so hot its difficult not to get lap lines.

I was talking to one old dog and he pointed out you should work in really narrow columns. Talk about a simple solution you're embarassed you didnt figure out yourself.
Thanks, after doing a little more research it looks like while many experts and the back of the Zinsser can says not to use under poly, many woodworkers claim to have used it, especially as a sealer coat, under poly with no problems.
It is the wax in shellac that can cause adhesion problems. I used dewaxed shellac, zinsser seal coat, a lot. I use it under oil poly, water poly, water laquer, solvent laquer....never a problem.

Zinsser makes three types of pre-dissolved shellac. One is Seal Coat. It is a two pound cut and is de-waxed...meaning the wax is removed. They also have blond shellac in a three pound cut and Amber shellac in in a three pound cut. The latter two contain wax.

A two pound cut means two pounds of flakes are dissolved in one of gallon of alcohol. Three pound cut means three pounds to a gallon.

Target Coatings makes a water born shellac I am thinking about trying...

http://www.targetcoatings.com/produ...rain-fillers/ultraseal-wb-shellac-sealer.html
Actually de-waxed shellac all finishes should bond to. Regular Amber or Blonde shellac are not good under polyurethanes, possibly including WB polys but I can't remember for sure. I just know they can be an issue. Best to read the label.

Seal-Coat is a great all purpose clear shellac for using over or under most finishes.
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