Varnish flaking off

Hi

I put the first coat of Schooner varnish on my hull last night. It went on smoothly and I was pleased since this was the first time I have ever varnished anything.

24 hours later I wet sanded the finish, wiped it down with a wet paper towel, and then started cleaning the surface with lacquer thinner. It seemed to be going ok until I noticed several areas where the surface immediately started changing texture and then started flaking off. 

What happened and how do I fix this problem?

Thanks

John


6 replies:

« Previous Post       List of Posts       Next Post »

RE: Varnish flaking off

John,

Lacquer thinner dissolves varnish. Let it all harden up again, wet sand everything until all the loose bits come off and start over.

Next time use either a wet cloth (water only, no hydrocarbon solvents) or a tack rag to clean off the dust. If you do use a tack rag, keep in mind that anything the tack rag touches cannot be epoxied without extensive cleaning first.

Good luck,

Laszlo

 

RE: Varnish flaking off

Years ago I had varnished a wood piece and thought it wasn't glossy enough so decided to spray it with high gloss lacquer. The finish crackled and flaked, same as yours. You can't mix the two products.   

RE: Varnish flaking off

Thanks for the replies.

I can't recall where I got the advice to clean it with lacquer thinner after wet sanding, but that was obviously bad advice. After it happened I figured that was the problem but just needed to make sure and have a plan to fix it. Ill sand down the loose stuff and start over.

Thanks

 

John

RE: Varnish flaking off

Follow up question...so what about using denatured alcohol to clean a varnish surface that has been lightly sanded or scotchbrited (is that a word?)   

RE: Varnish flaking off

   >>>Lacquer thinner dissolves varnish

LARGE AMOUNTS of lacquer thinner will dissolve varnish.  A rag just dampened with lacquer thinner, as a wipe-down between coats, won't cause any trouble.  But if you really soak the surface with lacquer thinner, it can damage the varnish.

Denatured alcohol is much milder, and that's what we use these days between coats of varnish.

RE: Varnish flaking off

   For reference, I wet a rag with lacquer thinner and experienced the problem. I sanded the coat down and have applied two coats since with no problems.

I'm not using lacquer thinner between coats. I have sanded and wped it down with a wet towel, followed with a dry towel to remove any leftover slurry and dust. I finished it off with task cloth.

Thanks

John

« Previous Post     List of Posts     Next Post »


Please login or register to post a reply.