MIMF

Hi folks

I'm finishing a guitar top with lacquer for the first time, but I just screw it up while gluing the bridge.
I usually glue down my bridges on a white top, but this time I decided to change, thinking that lacquer is harder that shellac.
I don't know what I was thinking, but I heated a bit the top, and the tape glue melted into the finish.

Should I sand back until the raw wood or spray some more lacquer? The top is already wery thin and is WRcedar in a classical guitar that sound really good.

Thanks


Manel

The adhesive simply softened the lacquer; leave it alone for about a week or two, and it should harden back to its previous state, and you can then level the area and buff it back out.

It depends on how bad it is, but you should be able to get away with wetsanding a bit and if it doesn't buff out ok after that then another coat of lacquer will probably take care of it.

Mario, You are probably thinking on average thickness, but mine is super thin because I was afraid to choke the guitar. (it's a lattice braced classical guitar)
My plan was spray more if necessary after trying the guitar.

So my hesitation now is sand the whole top or spray more after a light sanding.


Mark. I think is pretty bad, it was hard to take off the tape in some areas.

So I guess I have to sand the area, add another coat. Then buff and polish.

Thanks to both.


Manel

Watch out for the blue 3M masking tape. The adhesive will destroy lacquer even without heat. The green tape is usually safe for lacquer.

Yes, It was blue tape, and the heat was minimal, it barely heated anything.

Thanks Bob.

To avoid sanding you can remove all the lacquer from the top using lacquer thinner and steel wool. The steel wool is not absolutely necessary, and I have used paper towels instead. If the back and sides are lacquered be careful not to let the thinner drip on to the sides.
If a light sanding will remove the tape residue without going through the lacquer to the wood, I would do that , then spray a light coat of lacquer on top.

Thanks Clay to give me more options.

Here's a picture of the problem.

You might be able to scrape the residue off with a single edge razor blade (with the ends rounded over so they don't dig in) then a light respray of lacquer to smooth things out.

I'd try a little mineral oil rub or perhaps http://www.goofoffstainremover.com/adhesive-residue first.

See, I don't think this is adhesive residue. I had a new lacquer finish damaged with the blue masking tape also. The tape melts into the lacquer and leaves an inprint but no residue. I was able to do a little wet sanding and buff it out relatively easily, but then again, my damage did not look as bad as the photo above.

Does using the green masking tape alleviate the problem?

The blue tape is supposed to be both low-tac and more resistant to drying out over time (I think you get a week or two instead of a few days).

I don't understand the chemistry but 3M explicitly warns that the blue tape will harm lacquer finishes (it's okay with waterborne lacquer). It claims the blue tape adhesive is natural rubber. It advertises the green tape as having a proprietary solvent free adhesive. I keep a large supply of the green tape (2060) because I use it for holding bindings while the glue dries. When I need to mask something on a guitar finished with nitro, I finger the green tape to remove some of the stick and use that. I use the blue for masking on my guitars which are finished with waterborne. The 3M green (2060 and 233) is okay for lacquer. I wouldn't bet on any color code in other brands.