Laquer/Varnish problem... did I screwed my guitar?

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Laquer/Varnish problem... did I screwed my guitar?

Postby De Ferre » Thu Dec 07, 2006 8:52 am

Gentlemen,

I'm building a telecaster (kind of) from parts I gathered. It sounds nice, but I did something wrong with the varnish...

I asked a local artist to paint the body and she did a nice job using acrylic paint. Later I had to search for a proper varnish. So, in a local artists' shop they gave me what they recomend for varnish on top of acrylic paintings: Archival Varnish Mineral Spirit Acrylic Aerosol.

I applied several layers and it looked ok, but... after several weeks it seems not to be totally dry. It gets worse with warm contact, sticky. And it even gets the colour of my pants after a playing session, due to friction. :cry:

My question is: can I apply another laquer on top of that one? Perhaps one of those laquers for car painting? Would it react badly or, on the contrary, it would get dry and hard? I'm miserably lost. :cry:

Thanks a lot in advance!!!
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Postby maxx england » Thu Dec 07, 2006 11:52 am

I'm not a paint expert, but it sounds to me like you will have to strip back to the wood or the base coat and start again with the correct grade of paint or lacquer. Sorry to bring you the bad news.
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hooo boy.....you got a problem.....

Postby WeirdOlAndrew » Thu Dec 07, 2006 7:34 pm

I used to do custom painting on motorcycles and guitars, so I know a bit about it. One thing most folks don't realize is that paint doesn't just "dry", there's what we call the flash dry, where the solvent dries out of the paint, then it works like a 2-part epoxy. The oxygen in the air reacts with the chemicals in the paint to harden it. So you need to shoot THIN layers, with plenty of time between layers for the air to react with the paint.

Usually, drying soft or sticky means that not enough air got to the paint (or varnish..whatever) for it to react properly. DON'T add anything on top of the mess you've already got, that'll just make it worse.

If it was me, I'd try MILD heat, like say from a spotlight a few feet away, to see if you can speed up the reaction. (It'll stil harden, but it might take 20 years under normal conditions, without some help.) Be really careful with this, it's easy to get too much heat, and blister or discolor the finish. You want it hot, but so you can still touch it. Check frequently for an hour or so, and then let it stay overnight. If its hardened, at least in the spot you were trying, you'reOK. If not, you'reprobably out of luck. Might try to contact the manufacturer of the 'varnish' and see if they have any help. There may be 'dryer' agent you can add.

For the M/C parts, we make a box, about the size of a refrigerator, lined with metal foil and a few sunlamps to cure the paint. I think its about 150 to 180 degrees F in the box, if that's a help.

If I was doing a guitar body, (starting from clean wood) I'd lay down a layer of clear shellac, and sand, repeat till smooth. Then a solvent base acrylic (automotive) laquer and base color. Then do my painted scene in artist's acrylics, then layers of clear, (usually DuPont) auto laquer over. This assumes a high quality spray gun and the skills and accessories to use it. I've done pretty good jobs with spray can laquers, (see House of Kolor products, Krylon, etc) its just harder to work with.

Note that most modern automotive laquers are a 2-part catalyzed system, and you don't want to try to work with those without lots of the right equipment. Among other things, the stuffs a cumulative poison and you NEED to wear full breathing gear and skin cover. A t-shirt and a little white dust mask doesn't cut it.

Ask for an old-fashioned alchohol based laquer, and always use a thinner from the same manufacturer as the paint, or a top brand like Bortzoil. Cheap thinners aren't pure and can do really weird things to your finish. I only use them for cleaning the gun.

Good luck and let us know how it works out....
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Postby ricochet » Fri Dec 08, 2006 12:51 am

Andrew, reckon an ultraviolet "sun lamp" would work? UV is a big generator of free radicals. I've thought about trying one when I put boiled linseed oil on too thick to dry well and got a sticky mess. That'll eventually cure, but it takes a year or more.
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Postby maxx england » Fri Dec 08, 2006 11:59 am

What about a fan heater? Plenty of air movement for evaporation, and heat to speed up any chemical reaction.

Another thing, I didn't know that acrylics over cellulose or the other way round, don't work. You can get an alcohol based barrier coat to stop interaction between them. Perhaps this would be something that should have been put in place before painting started?

Experts, your opinions, please.
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Postby De Ferre » Mon Dec 11, 2006 10:53 am

Thanks for your feedback!
I'll see what are the results I can get...
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