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Ok on a repair I am doing I tested the finish with acetone it did not melt it at all, just dulled it. I tested with DA, it too just dulled it . So I am assuming that the finish is Polyester. What solvent should I use. Second question is if I sealed it with shellac could I coat over with nitro with out causing problems?MichaelP38467.7379282407

Michael,

Do you want to strip the guitar or just recoat it?
If you just want to recoat, then sand the existing finish and seal it with shellac. This should allow you do go over with nitro without adhesion problems. You could also use polyurethane as it coats any finish very well.
good luck

one more thing...make sure that your shellac is de-waxed if you decide to use it as a seal coat!!

Tanks Robbie

I am over coating. I figured I could seal coat and over coat with out issues. I use Zinner’s 100% wax free Seal Coat as my sealer.

My main problem is there are micro cracks in the finish that have dust and oxidation in them that with out melting the finish in those areas will appear under my new finish coat.

I don't want to remove the old finish because it is a tobacco burst and the dark pigment is in the finish and not stained onto the top.

This guitar had a major crack in two places that went un-repaired for 10 years. I am not sure I can get rid of the Whitish residue that is built up in the micro finish cracks with out melting the finish back some.

Got any Ideas?

Wow, that is a tough one Michael. One thing good about having a color in the finish is that they are easily repaired and disguised with toners. Here is my suggestion: If you are not able to remove the contamination frm the small cracked areas with compressed air then try a very small amount (very small) of lacquer thinner applied with a q-tip to try and redissolve the areas that have the dust or other contaminations. Test this in a small area first. You should be able to do this before getting into the toner coats.
If by chance you happen to get into the color layer you can easily disguise this using dyes or spray toners and then you can top coat again with a clear coat.
Let me know how it goes.   

I will try that tonight. Thanks again Robbie

I tried the lacquer thinner last night and it does not dent this finish, just dullls it. I hate to say it but I might have to sand it down in these areas to get the contamination out. Im out of any other ideas.

violin folks use deionized water to remove crude from cracks. more on this on mimf. i have also used hydrogen peroxide, but i don't know how that would go with your colour coats.

I have had good luck with Naptha and Mineral Sprits but especially Naptha followed by diluted dishwashing soap. Also with a product named Howard's Restore-a-Finish, which actually comes in colors. But you really have to test these with very small spots. But may be worth trying, if you are on the verge of having to strip anyway.

Check out this link and see if it helps at all.

http://www.assoc-restorers.com/r-articles/saving_the_finish. html

I just got an email from Frank Ford and he informs me there is no commonly available solvent that will dissolve Ovations finish. I forgot to ask him what it was but he told me that it was a catalyzed finish, and all I could do is to fill dents and cracks best I could with CA. I hate to sand out as deep as would be needed to get the contamination in the cracks out…..WELLLL POOO

ya.... yo.....you....you're....... you're working on a what??????!!!!!!!!

solution:

   1) find little person, gnome, leprechaun, etc., and
   2) find small paddle, and
   3) give that object and the paddle to little person.

s/he now has a kayak!!!!crazymanmichael38469.8757407407

It is still that Balladeer that had the ten year old top crack. all I got to do now is refret job and they wanted a fresh top coat of lacquer but I am not going to provide that if I cant get rid of the contamination that has gotten in under the the cracks over the past ten years. I'm going to fill the cracks best I can and buff out the finish and call that good.

Well I should have done this in the first place but I didn't. I called Ovation. The finish is catalyzed polymer. Kind of like a very hard epoxy. No commercial solvent is available. So I will fill the crack lines with CA, level, polish and buff. That is the best I can do unless I remove the finish and refinish. I know the customer will not spring for that because that would drive the price over the book value of the guitar. After crack repair, custom inlay and refret he is at about half the book vale as is.

Michael, before you do that, You might try a behlens product called Quala-renew. Addam Stark told me of it and he said it pretty much has a solvent that will melt anything. I had a badly crazed top come back to me and I put some of that in a pipette and just ran it down the cracks. In about 10 minutes the cracks were gone. I mean GONE! Might be worth a try on this finish. I got some at Woodcraft.

Thanks Paul I will give it a try.

Bummer Michael.
You still have an advantage on this job...the color coat. Use some dyes or toners to hide the places after leveling them with CA. They will blend right in and you can then clear coat the thing and get it out the door.

[QUOTE=Robbie O'Brien] Bummer Michael.
You still have an advantage on this job...the color coat. Use some dyes or toners to hide the places after leveling them with CA. They will blend right in and you can then clear coat the thing and get it out the door. [/QUOTE]

But I am not going to be able to hide the whiteish contaminate in lighter areas of the sunburst. I though about taking my demel and router base and cutting down to the contamiate but after talking with the customer we are just going to leave it. He spent $100 for the inlay, $200 for refret and $150 for the cracks repair. He does not want to sink more into it.

You are right. Those can be problem areas. Lesson learned I guess.