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I’m trying to finish up an acoustic guitar. I have sprayed it with KTM-9, but have run out. I probably have enough coats, but I’m thinking a couple more coats wouldn’t hurt. I’m switching over to EM6000 from the KTM-9 on future builds and have a brand new quart of EM6000 ready to go. Properly scuffed with 400 grit and sprayed with denatured alcohol prior to spraying, would a final spray with EM6000 be advisable?

Thanks for any advice!

I am not so sure how it would adhere. If it could adhere I would not do just one final coat. .003" wet coat (recomended) * .24 (%solids) = .00072" dry coat. I am not sure you could sand and buff it with out going through that coat and getting witness lines. I have had some problems with Em6000 adhereing to zpoxy and now always use shellac in between without issues.

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http://www.Harvestmoonguitars.com

That's interesting since I've read that zpoxy and shellac aren't supposed to play well together. There's nothing like real life trial and error...

Zpoxy on shellac may have issues, shellac on zpoxy is fine. Basically pore fill on bare wood. Then it is OK to use shellac on a zpoxy fill. I have about 12 instruments pore filled with zpoxy, some french polished shellac and some with a stack of zpoxy, shellac and finished with EM6000.

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http://www.Harvestmoonguitars.com

Years ago, when I tried KTM-9, I believe that the current Target Coatings product at the time, the precursor to EM6000, was recommended to repair a KTM-9 finish. So, the EM6000 ought to stick. If it were one of mine, I would probably buy the extra can of KTM-9 rather than mix the finishes. The KTM-9 seems much harder than the EM6000 and while soft over hard can be safer than hard over soft, I wouldn't do it. They may respond differently to temperature changes over the years.

Here's the official response from Target Coatings:

Jeff Weiss wrote:

Yes, EM6000 will work well over the KTM-9. Clean the cured KTM-9 coats with water and denatured alcohol mixed 1:1, then fine sand with 600-grit aluminum oxide sandpaper. Proceed with EM6000 directly over the KTM. I recommend a minimum of two more coats of EM6000 to ensure that sanding scratches do not telegraph.

JW

I suspect the 'cured KTM-9' part is the key. That takes about two weeks. I would stick to KTM-9 for this one

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Joe Beaver
Maker of Sawdust