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Well, for various reasons, I've decided to refinish the body of my OLF SJ. It currently has eleven coats of KTM9 on, which I sprayed about three weeks ago. The surface is very rough, due to lack of familiarity with the settings of my new HVLP conversion gun, and I'm finding that I have to do so much sanding to get it smooth, that sand-throughs are pretty much unavoidable. I just went through the same thing with the GA, and it was a nightmare. Rather than relive that, I just want to either a.) Rough up the surface with 320, hit it with DA, then spray with (preferably) EM6000 or more KTM9; or b.) sand off all the finish and start from scratch with EM6000, as it seems to be much more forgiving than the KTM9.

Is there any reason why I shouldn't go right over the KTM9 with the Emtech? I know the jury's still out, and will be for a while, on their compatability over time, but what would you guys do?

Any help or opinions are appreciated.

Ken

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Mountain Song Guitars www.mountainsongguitars.com

If i started with KTM, and i still had enough to finish, i would finish with the KTM. Target finishes seem more popular right now, but KTM-9 is still a pretty great finish, and the difference between them is not huge. Eleven coats of KTM-9 should be plenty, but it sounds like something is not working out quite right, my advice is to address the issue with the spray gun/compressor setup. EM6000 may be more forgiving, but it would be better to not have to beg for forgiveness in the first place!

If you can't stand the idea of continuing with KTM, i would do some compatibility tests of EM6000 over KTM, and see how it turns out, i bet it would adhere just fine to a scuffed KTM surface, but that is just a total guess. At this point you could pretty much just flat sand the KTM coats you already have and spray a few EM6000 topcoats, and call it done, if they are compatible.

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Jordan Aceto
Ithaca, NY

Like Jordan, If I started with the KTM-9 I'd just finish it off, regardless of the leveling required.

My only though would be the burn in from the EM6000 to the KTM-9. Do some tests on scrap to see if they work together, otherwise you really shouldn't rely on someone else's"opinion" if it should work or not.

Don't rush it, you're almost there. The tendency is to "get it done" but that can lead to frustration as well as disappointment with the finish

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"There's really no wrong way, as long as the results are what's desired." Charles Fox

"We have to constantly remind ourselves what we're doing....No Luthier is putting a man on the moon!" Harry Fleishman

"Generosity is always different in the eye of the person who didn't receive anything, but who wanted some." Waddy Thomson

Great advice, Jordan and Rod. Of course you're right. I do have plenty of KTM, so I'll not tempt fate, and just go with it. One question -- I think part of the problem with the KTM was that it seemed rather viscous, and I wonder if that was why it wasn't laying down like I wanted. I spent lots of time on here and other sites researching gun settings, and despite lots of experimenting, I could never get the KTM9 to level out without putting it on so heavy that it ran like a scalded dog.

From memory, my air pressure at the gun ranged from 20 to 30 psi, my flow control was between wide open and one turn shy of open, and my spreader valve was generally wide open. I varied my distance from 8 to 6 inches away from the surface. The only variable I couldn't find recommendations on is the rate at which the gun moves across the surface. I tried a range from about a second to go from one side of the lower bout to the other, to about four seconds, which caused major runs.

I realize it's very difficult to recommend specific settings, due to variations in temp, humidity, and viscosity, so I'll just keep experimenting. Oh, also, I found that if I moved slow enough that it deposited enough material on the surface to self level, it would be very milky. My understanding is that each coat should not be heavy enough to cause milkiness. Is this right? I remember seeing Michael Payne's recommended viscosity somewhere, so I'll get a viscosity cup and start there.

Any other suggestions?

Ken

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Mountain Song Guitars www.mountainsongguitars.com

I generally start with the fluid valve turn almost all the way in and just turn it out till you get the gun spraying right.

Set the air pressure to the recommended setting on the gun, that way know know it's right for your gun.

The only other thing is making sure you have the right tip size for the viscosity of the material. Oh, and clean the gun good if you haven't done so in a while.

Check and see if you're local library has a copy of this book, and get it. It dis spells allot of mystery.

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My Facebook Guitar Page

"There's really no wrong way, as long as the results are what's desired." Charles Fox

"We have to constantly remind ourselves what we're doing....No Luthier is putting a man on the moon!" Harry Fleishman

"Generosity is always different in the eye of the person who didn't receive anything, but who wanted some." Waddy Thomson

So - first caveat is that I'm the least knowledgeable of all of those having responded.

I've finished four guitars with KTM9 and have had some challenges. Where I've arrived (and suggestions from others on how to improve technique are welcome) is that I spray the KTM on in steady parallel lines, laying it on well shy of anything that will run. (using an HVLP gun - 40 lbs.) The finish ends up looking like very fine orang peel after each coat, and doesn't actually really look wet, but I've found that it dries very quickly this way, and by laying down successive coats, there's sufficient thickness to level using the 400, 800, 1200, 2000 wetsanding method, with a little dish detergent in the solution. At the end of the day there are over a dozen coats on the guitar - Takes a while to cut down past the last "sparkle" - caused by the orange peel depressions, but ultimately, after buffing, it shines like glass. I haven't sanded through yet, although I don't think there's an excessive level of finish on here (judging from the microscopic "ledge" when I remove the tape on the bridge position.

This may not be textbook, but it has worked, to provide a decent finish. Comments? Reactions?

Corky --

Thanks for your input -- very helpful info. Sounds quite a bit like my "method", but maybe a few more coats, which I think is the difference. I stopped at eleven, and I suspect they were a little on the thin side. Ultimately, my problem was that the orange peel was significant enough that I lost most of my thickness in sanding it down level. That said, I have decided to go ahead and try sanding and buffing it out, then assessing it. Actually, the neck buffed out really nicely, and the back and sides look good, with the exception of one significant sand through on the back, and a few small places on the edges. I think they're worth repairing, and I managed to come up with a pretty good method from my last build, and that's another story...

Well, I'm off to the mistakes thread!

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Mountain Song Guitars www.mountainsongguitars.com