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I've been using KTM 9 now on most of my 8 guitars and have gotten accustomed to its peculiarities and foibles. Now, supply issues are causing me to consider alternatives. Here are my criteria:

I don't want to use nitro, because my spray setup isn't spark proof. If I'm spraying, I want to spray water-based.
I like the glossy, buffed look that nitro (and KTM 9) can provide when done properly.
I've got an HVLP setup, with sufficient pressure, and a respirator, which is sufficient for a "lower-toxicity" finish. Yeah, I know, none of these finishes are really non-toxic.
I'm finishing steel string guitars, so looking for a harder finish.

What do you all suggest?

Corky, call the folks at Grafted Coatings and order up a gallon of KTM-SV and give that a try. It's MUCH better than the KTM-9 product for what we're doing. It's still a waterborne, but without a lot of the issues that the 9 has.
If you want, email Rolfe Gerhardt over at Pheonix Mandolins and see what he thinks. He'll be glad to tell you all about it.

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"I want to know what kind of pickups Vince Gill uses in his Tele, because if I had those, as good of a player as I am, I'm sure I could make it sound like that.
Only badly."

+1 on SV...

Oil based Varnish
http://www.luthiersforum.com/forum/viewtopic.php?f=10117&t=33117
http://www.luthiersforum.com/forum/viewtopic.php?f=10117&t=33127

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So how does KTM-SV differ from oil varnish, aside from the fact that it is waterborne? Does it offer the same tonal advantages that the oil varnishes do?

I haven't used KTM-SV except for a few experiments, so most of my comments are based on generalizations about waterborne "varnishes". I'm not a chemist, or an expert on finishes, but here's the basic concept.

KTM-SV is polyurethane based. (not a generalization). Technically polyurethane is a "varnish" but most oil based varnishes used on guitars are aklyd based. Aklyd is more flexible than polyurethane.
Oil based Varnishes, including "polyurethane" varnish cures by the molecules cross linking, creating a solid film.
Waterborne Varnishes contain ground up molecules that have already cross linked. They're suspended in water (and usually glycol ether or some other solvent, which is hazardous, and isn't water) When the water and solvents evaporate what's left coalesces, or kinda melts together. It isn't as permanant of a bond, and also isn't as solvent and chemical resistant as other cross linking finishes. Hopefully Laurent, Howard or some other smart person will read this and do a better job explaining than I have. I believe someone from Grafted Coatings have visited the forum. Maybe they can explain the whole cross link vs coalesce thing.

A couple years ago I experimented with some waterbornes, and even finished 2 guitars with waterbornes. (not KTM-SV) I've since refinished both guitars with solvent based finishes. Waterborne finishes are basically in their infancy. Someday they may be excellent waterborne finishes, but personally I don't think that day has arrived yet. Recently I experimented with some KTM-SV. The only way I could get good adhesion on (oily) Rosewood was to use a catalyzed urethane barrier coat. The catalyst for this barrier coat is isocynate based. Isocynates are very hazardous, and dangerous. I see no need to (what I consider) risk using a waterborne finish if I'm going to use a hazardous sealer. I use no sealer with the oil varnish I use, but on oily woods it can take a little longer than usual for the first coat to cure.

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That was a great explanation, Woody. Thank you!

Target Coatings EM6000 - there are plenty of threads on this finish. A number of people get excellent results with this finish..

www.TargetCoatings.com

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+1 on the EM6000.

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http://www.casperguitar.com

+2 for EM6000

I finished one guitar with KTM-SV and one with EM6000. I am happy with the results from both products. I found the EM6000 a little easier to spray. With the KTM-SV I had one small spot where I sanded through a layer and had witness lines, but the spot mostly disappeared when I buffed the guitar. The EM6000 leveled nicely and I had almost no drips when spraying. It took a bit more work before I was spraying an even drip free coat of the KTM-SV. But the difference was probably my skill level as I am not an experienced finsih person.

No problem with EM6000.

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Woody, I don't know that I agree with you. I have a couple of guitars that I finished back in my waterborne days that were finished with Target Coatings Oxford lacquer and they are every bit as chemically resistant as anything I've worked with. Like lacquer they will react with alcohol if left on the surface. But in my observation the Oxford at least was perfectly resistant to hard body chemistry. I know that Mike Doolin used to make test panels and cut them into strips and put one against his skin in his waist band to test them because he had strong body chemistry. He never had a problem with any of the waterbornes either, and he and Greven probably have more experience with them than anyone because they were the two folks who figured it all out.

We can debate about how the finishes look -- certainly early waterbornes suffered from blue tints which has mostly been addressed. Certainly the most problematic issue remains how they bond to a surface. Solvent based finishes seep into the pores, pop the color and figure and build within the pores out case hardening the surface which is particularly important on softwood tops. Waterbornes do none of that. They don't pop the figure and they don't case harden the tops, thus necessitating the use of epoxy as an intermediate to accomplish this component of finish protection. However, the actual waterborne films buff out to a perfectly acceptable downtown gloss, they are resistant to body chemistry and are both hard once cured and flexible enough for use on acoustic guitars.

Dave,
That is very encouraging. I used water based finishes on myfirst few guitars. I got good results but stopped when one of them developed issues on the back of the neck and on the body under the players forearm. That was CrystaLac. I have some KTM-SV but I'm affraid to use it now. I would love to use a water based finish.
Do you use a water based finish now? If so would you mind sharing which one?

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"An adventure is only an inconvenience rightly considered. An inconvenience is an adventure wrongly considered." G. K. Chesterton.

IME pretty much any finish is more solvent, (and other everyday "stuff") resistant than Nitro so I suppose I shouldn't knock waterbornes for that. Like I said I haven't messed with alot of waterbornes. I have automotive painter friends who have horror stories about waterborne automotive finishes. I agree that's like comparing apples to oranges, but enough of a reason to keep me away.

Hasn't "Oxford" lacquer been discontinued?

I'm also pretty sure that Doolin, and/or Greven are no longer using waterbornes. You'd know better than me, aren't they both using Polyester now?

I didn't mention Polyester as an alternative to KTM-9 because Polyester isn't a DIY finish.

_________________
I didn't mean to say it, but I meant what I said.
http://www.brackettinstruments.com/

Steve, are you concerned the KTM-SV may not adhere well?

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Formerly known as Adaboy.......

I had chemical erosion issues with KTM-9, which is an acrylic I believe. So is EM 6000, and that's why I've been afraid to try it, despite the positive feedback here.
KTM-SV, on the other hand, is a urethane. I have it on one of my daily beat about gig guitars, and it is holding up very well, no chemical erosion, good feel under the hand etc., and seems to be reasonably durable as I do not baby my gig guitars at all. You cannot apply it directly to bare oily woods of course, but others are much more qualified to speak about that kind of thing than I...

Thanks all for the great recommendations. Sounds like the KTM - SV and EM 6000 will both be good options. I think I'll lean towards the KTM - SV

One followup question. The half finished guitar currently has some KTM 9 on it. (just not enough).

Is it a terrible idea to simple spray the KTM - SV on top of the KTM 9 that's already there, or do I need to strip the guitar down to the filler? Other option? Maybe a barrier layer of shellac? Thanks.

No - I worry about it not holding up to user’s particular chemistry. If a player’s sweat is aggressive, I worry about it causing the finished to bubble up where they frequently touch it - back of neck, under forearm on body. (That is adhesion, but not from a mechanical sense - more chemical.)

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"An adventure is only an inconvenience rightly considered. An inconvenience is an adventure wrongly considered." G. K. Chesterton.

Time will tell. Is it worth the risK?

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"An adventure is only an inconvenience rightly considered. An inconvenience is an adventure wrongly considered." G. K. Chesterton.

Steve,
I feel confident that SV will be ok for handsweat. I did have troubles with the KTM -9, and that's why I stopped using it. My guitar with SV is still golden after 1 1/2 hrs of frequent use. It is a urethane.

Corky,
Matt at Grafted coating will best be able to tell you. Usually answers in a timely fashion.
Here's my guess though, don't do it directly on the KTM 9 as one is acrylic and the other urethane. However, a solid barrier coat of dewaxed shellac may be adequate. But I'm guessing mind you, so caveat. I'd email Grafted Coatings directly..

I would think KYM-SV would be fairly inert since it's a urethane. I would guess it to be better than acrylic or nitro lacquer in this regard. So far it's holding up well on the neck and body of the single guitar I've used it on. I'm guessing meddlingfool meant to say his finish has held up well for 1.5 years instead of 1.5 hours<smile>. SV has a great feel
on the neck.

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Formerly known as Adaboy.......

Ahem..
Yep, years...

Not so. A number of us DIY'ers on the OLF are using UV cure polyester finish. We're getting pretty good results these days, but granted, we are still working to perfect things (like product flow, nibs and dips, etc.). Don't discount it yet.....

Regards,
Dave F.

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Cambrian Guitars

"There goes Mister Tic-Tac out the back with some bric-brac from the knick-knack rack"

Doolin got away from waterbornes, switching to polyester. Greven, I doubt did because he had chemical sensitivity to nitro, hence the switch. I know that Gerald Sheppard is using waterbornes as well, although which one I don't know. I stopped using them because Target had changed their formula and I was having problems spraying it and a friend turned me on to a conversion varnish so I could still get guitars done for one of the festivals in time.

If it's Polyester, reguardless of whether it's catalyzed or UV cured it contains Styrene. Please read this MSDS before using it without the proper safety equipment.

http://www.sciencelab.com/msds.php?msdsId=9925112

I've used polyester on necks for a few years. I occasionally use it on bodies too. I have a explosion proof fan, use a hooded resiprator and wear a tyvek suit when spraying it.
The difficulity or ease of application isn't why I say it isn't a DIY finish. Proper safety equipment is necessary.


David, I'm pretty sure Greven uses Polyester now, at least on guitars he doesn't French Polish. I've never used conversion varnish, but I've got a cabinet maker friend who loves it. (I think he uses Mohawk)

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I didn't mean to say it, but I meant what I said.
http://www.brackettinstruments.com/