Official Luthiers Forum!

It seems some time back there were quite a lot of discussions regarding KTM-9. Even something about Mike Doolin using it, then not using it... Yet LMI still quotes Mike. Just curious, anybody using it? Happy with it? Does it require spray equipment and a booth?

Mike

Mike Doolin wrote a very comprehensive article on KTM-9 over West System epoxy sealer. It may be still posted on his web site, or you can get it from a back issue of American Luthier. I believe he is currently using catylized poly.

The people I know that have used the water base all used spray equipment without a bonafide spray booth. That was one of the primary reasons they were using the water base. They have all switched back to nitro or poly.

Doug

That is what I remember hearing. The question is, why did they switch back?

Mike

Mike,

If you're going to use a waterbourne, IMHO Target's USL is a much superior product. Dries harder, 100% burn in and available directly from the manufacturer.

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Jimmy Caldwell
http://www.caldwellguitars.com

My experience goes with what Jimmy says.

Mark

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Wisdom is justified by her children

There is a great deal of info and experiences in the archives regarding KTM-9.

Although some folks do fine with it others had problems. The most common complaint that I recall reading was that it is not very tough a finish. One OLFer reported that it came off on his arm several months later.

Again others do fine with it and use it today.

Mike Doolin was a big proponent of KTM-9 and the primary reason why I KTM-9ed-up several years ago. After reading the complaints from others and reading an announcement from Mike that he was no longer using it I never used what I had here. I have been wondering too why LMI still lists Mike as effectively endorsing KTM-9 when he no longer uses it himself. Perhaps in the water based world he would recommend it but no longer uses water based finishes himself - I don't know.......

The big promise of any water based finish was the huge reduction in toxicity but I think that most would agree that water based finishes still don't stack up to nitro, cat urethane, or cat/UV poly for toughness.

Well, thanks all. I was not planning on using it... I was just wondering why Mike was still an endorser at LMI when he clearly gave up on it back in 2006. His article BTW, provides excellent pre-finishing information.

http://www.doolinguitars.com/waterborne ... tions.html

Mike (PS: I was not trying to start yet another WB vs Nitro vs Cat vs etc... thread, plenty of those in here! just looking for an update)

I've used both and like USL better. You can get a very attractive finish with it. Not quite the depth or clarity of nitro or poly but close. It's a great product to use starting out. The reality however is that waterbased stuff is still not well accepted in the commercial market because of durability concerns.
I don't think it's that great for necks and have had breakdown issues there. The bodies I've done have held up surprisingly well. I think USL on the body and an oil finish on the neck is actually a very reasonable way to go. Especially if you are just building for yourself, friends, etc. I believe there are some high end luthiers still using USL though. Gerald Sheppard comes to mind. I know last year he still was. He posted his finishing schedule on this forum a while back. That said, most of my stuff gets nitro or poly these days.
If you do use KTM9 or USL it's best to spray it. Some kind of a booth with exhaust is nice but I think Mike just sprayed it out the window. It's pretty forgiving stuff.
Terry

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It's not what you don't know that hurts you, it's what you do know that's wrong.

How hard is USL? (compared to Nitro)

What about sweat resistance?

Mike

Mike,
I don't have large numbers of either finish "out there". I did do around 6 or 7 with KTM9 and the bodies held up fine but every neck developed problems over time. Mainly getting gummy in areas. Some worse than others. I've got a couple of USL bodies and necks being used a lot and are OK so far but they are just a year or two out. The guitar that I use and gig with has KTM9 on the neck and body, it's 6 years old and gets a lot of use. Gets played at least an hour or more a day. The body is fine, the neck is getting a little rough in a few areas. You might want to e mail Gerald Sheppard and see if he is still using USL and how it's holding up.
From what I've seen and learned from other builders, hardness and sweat resistance is definitely going to be less than nitro or poly but probably acceptable for more casual players that take good care if their instruments.
Terry

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It's not what you don't know that hurts you, it's what you do know that's wrong.

I've used Targets USL on furniture and on my first guitar, with excellent results - if you want the properties of nitro, you can get pretty close with USL...

They also have a water-based poly called SC9000 that is a very hard finish and has excellent clarity - they also have a great water-based Varnish called hybivar. I will probably try the SC9000 on a guitar I'm making now - will post pics when I'm done of course...

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Mitch

Be careful about assuming that finishes which work on furniture will also be fine for instruments. The KTM-9 and USL finishes that are recommended for guitars went through some extensive testing to determine that they could withstand the expansion and contraction seen from changes in seasons and humidity. Mario was one of those testers and he actually subjected his guitars to extremes outside of his shop in the dead of winter before he would accept a finish. Many of the great furniture finishes failed because they lacked the necessary flexibility.

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JJ
Napa, CA
http://www.DonohueGuitars.com

Mike started using cat urethane I believe in 2006. In as far as I have read he has never disvalued KTM9, just changed his preferred product of choice.

We all have different opinion on KTM9 vs USL (Stewmac ColorTone) I first started with USL I got great results in as far as the finish except for one very aggravating thing for me. USL produce a noticeable blue tinted film. This is a common complaint with waterborne finishes. I switched over to KTM9 and did not have that issue. I also felt the burn in was excellent for a waterborne. Jimmy found things to be the other way around. I found KTM9 to be less rubbery to the touch and I am sure there others that found USL to be less rubbery. I found KTM9 to sand better than USL and I am sure there are others that disagree.

I still use KTM9 regularly for 4 years now

After french polishing my first, I've only used USL on the next 5 (which used up one gal. by the way). I've been happy with it as a viable alternative for me to having a full blown nitro setup. On this last one, I put 1 drop of amber in each full reservoir (touchup gun) for the clear coats, which I think will help the "blueish" thing. The forum on the Target site has lots on sweat resistance, hardness etc.

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Dave
Milton, ON

Question...Is target USL the same product as Stew-Mac Color Tone?
I've done 10-12 guitars with KTM-9, only one problem with one neck on my personal not at all well cared for guitar, the body is fine. I just assumed I did't apply enough coats and had worn down to the epoxy. Can some one point me to a good thread about applying oil finish?

Yep as I said earlier ColorTone is Target USL

Re: Bluish cast. It's been my experience that the only time I ever get a bluish cast has been when I applied a coat too heavy. Remember that you don't apply a finish, you build a finish. Waterbourne (or any finish for that matter) produces a superior finish when applied in thin coats with adequate time between coats. There's a lot of variability in what constitutes a "coat", depending on individual spray techniques and equipment. I've had the best results with multiple sessions of relatively light coats. Just my .$02.

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Jimmy Caldwell
http://www.caldwellguitars.com

Man am I glad I didn't see this post last week. I just completed buffing out my first guitar using KTM9 and couldn't be more happy with the results. I think this is by far the nicest finish I've been able to achieve. As to longevity, who knows, but I can say it seems WAY more durable than the FP that I usually do, and I was able to spray the entire finish in my garage with no woories about the toxicity, etc.

The pics below don't do justice, but I do have to give props to Bob the Zootman for the flamed mahogany as well as finding me a matched side set after I cracked the first.





Cheers!

John

After reading this, I have to asume that the neck is the big problem. Perhpas a traditional finish there with KTM-9 elsewhere. I would be interested to here MichaelP's thoughst on longevity.

Mike

Glad Terry Kennedy confirmed that I'm not alone with KTM-9 failing on the neck. I thought maybe it wasn't pore filled well enough. Who knows. It seems to pop on the grain; same size as the grain too. I have sanded it smooth 2 or 3 times in the past couple years with 1000 grit for a satiny feel. Tonight I just grabbed a peice of 400 grit. Handy. I'm willing to strip the neck and do something else on it.

Anyone tried putting something over the top of KTM9 to prevent further failure? Shellac then nitro? If I can avoid stripping, cool. BUT, I have nothing to lose by experimenting. After a couple more sandings, I HAVE to refinish....

I've had the same problem exactly, bubbles appearing on the grain ends then coming through the finish, at first at the first position and the all of the neck. Slightly worried, as this is the only ktm-9 guitar I've kept. I was wondering, due to the correlation of the grain and the bubbles if it might have more to do with the sysem 3 epoxy filler. I've had no troube with the body, and I treat it very roughshod.

I too have experienced gumminess with Colortone. My wifes uke gummed up. I haven't experienced it with mine so I wonder if its related to a person's perspiration? I have also used French polish on the neck and not experienced any problems. Paradoxically, I have had problems with True Oil on the neck. Not trying to be different.

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A higher purpose for wood.
Rich Smith
Issaquah, WA

What sort of problems have you had with Tru-oil Ricardo?
Terry

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It's not what you don't know that hurts you, it's what you do know that's wrong.

Terry, it turned tacky on me. The best feeling neck I've had so far is a French polished neck.

_________________
A higher purpose for wood.
Rich Smith
Issaquah, WA