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It was the KTM-9. I used Target Coatings products after that. USL and EM6000. I like nitro the best but would rather not use it in my work space. The EM 6000 seems to be a good replacement.

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Wisdom is justified by her children

I too am using the Em6000 and loving it! Should you happen to have any mistakes in spraying, they'll sand out nicely in a day or so - a very forgiving finish.

Mark,

I have never used KTM-9 and never had a desire to, but KTM-SV is an outstanding finish. As I stated in my post above, KTM-SV is a completely different animal than all of the acrylic based watebornes including KTM-9 and EM6000. My guitars are "out there", so I have to have full confidence in my finish. I've worked with Target products for over 6 years before finally giving up on them. When I asked pointed questions about their finishes I often got very indirect and hedged answers. Sorry you had a bad experience with KTM-9, but don't throw the baby out with the bath water.

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Randy Muth
RS Muth Guitars Website
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Is there a place to buy KTM-SV other than directly from Grafted Coatings? (IE, a cheaper source)

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Formerly known as Adaboy.......

LMI is now selling an 8 ounce can for an introductory price. I buy it by the gallon from Grafted Coatings. You don't really want to save a few bucks on the finish. The value of the guitar totally negates the extra couple of dollars. For comparison, while KTM-SV is more expensive than EM6000, it is less expensive than EM2000, which is a more directly comparable product.

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Randy Muth
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Thanks Randy.

What kind of shelf life does the KTM-SV have? And is the shelf life shortened significantly once the can is opened?

Is 8 oz enough for 1 guitar or is a quart required? I guess the size container one buys is directly affected by answer to the shelf life questions.

For a first time guitar finisher with no previous spraying experience, is the SV or 6000 easier to spray? I'm referring to ease of setup and adjustment of the gun to get good results.

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Formerly known as Adaboy.......

I have not sprayed KTM-SV so I can't answer on that one, but I have sprayed 3 guitars with EM6000 and it is very user friendly. It levels out nice, and buffs out nice, but it does need to be dry sanded and not wet sanded before buffing. The pictures are of the first guitar I sprayed with EM6000. You sure can see that ugly table cloth reflecting in the back and a very sideways shot of the soundboard, again there's that ugly table cloth.

I don't keep any finish more than a year after it is opened. How much you need will depend on a number of factors, but I would not feel comfortable with just one cup on hand. Both finishes spray and level nicely. Gun settings and technique need to be figured out for whatever finish you are using. If you have never sprayed before, you definitely will want to practice on a scrap piece of wood. I would take it all the way through the finishing process, complete with buffing. Typically with waterbornes, you want to hold the gun a little closer to the piece, about 4-6 inches and keep the gun perpendicular to the piece. Also you do not want to dry spray, you want a fairly wet spray (relative to solvent based finishes), but you don't want runs. Check your work 10 minutes after spraying and wipe any runs that you see. Don't worry about the smudge, it is far less thick than a run and will disappear after several more coats. A run won't. That's just a couple of things particular to waterbornes, but there is lot to learn about spraying in general. Learning how to finish a guitar properly requires a considerable investment in time and money for a proper spray set-up. That said, the rewards for learning how to spray a finish are great. If I was only doing a couple of guitars, I would probably contract it out. There are expert guitar finishers that are very reasonable. I already already made my investment in time and money so I'll just keep spraying for now.

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Randy Muth
RS Muth Guitars Website
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Randy, thanks for sharing about the KTM-SV. I hadn't even heard about it before but you've got me sold on it. I think I'll give it a try on my next one.

I have a question about your finish schedule. You mention spraying the first and second sets of coats with 2 hours between each coat. How many coats do you typically need for each set. (i.e. 2 sets of 2 coats, 2 sets of 3 coats, or...)

I'm pretty new to spraying (I sprayed a cradle last summer and that's it) but it's definitely something I'd like to get good at.

Thanks.

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-Clint Beacock

Clint,

You typically get about 0.5 mills per coat and I try to wind up with 4 mills on the top and maybe 5-6 mills on the rest of the guitar. So I spray 6 coats per set for a total of 12 coats, but only 3 or 4 coats on the top in the second set. Once you add in two level sandings that pretty much puts you on target. You can measure how much you are putting on per coat by pealing the film off your soundhole cover after the 1st set of coats and measuring the thickness. If you have good air circulation and good humidity control you could spray every 1.5 hours without a problem. If you don't have good humidity control, don't spray waterborne on a humid day.

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Randy Muth
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Mike I probably shouldn't, but assuming your using compressor for finish. Have you heard about hvlp unit (I have 3 stage Wagner) Shouldn't matter once used to it just wondering. I have been debating on the "EM6000, but the acrylic thing compared to the Grafted SV stuff may swing me to what your doing. Mind if I give you a call?

Stan, are you asking me or Mike? It seems like your question is directed at me, but my name is Randy. I just didn't want to ignore you if you were addressing me. I'm the one spraying KTM-SV.

Just to be clear, everyone who is spraying guitars is using HVLP. It's just a matter of whether they are using a conversion gun with a compressor or a turbine system such as you have. A conversion gun takes the high pressure of a compressor and converts it to a high volume low pressure (HVLP) system. A turbine starts out at high volume low pressure. I use an Accuspray 3-stage turbine that is probably similar to yours. A lot of people don't like turbine systems for spraying guitars, but it is what I have and it works quite well. I think the main reason people don't like the turbine systems is that they are mostly familiar with bleeder guns. These are guns that continually pass the warm air whether or not you are pulling the trigger and spraying. These are not good for spraying guitars especially waterborne. My gun is a non-bleeder gun. So as long as you have a quality non-bleeder gun you should be fine. I posted my finishing schedule earlier in this thread.

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Randy Muth
RS Muth Guitars Website
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Rand sorry for the mix up. I have sprayed many guitars with my Wagner and never a problem. I didn't know most of the SV stuff done with hvlp and good deal for me with 3 stage Wagner. Here is one more question. I seen LMI with 8oz special. How much is needed on guitar? I am sure in one of the post in this thread also (like dumb @ss didn't read before asked) on schedule. Is the flow about same as other finishes noting I have it setup well and have used with good effect on a previous waterborne's and nitro. Lot of change in the gun setup for flow? I know should and will test and shoot scraps before guitar, but thought would ask

Stan, I've never used KTM-SV but I doubt 8 ounces would be enough to spray any finish. Spraying wastes alot of finish. I'm pretty sure 8 ounces would finish a guitar using a brush, but like I said I don't have experience with KTM-SV.

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I didn't mean to say it, but I meant what I said.
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Randy,
Reading your schedule, I didn't see a pore fill step. Is the isolante enough to accomplish this? Also, you mentioned that the KTM-SV has problems the same as varnish. I wonder, could you briefly outline a few details? How does KTM-SV smell? I was able to spray KTM-9 inside, behind particulate barriers while wearing a respirator. Any vapors were largely negligible, as opposed to the toxic-fumy-ness of oil based/flammable products.
Thanks

I'm refinishing a guitar that had a water based finish. It reacted with the clients skin/sweat and started bubbling up on the back of the neck and where his arm rested on the body. I used Crystalac. Their Super Premium is listed for instruments. I have made 6 guitars with it and this was the only one with a problem. I obviously stopped using it when I found the problem.
- Does anyone know if KTM SV will have this problem?

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

The KTM-SV is gaining some popularity as an instrument finish. Rolfe Gerhardt over at the mandolin cafe sent me their finish schedule for it. I havent used it yet though I plan to. They speak highly of it use for instruments over regular KTM-9 and other waterborne finish. If you PM me your email address I be glade to send you the word document Rolfe Gerhardt sent me...Mike

A good photo of the blue cast problem with acrylics can be found here:

http://www.newenglandluthiers.org/conte ... inish.html

Rene

Since the resin in KTM-SV is urethane, I highly doubt it would ever have that problem. But others with actual experience with KTM-SV could give you a more reliable reply.

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Todd Rose
Ithaca, NY

https://www.dreamingrosesecobnb.com/todds-art-music

https://www.facebook.com/ToddRoseGuitars/

Randy, thanks for your detailed comments on KTM-SV. I have had a can of Target's EM2000 sitting around for a while waiting for some testing. I was attracted by Target's specs which state that the EM2000 has an AWI rating of TR-6, as opposed to the USL/6000 rating of TR-3. So I was interested to read your comments on the EM2000 predecessor.

Do you have any idea if Grafted Coatings has tested their finishes for the AWI TR rating? Their web site is pretty useless.

Here is a copy of the AWI (Architectural Woodwork Institute) finishes chart for anyone who is interested in objective finish evaluations: http://www.furniturefinishwizard.com/awi/awichart.htm

Thanks!

I recently used KTM-SV for the first time. After curing for a couple of weeks I wet sanded and sanded through a layer, only to discover the edge of the sand-through was not bonded to the layer below and I actually was able to peel large strips of finish off. Any of you KTM-SV users out there have any thoughts as to what happened? My finishing schedule was:

1. Shellac seal coat. Dried for 48 hours, sanded dull, nice and chalky sanding dust.
2. Four coats of KTM-SV sprayed 45 min. apart.
4. After a week, level sanded with 320 grit, five more coats of KTM-SV, 45 min. apart.
5. Two weeks later, wet sanded to 1500 grit, only to discover above problem.

If I did something wrong, I'm willing to give it one more chance, but I'm reaching the point with waterborne finishes to call it quits for good. Every one I've tried has at least one major, unacceptable issue. I sure hope there's a brilliant chemist out there to develop a replacement for nitro and all the other even more toxic finishes, because one of these days the EPA is going to pull the plug on all the noxious stuff. The upside to that I guess would be we'll all become experts at French polishing.

To reinforce Steve Saville's comment concerning KTM-9, I was quite happy with the result I was achieving with KTM-9 until I too encountered the "bubbling" problem on the back of a neck after a few months of use. As Rosanne Rosannadanna (sp?) used to say, "If it's not one thing, it's another!"
Craig

I'm no finishing expert, but my guess is it was step 3 in your list that did it.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

Craig,

I have used KTM-SV extensively and have never had that problem. Actually I see lots of problems with your schedule and I'm not surprised you had the problems you experienced. I seal with a catalyzed rosewood sealer, but I know Rolf Gerhardt uses shellac. If you read back in this post I gave my schedule. I use two coats of sealer and don't sand it. With shellac you will probably need to use more coats. This stuff does not like certain wood oils. On what wood did it peel up? It seems like you were asking for trouble with just one coat of shellac and then sanding.

Also, I spray my coats 1.5 hours apart, 45 minutes seems a bit tight to me. Might be factor or it might not. You shouldn't need to use 320 grit to level the first set of coats. Seems a bit heavy handed. I use either 500 or 600 grit and even that is pretty aggressive. Four coats only give 2 mils dry. Sanding that with 320 grit is asking for burn through. I spray six coats for my first set of coats.

Waiting a week before the next set of coats is a big problem. After a week the finish has fully cured and the second set will not burn in well to the previous set. You should spray your second set of coats the next day. That is, the morning following your first day of spraying you level those coats and begin spraying the second set.

Also, it is not necessary to wait two weeks to wet sand. I level the second set of coats two day after spraying and bring right up through the grits. I buff one week after I finish spraying. If you are starting with medium compound on the wheel, you may want to bring it up to 2000 grit before buffing.

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Randy Muth
RS Muth Guitars Website
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I have used KTM-9 and USL both for years. I had far better results with KTM-9 than I did with USL. On any darker wood I finished USL always had a noticeable blue tint. I never noticed any with KTM-9 unless sprayed too thick. But we all see things differently. I never expected back then or expect today that any waterborne acrylic lacquer will match up with nitro for hardness. I always found KTM-9 harder than USL. That is just my experience with the two.

Now I have never tried the KTM-SV so can not comment on that. I have tried Em6000 and liked it better than USL. It seemed harder but I still saw more blue in it than KTM-9 but that may have been my fault as I think I sprayed it a little too viscous.

I still can’t help but think, each time I hear someone say they were disappointed in this or that waterborne acrylic lacquer; that in the back of their mind they are trying to compare it to nitrocellulose. That just is not a fair comparison, and they will always be disappointed if they expect an acrylic lacquer to be as hard as nitrocellulose lacquer. One is an apple, one is an orange.

Craig,
I'd guess it was in step 4. Perhaps when sanding you somehow contaminated that surface. Stearated paper, oil, or something that created a film layer that stopped adhesion. If there was contamination in whatever you wiped before spraying, or if that wipe was not fully dried, or you used something to lube while sanding. It is impossible to tell without knowing everything you did.



Thank you for that reminder to not use water-based finish ever again. SV had me thinking. If they would pay for a refinish if it bubbled up, I'd think about trying it.

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