Official Luthiers Forum!

I'm not having any luck in the archives so pardon me for rehashing covered ground.
I am having customers coming back for rework because the back of their necks are starting to blister. My own guitar I've been leaving just to see how bad it will get and it's absolutely horrid. So I'd like to know, is there a finish that I can I apply over top of a water base finish, or will I have to remove the neck and go all the way down to wood and start over?
KTM-9, you're fired!
Thanks for any info

Blistering!
I've been using that H2o stuff for 12 years!
Even though the directions say you can coat every 2 -4 hours -
I've found that only 2 -3 coats a day at least 4 hours apart works well!
It also depends on how heavy(thick) you apply the coats!

Blistering can be caused by to much finish -applied to quik -and not enough time for the liquid medium to evaporate!
You may have a comtaminated finish!
Have you used any oiled steel wool ?
Naptha?

Mike

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Mike Collins

When I started building I was looking for a finish that would be safer to use than nitro. I read good things about KTM-9 and Mike Doolin's endorsement and published finishing schedule really helped sway me.

So I KTM-9ed up, bought several cans, a nice metal strainer, a compressor, spray gun and everything else that Mike recommended.

Then I started reading about troubles that OLF members were having with the finish.... Some reported that it was coming off on the neck and one poster reported that the chemistry of his arm (or deodorant) resulted in the finish coming off where his arm holds the guitar.

The last straw for me was when Mike retracted his endorsement and if I recall correctly he even weigh-in here and indicated, eloquently, that he was no longer going to be using KTM-9. I still can't understand why LMI's description of KTM-9 sounds and reads like Mike is still endorsing this product........ And let there be no mistake I love the folks at LMI - I am just confused at how KTM-9 is being represented after Mike's retraction of his endorsement.

That did it for me, KTM-9 was fired here too before I even tried it..........

To me a standard for guitar finishes for our guitars has to be as good as what the fa*tories have traditionally used. No exceptions except one - if the guitar is for you and you don't mind having to redo or touch up the finish in time or if it is a french polish and you as the builder are willing to support repairing the finish for your customers in perpetuity.

For the entire time I have been an OLFer what finish to use that is safe and provides great results has always been a problem for folks that lacked the proper environment for nitro or some of the newer finishes like cat poly. And I still don't see a good solution either.

No offense intended to KTM-9 users who are satisfied with the product.

Med if it were me I would refinish the guitars with something that will last and perform for many years without any issues.

I'd think about taking the necks off and re-finishing with Tru-Oil as one option. I bet the bodies will hold up reasonably well.
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.

Yikes! I just finished my second Greek bouzouki, and sprayed KTM-9 on it. The previous instrument was completed a year ago, and shows no signs of blistering, although it is not used much, since it was made for my 6 year old daughter. The finish on both instruments turned out really spectacular, so I hope that they doesn't blister. I pretty much followed Mike Doolins instructions, with epoxy filler, etc., sprayed 6 coats, one per hour, sanded the next morning and sprayed with alcohol and 6 more coats one every hour, then let it cure for two weeks. I have had many enthusiastic comments on the quality of those finishes.

I was not aware that Mr. Doolin is no longer a fan of KTM-9, or that there were problems with adhesion (if applied correctly). I have seen some other water based lacquers, marketed for musical instruments, one being a water clear finish from Oxford. The other, I saw in a catalog, and of course, I can't find it now in the big pile in my workshop. Anybody have any info on the Oxford.

I have considered nitrocellulose, but I bought an HVLP for the KTM-9, and have never been able to get answers to some of my questions regarding nitro. My questions are these:
1. Can I spray nitro with an HVLP sprayer, or do I really need a compressor? I had a spray gun sales person tell me that unless I bought a really big compressor and ran 50 feet of pipe, and then a hose and had a very expensive air filter to remove water and oils from the air, it would not be worth trying a compressor and gun to spary with.
2. What exactly is a blast proof fan, how does it differ from a regular fan? I have a whole house fan in my garage (for some strange reason, which nobody can explain), and I make a paint booth out of a plastic tarp and throw an air filter over the whole house fan when I spray the KTM-9. Works great for the KTM-9, but I don't really want to blow up my house if I switch to nitro. Plus I like the fact that the water based finishes are better for my lungs (mild asthma, although I do always wear a respirator) and for the environment.

I make about one or two instruments a year, right now, so what does a guy like me do?

I had the same problem with KTM and had to pull off a neck, strip it down and finish it with Tru-Oil. So far, the body has held up well. I switched over to Target's Ultima product and like it better- cheaper and seems to go on easier, but I won't use it for a neck.

The water-based products aren't flamable and won't ignite and explode, therefore a spark-proof fan is not needed. You most definitely need to keep the stuff out of you lungs, though.

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It's not the miles ahead, it's the stone in your shoe


In Markham,Virginia

An explosion proof fan is required for spraying nitro: Explosion proof fans have totally enclosed electronics so no spark can ignite explosive vapors. It's been a while since I was looking for one but I think that the blades are also manufactured in such a manner as to avoid a static spark as well.

They are expensive with new ones being in the $300 - $500 range for a small one.

I know that some get away without one, I did which was not smart on my part....., but for posting on a public forum where someone is going to try anything that might be suggested it's a good idea to just agree that an explosion proof fan is a requirement for spraying nitro.

Also, the white dust that gets everywhere when spraying nitro is exactly the same stuff that the battleship New Jersey used to launch 3,000 pound projectiles - the dust is explosive too - be mindful of pets, family, neighbors please.

Lastly we are very lucky to have guys like Joe White available to us. Joe will provide a finish that some of us believe to be the best on the planet for a nominal charge with a civilized turn-around time and superb customer care. We work very hard to produce great instruments that I think are deserving of an excellent finish too. The first thing any prospective customer is going to see when they pick up your instrument is the finish - do it proud.

I used KTM-9 on 2 guitars 3 years ago and they are holding up just fine. I don't care for the feel of the neck and have now gone in a different direction.

As far as Nitro spraying at home...make sure you have a proper spray booth and be mindful of the toxic outgassing for weeks. If you're already susceptible to respiratory issues, forget Nitro!

For the hobby builder, give some consideration to French Polishing Shellac. I've done 4 of them and it was a wonderful experience and the results were quite satisfactory. And it's safe.

I agree with Hesh...for the ultimate finish and convenience, go with a Joe White Poly finish. There is absolutely NO better finisher in the world!

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

Hey Folks , thanks for watching! Aside from my kvetching about the product (Hey, why are they selling a product known to be defective as a Really Great Thing?)...what I need to know now is, what type of finish can I put on top of a water base...will True Oil or shallac bond with it?
Again thanks for any help...and by the way, the body of my personal guitar is not holdong up well, it's blistering where it sit's on my leg and where my arm rubs it.
*&%$#@!

Med buddy I would not call KTM-9 defective - it works very well for some of these guys who seem to have the technique and schedule down. But I do agree that it is not a forgiving finish if one deviates at all from something that works well.

Being a deviant myself I thought it better to go with something more forgiving.

A number of years ago I used Crystalac on a few guitars and had satisfactory results. None have exhibited problems in the areas where they are handled. When KTM9 hit the market and I began to hear great things about it, I switched over. I have guitars finished with it where you can't tell the difference from nitro. But after a year of being handled (mostly back of neck) the finish becomes rough to the touch -- almost scale-like. I will sand back smooth and apply Tru-Oil.

There isn't one finish out there that does everything we need it to. It just depends on what demon you're willing to live with.
Craig S.

I have nearly 20 guitars out with KTM9 on them. Not once have I had a failure. Too little info given to know for sure but to blister after the guitar was delivered sounds to me like a heat exposure issue. If it did not blister during cure out I doubt that the issue is the material it’s self.

By the way, what I understand that Mike is allowing LMI to continue to use his endorsement of KTM 9. The fact he switched to a catalyzed finish does not preclude his endorsement of KTM9 as a viable product. If mike had an issue with the product that would make him with draw his endorsement I am sure LMI would have pulled it long ago.

I used KTM9 on my daily player three years ago. It is showing a little wear near from my thumb in a few spots near the fretboard, but no blistering. I don't particularly care for how it feels, though. I've since switched to Behlen's Rockhard Tabletop Varnish for necks.

Pat

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formerly known around here as burbank
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http://www.patfosterguitars.com

I really don't think it is a heat issue, as I've never let my guitar become heated. I bang it about vigorously on stage frequently (hey ho drunken product testing ha) but otherwise treat it the way you would an expensive handmade guitar. I understand that some of the first poly's and even occasionally nitro can turn to gum under certain players hand, but this seems to be a sweat / chemical issue as it only seems to happen to some of the people. I don't think it is an application issue as I've followed meticulously all instructions. I guess you could call it a successful product if you like, but anything with a 15-20% failure rate is unaccepatable.
To be fair, I haven't yet contacted either the maker or the retailer for their comments, but we'll see, I must consider that it could also be something that I have done.

I have to say Inever put KTM9 on necks, not be cause of failure but because of feel it is to plastic feeling on a neck. but on the bodies I have had nothing but success. It has proven to be a good wearing very forgiving product in my experiance with it. As far as personal skin and sweat issues I seen that with shellac Tru-oil anadn other finishes as well. So I can't justify that as a product failure rather just one of those things. I have read a good deal on issues with waterborne finishes, They are not perfect by any means but I seriously doubt that KTM9 is experianceing anywhere near a 15% failure rate. It has been around for many years now and before it KTM4. If the failure rate wass anywhere near 15% it would have died long before now. Now when a faiure happens to you it is a 100% failure rate to you and I understand that.

Blistering is a result of a contaminated finish -or the surface it's being applied to!

Mike

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Mike Collins

Hear Hear!!!

I was going to say but got side tracked, that every time I have seen ph corrosion or softening (sweat induced softening) blisters is not what I see. In stead I see finish pealing or being pushed away from a pressure point and gumming up. I am with Mike here. If blistering then the issue is heat or contamination at application either the finish or the surface.

Hmmm...
I will try to figure out how to post some photos of the guitars in question. I'm not sure how I could have contaminated anything though, all my finishing is done in a hyper clean sealed environment, the finish goes straight from the can to the gun, my lines have a water/oil trap with only six feet of line post...I'd love to believe it was something definable I am doing so that I could stop doing it, and then feel comfortable using it again. I love how it looks and works, but for now I can't trust it and am paying someone else to finish my guitars, which saddens me.
And, I also wonder, if the finish was contaminated, why has it taken 18 months to show?

18 months!!!!!
I must have missed that part!
Contact with some oils & chemicals can still cause this!

Some people have a chemistry that turns strings a nasty color with just hours of playing on them. & kills the new tone of them!
Contact with body sprays,deodorants-oils & prefumes can also have a similar effect.
I seriously doubt that anything you did caused this!!!
The enviroment that the guitar has been in is more likely the cause!
Stripping -cleaning with Naptha and refinishing should help-BUT if the player uses any chemicals for ease of playing or body sprays it'll come back!

Mike

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Mike Collins

Conventional wisdom along with some real life experience is that a water borne finish is OK under a solvent based finish because the waterborne doesn't continue to offgas solvents that then have to go through other layers of finish. The other way around doesn't work.

That said, if you have blistering, I wouldn't try to put anything on top of it, particularly if you don't know the cause of the blistering. No sense in putting a nice new layer over a bad substrate.

If you are planning on sanding back to the wood and just worrying about residue left in the pores, you should be fine with shellac, oil, or nitro.

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http://www.chassonguitars.com

The blast proof fan is built so gas and vapours cant enter the electrics and ignite.

I think as long as you keep nitro well ventilated you shouldn't be getting explosions. At concentrations that can sustain an explosion you will most likely be knocked unconscious or worse. However do wear a chemical respirator when spraying nitro even when outside. The stuff and the solvents used are somewhat toxic and will cause many nasty damage not to mention that if you breathe too much of the stuff you can die. Some people did die from painting in poorly ventilated area.

I use nitro though because they're cheap here (5 bucks per quart) and they work quite well and I never had any issue with it. The wasterbased products I have used (Varethane and stuff) seems good when you first use it but they don't seem as shiny as their nitro counterpart and what's worse, their water resistance isn't very good, if you let a droplet of water sit on the dried/cured finish for too long that spot turns white. Also waterbased product doesn't spray well (high psi needed) compared to nitro.

The only problem I have with nitro is they take forever to cure and shrinks forever too. So if you're painting grainy wood like swamp ash you need to grain fill.

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Cat-gut strings are made from kitten guts, stretched out to near breaking point and then hardened with grue saliva. As a result these give a feeling of Pain and anguish whenever played, and often end up playing themselves backwards as part of satanic rituals.

Typhoon Guitars
http://www.typhoon-guitars.com

Like Mike said if it took 18 months to show then the issue is post finish environmental. It has to be a chemical reaction to something that has come in contact with the neck. If the contamination happened prior to application, you would have had issues even before it cured out or shortly there after. Blistering as in puffed out bubbles is most often seen due to direct sever or prolonged heat like a lamp but could be a chemical reaction as well.

No doubt if it took this long to happen then the finish was not faulty but has encountered some where down the line an environmental induced problem.

Does the guitar set on a cheap guitar stand with vinyl tubing padded rest support at the neck where the blister accrue? I have seen vinyl cause blistering in several types of finish.

\To post a photo reduce the image to 250KB open a reply at the bottom of the page you will see file name, a field for the file name and a browse button. Find the file then hit Add File. This will load the photo into a queue that will be seen on the main part of the page. Click this queue when you want to post the photo.

I do the same. I let the guitar hang in my garage for the initial offgassing...then I hang it in my basement next to an open window.

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Jeremy Vonk

I am a water base fan. Couldn't pay me any sum to use anything as toxic as nitro. Kiss your liver goodbye in my books. I guess nitro can be used safely with good precautions. You might not want to but you could drink a waterbase finish and survive. I do not think the same could be said of solvent based finish. I think nitro does give a better finish. That aside, i have been using ktm9 with good results. it is a more difficult product to work with than nitro but i think the health issues make it worthwhile.

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Greg
http://garibaldiinstruments.com/