Official Luthiers Forum!

I'm in the process of switching over to KTM 9 from laquer.   I'm having a hard time getting a good even coat sprayed on with my hvlp gun. I've read all the instructions and filled and sealed everything, the finish is drying well and sands out fine to a good gloss. But I keep sanding through in spots when leveling (especially on the sides).   This is surely because the coats I'm spraying on are not smooth. In the past with laquer I've been able to find that sweet spot where you get enough on for it to get glassy and smooth but it doesn't drip. Whith the KTM 9 its either grainy or dripping, nothing in between. I've tryed a bunch of settings for my gun (a little less flow helped a bit) and various spraying distances and speeds with no signifigant improvements. As I sprayed, I was flushing my gun with water between coats (as the instructions say) but noticed a bit of buildup on my nozzle which was making my coats even more uneven, so I switched to flushing with alchohol and hand cleaning the nozzle after every coat. This helped keep it from getting worse as the day went on, but I still am not getting the flow I'd like to. I've read that KTM 9 self levels, but everytime I put enough on for it to do this, it drips. I've thought about finishing each surface indifvidually so the guitar isn't hanging vertically, but this is too time consuming of an option for me. I've recoated the areas a couple times and after much effort achieved a good finish, but need to find a permanent solution (or switch back to nitro). Thanks for your help

Just spray it on a little dry, bumpy, and grainy, build up the depth you need. I put 6 to 8 coats over z-poxy and then wait two weeks. It looks terrible, and you will be sure you've ruined everything. Then sand it flat, start with 1000 abralon (from the auto parts store), 2000, 4000, buff with medium grade compound, then final polish. I swear its almost magic but its beautiful. I've done four now and have not had a failure yet. Its really scarey but follow the instructions posted on LMI, it works! Good luck, MIke

_________________
The Biggest Little City, Nevada
www.hammondguitars.com
I love building guitars!

When I was spraying KTM9, I had the same problem but the solution was to simply ingore it and go on. Don't try to sand it level until after several coats, just sand it enough to accept the next coat until there is sufficient build to level without sanding through, then you should be alright.

_________________
Tickle your guitar daily, and it'll tickle you back.

Thanks guys, it's good to know I'm not alone on this one. Have you guys ever done more than 8 coats? I ended up doing like 15 on this last one to build it up enough. Though, I did start sanding at 400 grit, still took a while to level though. Mayble I'll try starting at a lighter grit next time.

I have also started at 400 but will start 800 up next time. I too have had sand thru. I think it is because the water base is actually quite thin in its consistency.

_________________
Greg
http://garibaldiinstruments.com/

Hey welcome Bennie! Still fighting KTM9 battle!
While I have no real experience with this finish the advice sounds good.
Finish just has a way of racking your nerves. Keep at it my friend.
By the way, Ben and I shared shop space for a while before he moved out
west; he's a good man to have on board.

Louis

_________________
- Louis Freilicher

Oh No! Not another learning experience!

[QUOTE=Bennieside] Thanks guys, it's good to know I'm not alone on this one. Have you guys ever done more than 8 coats? I ended up doing like 15 on this last one to build it up enough. Though, I did start sanding at 400 grit, still took a while to level though. Mayble I'll try starting at a lighter grit next time. [/QUOTE]

When you start letting the first coats build, you will find that you use less coats overall. Mind you, you still have to sand every coat that you let dry over an hour but just enough to give the next one a bite. Don't level until you start your third days spraying asumming 2 to 3 coats per day. I usually allow 45 or so minute between coats, that way your not sanding at all between coats. I've actually gone back to nitro but only because it seems that's what my clients want and it's much easier to fix things and get the finish I like.

_________________
Tickle your guitar daily, and it'll tickle you back.

Ben, I just checked out your site and it looks like you and the Shiftless Rounders have been very busy this year. Let me know if you ever get out to the Sacramento area of California and I'll come see you play.
Take a moment guys, and check out Bens work and music it's great stuff.John How39065.2003703704

_________________
Tickle your guitar daily, and it'll tickle you back.

I found warming the guitar and the KTM9 before applying helped it flow out. Not perfect but much better.A bucket of warm water to heat the KTM and a couple of heat lamps supervised 2+ feet away from the guitar is what I used. Try it on some scrap and see if it helps.

Are you thinning the KTM or spraying it straight out of the can. When I was using KTM I thinned it a bit following Mike Dolin's guidelines. That was helpful for me when it came to getting a flater finish. LMI had a link to Mike's instructions.

Or you could just switch to Nitro (which is what I ended up doing)

_________________
Josh House

Canadian Luthier Supply
http://www.canadianluthiersupply.com
https://www.facebook.com/canadianluthiersupply?ref=hl
House Guitars - Custom Built Acoustic Instruments.
http://www.houseguitars.com

First of all those that have said ignore the orange peel effect are correct. build your finish, cure, level sand and all will be well with the world. I have found that the amount of orange peel is a direct relation ship to the pressure, volume of media and what needle you use. I am having a lot less Orange peel with a .95mm needle that was was getting with the 1.4mm that came with my gun Some thin KTM9 with DA but I shoot straight. I have found that if I shoot wet enough not to orange peel a little that I run a risk of the coat sagging. So I live with a little orange peel.

Thanks for all the kind words.

John, thanks for checking out my websites, The Shiftless Rounders will be in Davis, CA at the Delta of Venus on Thursday March 15th, I think that's pretty close to Sacremento, anyway would love to meet you there (It's free or else I'd put you on the guest list). Also wondering John, how the carbon fiber neck support is working out on your parlor guitars. This is something I've been thinking about for my nylon strings as I make a bit thinner neck than is traditional (which my customers all have loved), and am making my own lightweight adjustable truss rods currently for these.      

Louis, thanks for turning me on to this forum, everyone has been so helpful.

Hesh, thanks for the kind welcome.

I think I'll try the smaller tip for my gun, as well as a bit of thinning (I have been spraying right out of the can). I'm leaving laquer behind because I don't have adequate ventilation/filtering and I live on the Puegot sound, and laquer fumes bother me and my housemates.

[QUOTE=Bennieside] Thanks for all the kind words.

John, thanks for checking out my websites, The Shiftless Rounders will be in Davis, CA at the Delta of Venus on Thursday March 15th, I think that's pretty close to Sacremento, anyway would love to meet you there (It's free or else I'd put you on the guest list). Also wondering John, how the carbon fiber neck support is working out on your parlor guitars. This is something I've been thinking about for my nylon strings as I make a bit thinner neck than is traditional (which my customers all have loved), and am making my own lightweight adjustable truss rods currently for these.      
[/QUOTE]

Cool, yeah Davis is about an hour from me so if you think of it, remind me as the time comes near but I'd love to go watch your show.
I really like just using carbon fiber. Since these are short scale 12 fretters, there hasn't been much movement at all. I level the fingerboard before fretting and after stringing up I get just the right amount of relief and so far it has stayed just that way. I use 2 3/16"x1/4" rods in each neck about an inch apart, embeded with epoxy.
Most nylon string guitars don't even have truss rods do they, so I'd say it'll work fine. I assume your just doing it because your necks are thinner.

_________________
Tickle your guitar daily, and it'll tickle you back.