You are currently viewing Kit Guitar Forum archives. To view the current forums go to www.KitGuitarsForum.com/board



Log-in
Register
Members


Problems with spraying KTM9
Author
Post
PJ

Total Topics: 12
Total Posts: 90
Hi guys - two problems here. I just finished first day of spraying KTM 9. Did 6 coats, I am spraying fairly thin layers. Had problems with orange peel at 30 psi, increased pressure to 40 psi, less orange peel, but finish still dries mat and a bit rough. Is this normal, or what am I doing wrong? Secondly, (and I suppose it's a bit late for a cure) I sanded through the epoxy when leveling, lighter wood underneath. Redid epoxy twice in an effort to darken those areas, without much success. Obviously the areas remain lighter under the finish. Tomorrow I spray the final 5 or 6 coats after leveling the coats I have just sprayed, so I suppose I will have to live with these lighter areas?

Sep 13, 09 | 10:43 am
Ken Cierp

Total Topics: 58
Total Posts: 2262
Others can correct me here becasue I do not use or recommend the Zpoxy stuff --- however normal filling procedure calls for all the pore filler "except for what's in the pores" be sanded off -- in other words down to bare wood. Not trying to be critcal here, but "maybe" saving some trouble for other builders.

Ken

Kenneth Michael Guitars est. 1978

Sep 13, 09 | 11:24 am
Ken Cierp

Total Topics: 58
Total Posts: 2262
More:

Mike Doolin not longer uses KTM-9 but here is what he had to say about using epoxy filler in his KTM-9 Schedule:

However, epoxy is not intended as a finish product, so it doesn't flow out well at all and tends to fish-eye. The solution to this is to scrape it on with a plastic card, a business card or a single-edge razor blade, leaving as little as possible on the surface. I spread the epoxy across the wood surface and immediately scrape off as much as I can. This is a critical point: scrape off as much epoxy as possible! Don't leave any on the surface, just scrape it away and it will remain behind in the pores. That way, you won't have to sand it level later. On the other hand, make sure to get some epoxy on every square inch of the wood surface, to ensure consistent color and adhesion under finish.

Ken

Kenneth Michael Guitars est. 1978


Sep 13, 09 | 11:37 am
PJ

Total Topics: 12
Total Posts: 90
I followed Doolin's advice, but still had to level, notwithstanding using credit card, scraping of everything, et al - probably just not enough experience with it. Hated working with the epoxy though - will use a different pore filler for next build.

Sep 13, 09 | 11:50 am
Ken Cierp

Total Topics: 58
Total Posts: 2262
Not to dwell, but my question to you is --- this again is for others --- did you "completely" sand the epoxy material off the surface down to bare wood? If not, it goes a long way in explaining your problem. And I agree, as I mentioned time and time again a complete, documented finishing system from one manufacturer is the best choice. There is no such thing as a manufacturer documented KTM-9 finishing "system". PJ I do hope this works out well for you.

Ken

Kenneth Michael Guitars est. 1978

Sep 13, 09 | 12:09 pm
PJ

Total Topics: 12
Total Posts: 90
Hi Ken - as far as I could tell I was down to bare wood, and what made me sure was the fact that after sanding that particular area, it was lighter than the rest. It looked like the pores were properly filled though. I thought another coat of epoxy would solve the problem, but it didn't. So I sanded the entire back again and again applied epoxy - same result. I finally decided to live with the lighter colored section and proceeded to spray the first coats of KTM9. Sure hope I don't get this type of problem with my next build.

Sep 13, 09 | 11:53 pm
PJ

Total Topics: 12
Total Posts: 90
My problems continue, and I am a bit lost. Did what is supposed to be the final coats today, no running or sagging, but finish is not smooth as I expected it to be. It has dried mat, with what I suppose is called 'orange peel' texture, albeit fine. What am I doing wrong or is this normal for a KTM9 finish? (before polishing and buffing, of course). Any help will be appreciated.

Sep 14, 09 | 7:39 am
Ken Hundley

Total Topics: 40
Total Posts: 2169
Orange peel is not matte.....orange peal is like an orange peal....bumpy. Matte is normal for ktm9, it doesn't flow like tru-oil, but dries as droplets that begin to congeal. Start your sanding process, but only sand enough with each grit to remove the marks from the previous grit. It will become a beautiful finish, but will take a year or longer to truy harden. It is easy to scratch at first, but will eventually get harder.

I too had a light spot in my Rosewood back. 3 Years later, you can't tell. The wood will oxidize. It may be noticeable if you look for it, but the uninitiated would think it is a natural characteristic of the wood.

Sep 14, 09 | 2:11 pm
PJ

Total Topics: 12
Total Posts: 90
Ken - best news I've had in a long time! I was considering sanding the back back to bare wood and starting over, but I guess I'll rather wait and see - can always do it later, I suppose. As for the rest of the guitar - guess I'll wait and see how it buffs out. I laid down roughly 13 coats, and with the practice sessions included used up more than half the quart of KTM even though I sprayed very thin.

Sep 14, 09 | 11:55 pm
Ken Hundley

Total Topics: 40
Total Posts: 2169
Thats the problem with spraying, unfortunately. There's enough to brush on 5 guitars, but spray on 2 if you are lucky. I still like the stuff, though.

Sep 15, 09 | 1:43 pm



You must be a registered and logged in member to post in this forum