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Since I'm completing 2 guitars in parallel, I thought I'd compare the 2 methods.

Brushing: I prepped the top surface with shellac and the B/S and neck Z-Poxy followed by shellac. I sanded with 400 grit prior to applying KTM-9 full strength. Using a 2" foam brush I applyed the finish trying to go as slow and smooth. My technique sucks because the coats were not pretty. Bubbles appeared on the surface and runs happened. I applied 4 coats about 1 hour apart. After a day I level sanded and everything became smooth. At this stage (after 1 day) it doesn't powder well but it smooths out fine. I then applied 3 more coats in the same manner and let it sit for 2 weeks.

Spraying: Prepping was identical to the brushed guitar. I use a cheap $100 HVLP sprayer I bought from Rockler. I used the KTM-9 straight from the can and it sprayed beautifully...4 coats at 1 hour intervals. I cleaned (rinsed) the nozzle each time and it performed well on subsequent coats. Level sanding after 4 coats went much better than brushing since the surface was significantly more uniform. 3 more coats and I let it sit for 2 weeks before wet sanding.

For the wet sanding process, I started with 400 through 2000 and then Micromesh from 4,000-6,000-8,000-12,000. After 6 hours of hand sanding on the brushed guitar and 4 hours on the sprayed one, I buffed on 14" wheels with Menzerna Fine and Extra Fine. I am very impressed with the results but the finish is still soft. Time will tell as to whether it hardens close to Nitro. The color is warm with no hint of blue.

Conclusions:
...Spraying made life a lot easier, although there is no difference in the final appearance. I'll be able to compare the final thicknesses once I remove the finish for the bridges and FB gluing operations.
...Comparing the look of the KTM-9 vs. my last effort with USL-9000, I'm much happier with the KTM results. I had blotching with the 9000 and I found the KTM-9 warmer in its appearance.
...I'll use KTM-9 again.    

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

JJ, where is our first look? We need picturesJohn How38567.4933217593

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

JJ,

I have yet to finish a guitar with KTM-9, but I've done quite a bit of testing using scrap of all sorts of stuff. I find it interesting that you say after one day the KTM didn't powder well on sanding. I found that it powdered fine after THREE MINUTES when using IR heat to help the drying process along, and probably five to ten minutes with just air drying.

My application was with a foam brush used in a way which I think puts on a coat considerably thinner than I envision straight brushing would. Because you had trouble with powdering after a whole day, I'm guessing that your coats may have been subsantially thicker than mine, and may not have received enough drying time with an hour between coats.

By the way, if I ever complete construction (Yes, Bruce D, and Don W, not done yet, but really getting close!), the instrument WILL be receiving a KTM-9 finish, since that seemed to be a fine finish in my tests. Compared to PSL, overall it's very similar, but I understand the KTM may have an edge on hardness/durability.

Padding is another method that seemed to work well with KTM-9, albeit a bit slow. In a test designed specifially for determining finish thickness, I found that 10 of my coats equalled 1 mil of dried finish.Pete Licis38567.5254513889

John...no pics before I have them singing! This was just an interim report. Besides, I need to get a photo studio setup now that you've raised the bar for posted pics. Perhaps in another 2-3 weeks or so.

Pete...good info and feedback on the cure time. My effort was dried in a rather cold...68* and 40% basement shop. I may use IR heat next time.

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

First of All, was that THE PETE LICIS doing that posting? Wow.

Secondly, Pete, I'm beginning to change my thinking on completing instruments. It matters not how many you complete, but how many you have started!

Dear Lord, I'm the world's worst procrastinator, but I love starting new ones. Anyone got more than thirteen in the works?

Congrats guys, pics, we need pics.

[QUOTE=Dickey]I'm beginning to change my thinking on completing instruments. It matters not how many you complete, but how many you have started!
QUOTE]

Speaking of starting guitars Bruce, has the all rosewod goten anywhere? If so we need pics

[QUOTE=Dickey] First of All, was that THE PETE LICIS doing that posting? Wow.[/QUOTE]
Yes, Bruce, that WAS I - the ONE AND ONLY. Heaven forbid there be others around!


[QUOTE=Dickey]Secondly, Pete, I'm beginning to change my thinking on completing instruments. It matters not how many you complete, but how many you have started![/QUOTE]
Let me tell you - I've already started the next several ... mentally that is. Yeah, coming to think of it, one of those is nearly complete!


[QUOTE=Dickey]Dear Lord, I'm the world's worst procrastinator, but I love starting new ones. [/QUOTE]
Luckily, procrastination isn't my problem - it's lack of serious consecutive time basically. For instance, for the last few months I haven't really set foot in my shop because of a huge crunch (including travel) for work. But I freely admit, on those days that I'm too beat after work to head into the shop, I do just LOVE to sit around and dream up future instruments. And I may have a couple of doozies coming.



[QUOTE=Dickey]Congrats guys, pics, we need pics.[/QUOTE]
Ya' know, Bruce it's probably time for me to post a little update. It usually doesn't occur to me to post updates on my progress because, well ... frankly, no one would remember the previous update ... unless they had a really good memory

Grin, you guys! Okay, I had it coming. Michael, as I PM'd you, no the rosewood flitch-matched guitar is still a vision. The woods are on the build side of the shop, rather than the storage side.

UPDATE us Pete, shucks, I forgot what happened yesterday already. Did we hijack this thread or what?

As Yoda would say, "Hijacked it is!"

But I'd still like to hear more about KTM-9 experiences.

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

I'm trying to brush on KTM-9 now and it is not going well. I know that it is my brushing techniques. I say techniques because I've tried them all. None of them work. I get HUGE brush marks and bubbles.

The technique that I've tried the most is to use a good quality foam brush. I dip the brush into the finsih and then try to lightly touch it to the serface of the board. I move very slowly allowing the finsih to flow out of the brush. What happens is that there are ridges in the finsh that don't level. There are bubbles too. The bubbles are worse if I apply more pressure but never completely go away. If I apply too little pressure, the finish doesn't flow out in some places and I get dry streaks. If I use too much finsh in the brush, I get blue-white streaks. I can get ridges, bubbles, dry streaks and blue streaks in the same bush stroke. I've tried bristle brushes as well and the dumped finish on at the begining and dried out after moving about 5 inches.

Going over previous brushs make things worse. I've gone with full strength and various levels of thinning from using a slightly damp brush to 50/50 water/finish and everything in between.

So I decided to let the finsh be lumpy and sand it smooth. This was working OK but I had to use some pretty agressive sand paper and sanded through the finish. Since I intended to add more coats, I didn't worry about it too much. But, I have a very thin layer of SystemIII to bring out the grain on the top and I sanded through that as well. The sand through areas are visible under the next coat of finish.

I'm sanding the stuff off tomorrow and French polishing it. With french polish you can fix spots that don't look right without having to redo a whole surface.

In summary this has not been a pleasent experiance.
sigh. I don't have room in my shop for compressor so I'm looking at a turbine HVLP. Maybe I'll be able to figure out how to spray the stuff on.

This is not an inditement of KTM-9, however, I've had the same problems with PSL and any other lacquer or water based that I've tried. What I'd really like to know is how does this stuff know when it is being applied to a guitar as opposed to a scrap board. I have the most beautiful set of finished scap boards you'll ever see. All of the various techniques that failed on the guitar itself worked wonderfully on the test pieces.

bubbles are caused by the open cell structure of the foam. The harder you press the more and bigger bubble you get. If I were using foam brushes I would use retarder to slow the set rate to allow the bubbles to disapate.

you should use allmost no pressure at all when brushing on a finish. To get an even coat the film must flow off the brush and not be pulled off.

You are going to get some ridging when brushing. most will level out during set up, but not all.

A high quaility China brisel brush will help. The flow out will be better and no bubbles. However these brushes run in the $20 range each. but make a big diff.

KTM9 is so forgiving when sprayed I would spray JMO

Mike...I feel your pain with the brushing experience. Your description sounds like my frustrations.

Consider that $100 HVLP sprayer the Rockler sells. It really worked for me. I use the smaller of the 2 tips supplied and I was able to spray effectively in no time at all. After getting the pattern and flow adjusted it worked like a charm...and I have had no previous experience except with rattle can lacquer.

I'm pleased with the KTM-9 results so far but I'm still waiting to evaluate long term durability, scratch resistance, etc. before making a final decision. I just hope I never have to go back to Nitro.

Good luck!

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

I see that Rockler HVLP unit is on sale right now for $79. John How38569.5331597222

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

[QUOTE=John How] I see that Rockler HVLP unit is on sale right now for $79. [/QUOTE]

YEP, but they are over sold and all orders are going on back order.

Mike, the first time I used KTM-9, I used a method that John Greven detailed in a GAL quarterly about 18 months ago. I put it on with an old cotton sock rolled up into a ball. I thinned the KTM 9 with isopropyl alcohol and distilled water as per Mike Doolin's recipe and put on about 20 coats about 5 minutes apart. Dip the applicator in distilled water and squeze out the excess between coats. If you keep a wet edge, there is very little sanding necessary.

20 coats sounds like alot but I measured the thickness at the bridge and it was around .005. This method worked alot better for me than the foam brush. If I didn't have spray equipment this is the way I'd do it.

I posted a picture a couple of weeks ago of a sapele guitar I used this method on. It should be in the archives.

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Jimmy Caldwell
http://www.caldwellguitars.com

[QUOTE=JJ Donohue] Mike...I feel your pain with the brushing experience. Your description sounds like my frustrations.

Consider that $100 HVLP sprayer the Rockler sells. It really worked for me. I use the smaller of the 2 tips supplied and I was able to spray effectively in no time at all. After getting the pattern and flow adjusted it worked like a charm...and I have had no previous experience except with rattle can lacquer.

I'm pleased with the KTM-9 results so far but I'm still waiting to evaluate long term durability, scratch resistance, etc. before making a final decision. I just hope I never have to go back to Nitro.

Good luck![/QUOTE]

Thanks for the report JJ. Looks like my Wagner will probably work out just fine. By the way, I haven't seen or used one but Harbor Freight has a HVLP sprayer for $49.

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Don Atwood
Arlington, VA

Here I am having trouble with my nitro finish and wishing I was using KTM 9. Then I read this and say to myself- "It will never end these finishing problems". Whew, I thought it was only me that makes mistakes and has to correct! Nitro is not so easy as well. I did my last guitar with KTM-4A and french polished it on, as John Greven explained in GAL article. It worked very well. Can I not do the same with KTM-9? I hope so, although I do have a dedicated waterbase gun. Is Everybody using shellac with epoxy or does it just sound like it? I am using an old guitar back to test shellac as compared to staight epoxy. I used shellac last guitar and it took along time for the finish to harden--maybe that was the KTM-4A. Anyway thanks for posting your test results of spray vs brush. Will try to post my results of the next guitar, hopefully in a month or so.

[QUOTE=Ron Priest] Nitro is not so easy as well. [/QUOTE] I used to think that. Like anything Ron, there are a few secrets, once known, make it a walk in the park.

Sylvan and a few others helped me through getting it to flow like molten glass, then buff smooth and reflective as a lake on a still morning. Clear and classy.

I've given up on KTM-9 for this guitar and I'm switching to french polish. I'm pretty sure I'm getting an HVLP turbine and when I do I'll try again.

The french polishing is going great. The end result is a bit soft but it can be fixed easily enough.

As I said in my earlier post, I don't think the problem is with KTM-9. Put a brush in my hands and I'm down right dangerous. To quote the old medicine man, "I did the dance and it didn't rain. Now what?"

I did try to put the stuff on with a fad as well but I thinned with water. I might try the alcohol and see how that works. I don't mind 20 coats 5 minutes apart. I've been working on this finish for three weeks and just sanded it all off yesterday.