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| KTM-9 ’pimples’ http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10102&t=8272 |
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| Author: | vandenboom [ Sat Sep 02, 2006 8:49 pm ] |
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I am at the finish stage for my first guitar and using KTM-9. I have read other threads saying it isn't hard enough, but I have pushed on regardless. I used a foam brush to apply it and am following Mike Doolan's detailed guidelines for the overall process. I am leaving it to cure for 2 weeks. It has been drying for over 8 days now at around 20 degrees C and 45-50% humidity. I am a bit concerned about lots of tiny 'pimples' over the surface. The instructions say to start with 1000-grit in the rubbing/polishing process, but I am wondering if I need to use something heavier to begin with to get rid of the pimples. I also have a couple of spots where the laquer went on a bit thick and it is cloudy/white. I think I will have to slice these off with a very sharp blade. Any suggestions on the above??? |
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| Author: | GregG [ Sat Sep 02, 2006 10:40 pm ] |
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I'm not sure about the cloudy areas, but I did use a more aggressive paper to remove the bumps/pimples, just be careful as it is really easy to sand through to the wood, then it is no fun at all. Greg |
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| Author: | JJ Donohue [ Sun Sep 03, 2006 12:30 am ] |
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I would start wet sanding lightly using 320 grit and progerss through each grit up to 12,000 Micro Mesh. This is from personal experience. Also...it goes a lot easier if you wait at least 2 weeks to allow it to cure out and get harder. |
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| Author: | Pete Licis [ Tue Sep 05, 2006 3:00 am ] |
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These are literally pimples (protrusions) and not dimples like burst bubbles? |
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| Author: | Don Williams [ Tue Sep 05, 2006 3:07 am ] |
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Anytime something goes on thick and is cloudy, you need to remove the excess material. More than likely, it's not going to be cured very well under there, and you're going to have issues. Brushing isn't the best method by any means for ktm-9. But if you're going to brush it, you will need to thin it enough to flow out and level itself better. You may have to touch up those areas... |
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| Author: | Michael Dale Payne [ Tue Sep 05, 2006 3:27 am ] |
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Don is right KTM9 can be brushed on but need tinned about 20% to brush well. the pimples you see are most likely where air bubbles rose to the surface if you did not have cloudy areas I would tel you to sand to level with 220-320-400, then polish out with 600-800-1000-1200 or 3200-3600-4000-6000-8000-12000 micromesh but since you do have a cloudy finish I would have to recommend that you remove all the finish and start over with KTM9 reduced by 20% if brushing. Grafted coatings I believe makes a reducer for KTM9. but I would think that "Distilled water" would work. You might call LMI to see if they carry the reducer. I don't see it on their web site. |
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| Author: | JBreault [ Tue Sep 05, 2006 4:47 am ] |
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Instaed of distilled water, I think that grain alcohol would work a little better. I know that is what Pat used when he padded on KTM9 and Doolin used it to thin the stuff when he sprayed it. |
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| Author: | Michael Dale Payne [ Tue Sep 05, 2006 5:17 am ] |
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I believe both will work the alcohol would flash off much faster, and there by be the better choice |
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| Author: | burbank [ Tue Sep 05, 2006 5:27 am ] |
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As Joe said, I used alcohol (denatured) and also with water, 50/50 to thin 20%. The padding process was more closely resembled FP than brushing, though. |
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| Author: | vandenboom [ Fri Sep 08, 2006 1:11 pm ] |
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Pat - what do you mean by FP? |
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| Author: | vandenboom [ Fri Sep 08, 2006 1:22 pm ] |
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I have to take notice of you guys because you have tried all the variations. There are instructions on the LMI site by John Greven on KTM-9 application which say that you don't need to thin when brushing - so that's why I didn't. Next time I will do it your way-though next time, I will probably spray. They are fine pimples, not dimples. The cloudiness is only in a couple of very small spots - generally on the binding. I will cut them away and do a touch up, then try your sanding sequence before I take the step of going back to square one, because, apart from the pimples which look like they will be dealt with by sanding, the rest of it looks good (to my "first guitar" eye). I had not heard of Micromesh until I saw another post of yours the other day - I got a hobby kit from an Australian supplier which should be enough to do one guitar. I could not find any other aussie suppliers - so will purchase direct from micro-surface next time. Thank you for your suggestions and insight. |
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| Author: | Michael Dale Payne [ Sat Sep 09, 2006 6:53 am ] |
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Yes it can be brushed straight out of the can, but IMO and I assume many others it goes on too thick for more than one coat a day. I would probably be fine where a thicker finish is required but on guitars I like to build the film thinner than I do on my jewelry boxes or furnisher FP is an abbreviation for French polish |
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| Author: | j.Brown [ Sun Sep 10, 2006 1:40 am ] |
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A foam brush is the best way to brush it on from what I've experienced. The bristle brush can put it on too thick. Thinning with DA or Water is better in any case. The foam brush seems to let it settle into itself better, too. -j. |
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