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Hello everyone...it has been a while since my last visit. I sprayed KTM on my second guitar about two years ago unsuccessfully. I am past the disappointment and would now like to complete the guitar. I am thinking of first attempting to rub out what I have.....there are several runs and some are big/tall. What is the best way to rub out runs?

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Guitars...One's too many...Twenty is not enough.

I will assume you are talking about KTM-9. Don't worry about the runs and uneven surface, as long as the paint is thick enough you have to view the finish as only a starting place. I use a cabinet scraper to cut off the runs, I've also used a single edge razor blade with the edge "turned". Afterwards I level sand with 1000 wet or dry used wet. Carefully sand so you don't go all the way through. Buff with 3M Perfect-it 3000, Menzera, or Meguires. You will amazed!
You have to view the paint as it is now, as being only a starting point. Work with it some more, all of the good finishes require some additional work to get an acceptable finish. Talk to the AUTOMOBILE paint store people, they know what they're talking about...........
Good luck,
Mikey

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

Thanks mhammond. I looked at it yesterday...it is a mess. I am going to sand it down. Can I apply shellac over KTM-9?

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Guitars...One's too many...Twenty is not enough.

Shellac is often called a "barrier coat". Here's a bit about that: http://www.woodweb.com/knowledge_base/B ... thane.html

Although I haven't specifically tried what your asking about the KTM...I think yes.

Instead of taking it all off, why don't you scrape the runs flush, level sand the whole thing and shoot a few more coats of KTM-9, being careful to not have runs. Then level and polish as normal?? Finishing has a pretty steep learning curve. I'm not looking forward to the day I switch from brush to spray, as I'm getting pretty good results, and don't want to have to relearn a system.

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Rob

Well.....I tried that multiple times. This is my second guitar....I French polished the first one and it turned out great...but it took forever. I decided that I would try spraying KTM-9 on my second guitar. I have a very nice gun and could not get KTM-9 to spray....I tried various techniques...and failed every time....either got runs or a sandy feel when dry. The rosewood was more problematic than the mahogany. In short, I will never go down that path again.

So, I am back the dreaded French polish which I know I can get to work. In the future, I may try using Minwax wipe on polyurethane.....I used this on a bar top and stair spindles....the stuff goes on thin, is easy and beautiful....not sure if poly is appropriate for classical guitars though.

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Guitars...One's too many...Twenty is not enough.

It sounds like your problem is more with your spraying technique than anything else and it is almost impossible to teach that over the internet. I am very much a novice at finishing but have switched to KTM-9 (after first using nitro, then StewMac water based) and it will be my finish on everything in the future. I used Z-poxy to pore fill, then shot the KTM-9 directly over it.

I use a small detail gun (what an auto finisher would call a "jamb" gun) with a cheap little home compressor. Water filter in the line and pressure set about 45 psi, practice spraying medium coats that look wet when they go on, but not so much that it runs. I clean my gun with denatured alcohol which I leave in the cup - for the next coat first mist a little alcohol on, dump the cup out and fill with the KTM and shoot - the mist coat makes the previous coat slightly tacky and the is supposed to make them melt together. If you get a run or a little orange peel just scrape and sand to about 320, then shoot the next coats.

Get enought coats on (15 to 20 or more) before you do the final color sanding and buffing. As you know, you can also brush KTM-9 - you just might have to do a little more leveling. There pretty good instructions for KTM-9 at LMI and here is a picture of the first one that I used it on - don't give up on it so easily.

Thanks everyone,

I decided today to try and rub out the back of the guitar before I went ahead and stripped and french polished....what do I have to lose! After an hour, I am pleased with the results and I think I will continue and rub the guitar out and finish it instead of stripping and french polishing.

Here is what I did today on just the guitar back, which had a little orange peel and a sandy feel. I wet sanded with water, 400 then 600 then 1500. I then followed up with 4F and then Rottenstone. Lastly, I applied Mcguiers #7. When I look at the finish, I can see light scratches....any advise?

Thanks,
Doug

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Guitars...One's too many...Twenty is not enough.

Glad you are going to try the KTM. My guess is that you have scratches from the 400 and 600 that weren't taken out by the 1500. I try to make it a point to not skip any grits - 400, 600, 800, 1200, 1500, then I use SM medium and fine compounds on a buffing wheel.

Good luck