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Last week we had some discussion on brushing on KTM9 and as typical for me I suggest using a 20% cut on the KTM9 and a high end China bristle brush for application.

I forget whom, but someone said they brush on uncut with a foam brush and got good results, so I did a couple experiments this week end.

I use 4 scraps of mahogany all pore filled with zpoxy and a seal coat of shellac followed by 3 coats of KTM9.

1st was uncut with a foam brush. The first coat went on too thick for my tastes with quite a bit of air bubbles that ended up being pinhead voids after flow out. The second and third coats were the same.

2nd was uncut with a high end China bristle brush. It to went on too thich but no air voids but I did have some excessive ridging after flow out. Same thing on all three coats.

3rd was 20% cut with DA applied with a foam brush. I got less air bubbles but still quite a few, a more level flow out on the first coat. So on the next two coats I really tried to lighten the touch to eliminate air voids but actually seam to get more when I did. It seems to me that if you load the foam brush and turn till it stops dripping that it will not flow off the foam with out needing to add some light pressure to the stoke and when you add the pressure you get air bubbles in the KTM9.

4th was 20% cut with DA applied with a high end China bristle brush. This flowed off the brush nice, not to thich and just a little ridging that flowed out to level in about 3 min. All three coats went well.

So in conclusion either I am using a bad technique for foam brush application or as I suspected a properly thinned cut of KTM9 flow off better from a good china bristle brush with out air void better than foam.

That said you can get an equal quality finish from either but to me it looks like more leveling work with a foam brush

Is that adding 20% by volume of DA?
So, if I had an 8 oz. cup of KTM-9, I would add 1.6 oz., right?
I've used a foam brush with great success on my last 2 guitars and had very little bubbling and great leveling, but I'll give the bristle and thinning a try.
Thanks for the experiment.
-j.

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“If God dwells inside us like some people say, I sure hope He likes enchiladas, because that's what He's getting”
-jack handy

J. Like I said I may not be using the foam brush correctly. I used the basic lacquer brush stroke load the brush tun in over the containment till it stops dripping, glide on the surface allowing the media to flow off the brush applying almost no pressure to the brush. When I do this with foam it tracks out meaning gaps in the flow from off the brush, before I can get to the end unless I add a bit of pressure to the foam. Then when I do this I get air voids.


Yes 20% DA by volume. I actually did a fifth piece with 30% by volume Just to see how thin I could put it on and all seemed well but i would feel better with Just 20%.MichaelP38978.5428356482

Michael,
I brush on about 5 coats, level and then spray on about 3-4 more before final polish. I use foam brushes, but I'm not all that particular. I tried KTM9 and did not like it. I switched to CrystaLac. The Super Premium comes in a ready to spray formulation that seems to brush on nice for me. I have only used their satin, but will do


http://www.mcfeelys.com/product.asp?pid=CLP-0900my next 2 in gloss.

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"An adventure is only an inconvenience rightly considered. An inconvenience is an adventure wrongly considered." G. K. Chesterton.

I have no issues with KTM 9, I have been using it since ktm4 was reformulated. I normally spray and have brushed with 20% cut and CB brush many times on small repairs. However some one , and it may have been J. said they were using it with foam brush uncut and that was what drove the experiment. I actually knew going in that for me 20% cut and a china bristle brush worked well.MichaelP38978.5542013889

Just for someone that has never used a China bristle brush with a lacquer before. If the brush is not properly prepared you will have some shedding. I prep by tapping the new dry brush on my fore arm to shed all loose hairs. Then fully dampen with distilled water a rap in Kraft paper over night as you would store any brush to maintain the bristles shape. The next day I tap the brush on my fore arm again to remove any stray hairs and away I go. On a high end China bristle brush this should remove any shedding. On a cheap China bristle brush you may always have shedding issues. I do not recommend combing as this may cause more shedding than not combing, though I have heard of this being done.

Very helpful, Michael. Thank you.
-j.

_________________
“If God dwells inside us like some people say, I sure hope He likes enchiladas, because that's what He's getting”
-jack handy

I too have had bubbles problem brushing KTM-9. They were so bad I gave up. However, Pete Licis had good results using a foam brush and describes it
here: