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I have a compressor, and a small spray gun, but I haven't quite gotten set up for spraying finishes, either solvent or water based. Up until recently, I've been using Stew-Mac's aeorsol cans of clear coat, and that worked OK, but it's hard and very time consuming to get a decent build of lacquer (with a small exhaust fan / makeshift spray area). Just recently, I tried brushing on Stew-Mac's water based lacquer (essentially Target EM6000, correct?), and the one guitar that I've finished that way turned out reasonably well. It's a very low odor solution, not too difficult - but still quite time comsuming, and clean up is very easy.

So my first question is, is it possible to brush on solvent based lacquers like McFaddens or Behlen's as well? Perhaps with an appropriate amount of retarder? And ventilation... Would it flow on about as well as the water based stuff?

My second question is will a water based lacquer burn in and adhere to a solvent based lacquer? (My inclination is to think that the answer to this is 'NO').

Thanks for any input,

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Ken Mitchell
Durham, NC

Well .. have never tried to brush either of those products ... likely would need the retarder to slow the flash, and get it to level, oitherwise you will be sanding a bunch of brush lines forever. As well, it wil be tough to control film thickness this way.

Burn in from water/nitro .. I doubt it highly. Water will just sit on the nitro.

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Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

If you already have a compressor and spray gun, then spray the lacquer. You will get much better results than trying to brush it.

Finishing in guitar work is a very time consuming process no matter what. Spraying with a proper setup is infinitely better than brushing. If you're going to spray lacquer though, you really should have an explosion proof set-up for safety's sake. Also, even though the fumes from waterbornes aren't as noticeable, they are still toxic. The fact that they aren't as obnoxious may make them even more hazardous. You should use good ventilation with anything you spray. The real advantage of waterborne is that you don't have to be explosion proof, but you still need ventilation. Of course clean-up is easier also.

Waterborne will not burn-in to nitro although it may adhere well enough if you scuff up the nitro. You would have to test it. Another option would be to seal the nitro with a good sealer and then apply waterborne. Just know that you are really experimenting at this point.

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Randy Muth
RS Muth Guitars Website
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Randy, what you suggest may work for my situation. I retopped a guitar (it's just a 'home' guitar, not for sale), so the top is bare wood, sealed with shellac. I feathered in to the sides around the top binding, sealed any exposed wood with shellac, scuffed up the whole side area, back to the edge of the back binding. The back surface is fine, and hasn't been touched.

So in my situation, if I follow your suggestion, I may be able to blend in the two lacquers back at the rear edge?

That would be great. I'd like to finish this guitar out with water based, if possible.

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Ken Mitchell
Durham, NC

Ken, I think there is a good chance it will work, but no guarantees. Just make sure you provide some bite where the edges meet. P800 grit is enough. Also, you will probably see where the two finishes meet up, but if it is on the binding it may be acceptable to you. Finally, if you use KTM-SV, just make sure any oily woods that you may or may not be using for your rosette are well sealed with MULTIPLE coats of shellac. I talked about this in another thread. Personally, I use rosewood sealer.

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Randy Muth
RS Muth Guitars Website
RS Muth Guitars Blog
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Tony, Barry, Randy... thanks for your input!

I'm going to give this a try.

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Ken Mitchell
Durham, NC

"I tried brushing on Stew-Mac's water based lacquer (essentially Target EM6000, correct?)"

The answer to this question is; Nope Stew Mac ColorTone WB is Target's USL not Target's EM6000

Mike,

Target doesn't sell USL anymore. EM6000 is essentially a slightly tweaked reformulation of USL. If StewMac is restocking then what they are getting is EM6000

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Randy Muth
RS Muth Guitars Website
RS Muth Guitars Blog
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this may be the case, but I know up untill a very short time ago and historicly it has been USL. I just would not assume that because Target is obsoleting USL that what you get as Stewmac colortone has swithced over yet. Would be good to comfirm before assuming.

Mike,

I'm not assuming anything and I thought I implied that their current stock may still be USL. What you need to know is that there is almost no difference between USL and EM6000. Target is just consolidating their product line since there was lot of redundancy built into it for marketing purposes. I've worked with Target products for six years and have tried every product they offer. USL and EM6000 were offered concurrently and when I asked Jeff Weiss what the difference was between them he told me they were essentially the same. EM6000 was formulated with slightly less solids to better facilitate spraying (read thinned out).

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Randy Muth
RS Muth Guitars Website
RS Muth Guitars Blog
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One of the finishing books I read (can't put my finger on it at the moment...maybe Understanding Wood Finishing) says not to apply water borne over nitro. Nitro off-gasses solvents for years and suppposedly the gasses can't penetrate the water borne and that causes problems.

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http://www.chassonguitars.com

Kent,

Finishes can definitely be quirky and I wouldn't doubt that that may be the case. I actually have that book, but I haven't checked it. But you also have to be careful with generalizations. Once the solvent evaporates (water and other cosolvents) your left with the resin and perhaps some other additives left on the work piece. It doesn't matter per say that the carrier vehicle was water with the exception that it will affect the quality of the film formation. Having said that, when that book was written pretty much all, if not all the wateborne finishes used an acrylic resin. It may be that off gassing from nitro messed with acrylics. KTM-SV and EM2000 do not have acrylic resins, so all bets are off. Off gassing from nitro may or may not affect it. KTM-SV and EM2000 are the most atypical waterbornes you will encounter. They really behave a lot like solvent based varnish except that they dry very quickly and coats will burn into previously applied coats within a certain time window. In fact they don't even smell like other waterborne finishes. Acrylic based waterbornes have an ammonia smell just like a quality acrylic paint. These finishes smell like an oil based paint.

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Randy Muth
RS Muth Guitars Website
RS Muth Guitars Blog
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Mike have you heard or have experience with using this with hvlp? I am sure you have done this (shedule info), but some of us were in a thread about using em6000, what schedule do you use, and what sealers or fills etc? I have been using Z poxy, any thoughts on that? I seen in the forum about Stew Mac using this now or will as restock. Also some questioned hardness and sanding wet or dry, water or mineral spirits, any other information would be great. Really thinking of going to this for several reasons, so any information would be great.