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I'm currently using EM6000 for my guitars now, but I just sprayed a guitar with some left-over cans of Stew-Mac solvent-based lacquer (the spray cans). I have a couple of questions that someone may be able to offer some insight on.

1) If I ended up with .008" of finish just after spraying, is there a way to estimate roughly how much the finish will shrink as it cures over a month's time, and what final thickness I'll end up with.

2) I'm also wondering... it's not real convenient to leave the guitar in my garage for an extended period of time while it cures (too difficult to heat / maintain a constant temp). Can I safely hang it inside my house after a couple of days, i.e. will most of the gassing-off occur in that time, enough so that it's not too bad (for our health) to have it 'hanging around the house'? (winter is not an easy time to do finish work)

Thanks for any insights...
Ken

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Ken Mitchell
Durham, NC

Define just after spraying ??? Most solvent lacquers will gas off most of their wet thickness in a short matter of time ... if the wet coat is say 5 mil, and you have 20% solids lacquer, then you will end up with about 1 mil after maybe a half hour at most. Once you can touch the dired lacquer, which usually takes only takes a few minutes, its mostly gassed off. You will still get odor for a couple days, but the thickness isnt changing much at all. If you measure 8 mil after its dried a couple days, then the final cured thickness will be pretty close to that.

best way to find out for sure is to try on some scrap .. and then measure

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

I would be surprised if rattle can lacquer is more than 10% solids, but I haven't used the Stew Mac stuff.

OK, the finish on the top measured 8 mil after a day or so. I guess the final thickness will be a little less than that.

As for the danger of breathing it after a few days, is it just mostly a question of odor, and not really 'dangerous' per se? That's what my intuition tells me.

Thanks...
Ken

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Ken Mitchell
Durham, NC

I wouldn't want to breathe the stuff. But danger is in the eye of the beholder I guess....

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Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

Ken, it's just a odor by that point. It is not concentrated enough to cause illness, unless you're one of these people who are extremely sensitive to certain chemicals (like peanuts, household cleaners, etc). They are the exception, not the rule.

??? And what causes the odor? Could it be VOCs? Sure, the concentration is no where near as bad as when the finish is still wet, but they are still there. And this is not an allergenic concern. VOCs are hazardous due to toxic and carcinogenic properties and you should not expose your family to any more than you have to. If necessary, you could hang the guitar in a bathroom with the exhaust fan on for at least 72 hours.

Hi Barry, just out of curiousity, what componds in Nitro lacquer are known carginogens?

How about solvents of the Benzine variety?
http://www.ncbi.nlm.nih.gov/pubmed/3053447

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Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

VOC's also cause nerve and brain damage.

I just read about them in my Anatomy and Physiology class.

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Old growth, shmold growth!

OK, I took the advice and warnings to heart... I left the guitar in my garage for about 72 hours, before bringing it into the house.

The reason I want to bring it inside the house ASAP is that it's hard for me to control the temp in the garage, where I spray my guitars. I have a kerosene heater, and some small electric ones, and an exhaust fan. And the reason I'm super careful about the temp is that this is the SECOND time I've shot this guitar. The first time, it got some serious cracks in the finish around the bridge patch area, and I had to take the top all the way back down to bare wood and start over

All seems relatively fine this time, though I did get a little cracking on one side of the bridge area, about 3/4" long. Hazards of shooting in the winter

Ken

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Ken Mitchell
Durham, NC

These may be related to humidity levels more so than temp.

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Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/