[NSRCA-discussion] paint

[Gray E Fowler]

Robert

Humidity is not a problem, dew point is. Since it is warm now in most 
places this should not be a problem.  The amount of reducer called out by 
the paint manufacturer has two purposes, 

1. Reduce the viscosity so a standard paint gun can atomize
2. Only reduce the viscosity barely enough as to meet EPA volatile organic 
emmision requirements 

The PPG "reducer" amounts allow the car painting guy to seriously "lay it 
on" with out fear of runs or overspray. Unfortunately laying it on an 
airplane increases weight. A thicker clear coat will not really protect 
your plane better than a thinner coat, so it is just weight. Adding more 
reducer (its really a blend of different solvents)  will allow for thinner 
coats, less overspray, but can increase runs. 

The reducer like I mentioned is a blend of solvents, and all of this 100% 
evaporates and has nothing to do with the urethane chemical reaction that 
cures the clearcoat. You can add as much reducer as you want without 
reprisal...except from the EPA, which I doubt will go after an individual 
pattern guy...but I could be wrong.  So once you are comfortable with 
increasing your local pollution level...add that 200% reducer!!!



Gray Fowler
Senior Principal Chemical Engineer
Radome and Composites Engineering
Raytheon



"Robert Mairs" <robertm at sssnet.com> 
Sent by: nsrca-discussion-bounces at lists.nsrca.org
07/12/2006 05:42 AM
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[NSRCA-discussion] paint






Couple of painting questions.

Weathers turned to crap around here again.  How much humidity is to humid 
to 
paint?

I've been reading where the jet guys are reducing they're clear coat to a 
200% ratio.  They think it's great.  Anybody tried this? 


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