Painting questions for the experts

First off, history. I use Nason metallic enamels that I have mixed at NAPA. I have had great luck in the past. I paint outside, yes outside!! I have a 26 gal air compressor and I use gravity fed guns. I use 3 part paint (paint, reducer and catalyst), and so far I love the results. My question concerns humidity. I did a google search and one result was from the Hotrod Forum,same question asked. The majority of the answers said humidity was not much of an issue with recent paint formulations. Remember I am using enamels not urethane. Advice given was to use a slow reducer. I do not clearcoat, just not interested in it. I use (The WetLook) catalyst and my rockets look like they are wet, even in the sun! With constant high humidity, does this advice sound sound? I have slow reducer, and was going to try it on a nose cone just as an experiment. Its 93% humidity here today. What surprised me is that some of the replies from the Hotrod forum said alot of guys like to paint in the rain,keeps dust down. I assume they are painting indoors though. Any and all advice will be welcome, thanks.

Yep, painting inside...

Depends on the formulation of the paint, and a slow reducer should definitely help. Lacquers were more susceptible to blushing from excess humidity due to the inherently "fast" evaporation of the lacquer thinner (since it's much "hotter" than solvents used for enamels). Just don't do your painting in direct sunlight or if you do, move the rocket into the shade after painting so the additional heat of sunlight doesn't burn the solvent off too fast... and of course, the hotter the day, the faster the solvent evaporates...

Got a moisture separator or filter on your gun?? You're much more likely to get moisture from your air compressor/lines than from the environment (unless your painting outside in the rain, but who'd do a thing like that??).

Later and good luck! OL JR

Ha. We dance in the streets here if the humidity goes above 20%, so I am zero help on the RH question.

On the painting outside though, actually I see no reason not to do it if it's pretty calm - we built a small booth in our garage, and if it's too confined, the aerosolized paint will slowly settle as paint "fur" on every surface. Including the rocket, which then has to be sanded. This happened when we had plastic on all five sides, like you see here:



When we left the "front" of the booth open, the problem disappeared. <shrugs> It's a learning experience!


All the best, james

Well I took a chance and painted a 7.5" Standard Arm today. Weather.com said humidity for my area was 73%. All I had was medium reducer and no cash to make a trip to the store. First time using a 2.0 valve, not sure I like it. I have used 1.4 in the past. Anyway everything looks great so far, the rocket will bake in my shop all week for Sci-power next weekend. I usually wet sand and put a second coat but I might skip that this time.

I'm a long way from any expert advice on this subject, but one thing I have learned is, Weather dot com, like any other weather site, readings are taken from the airports. That can vary tremendously within just a few miles. Our small plane airport is about 5 miles from here and I used to paint based on the online readings taken from there, and fowled up more paint jobs than I care to think about. Granted I use rattle cans most of the time unless NAPA mixes me some metallic for my airbrush. But I went to Lowe's and bought one of the indoor / outdoor digital thermo / hygrometers, and it's really accurate. I haven't spoiled a paint job since. I've seen humidity differences anywhere from 8 - 15% just from where I live and what the reading at the airport was.