Originally posted by BHP
My understanding of why rattle can paint blushes in high humidity is because the cooling of the compressed gas/paint exiting the can reaches the dewpoint. You are effectively making dew on you new, wet paint.
When you paint in air that has a lower dewpoint the cooled, expanded gas/paint does not form the dew because the temperature does not lower to the dewpoint.
I can't explain why Rustoleum didn't blush for you but I'd assume the atmospheric conditions were not same. All gases cool as their pressure is lowered just as they warm when compressed.
But the bottom line is, as always, do what works for you. I like Krylon myself.
O.K. first thing;No it was pretty much the same all the time......humid,humid,humid.That's not exagerating at all.Like I told someone else;since I don't have the luxury of a booth or anything like that then it's either switch paints or wait until it's low enough humidity to paint.The problem with that is that when the moisture is that low i'll be too busy fightin' off tha Polar bears to paint.Welcome to Va.! Anyone at NARAM this year?
Now secondly I'll just go ahead and post what was told to me by one Mr.Doug Sams before I make an even bigger fool of myself than I already am trying to explain it:
"As others have said, it's the relative humidity. When a
compressed gas is allowed to expand, it absorbs heat. In
a humid environment, condensation will form due to this
cooling effect, and that condensation will cloud your
paint giving you a dull finish. Hot solvent enamels such
as Krylon and Testors as well as lacquers tend to do this
more so - the hot solvents tend to evaporate more quickly
than regular oil-based enamels.
The hot solvents have the nice feature of quick drying,
but at the expense of a dull finish (when the humidity is
up). Get some RustOleum (regular, not Painter's Choice)
and your blushing problem should go away. I've also had
good luck with Boyd's, which appears to use a different
formulation than its sibling Testors.
I got a hygrometer for my garage a while back. Last night
it was pushing 70% RH, so I opted not shoot any paint at all.
50% RH is OK for RustOleum. I haven't determined the RH for
Krylon and Testors yet, but I'm gonna try some next time it
gets below 40% RH".
This makes perfect sense because all of my rocket building has usually gone on during the winter when the humidity was relatively low.Subsequently I've never had any problems with Krylon,either.Also,I too like it a bunch but it hasn't been diggin' me at all this summer.This is the first summer that I have had this much time to build.