I have my paint booth set up in my garage. Given, I still live in the south, but I'll still have temperatures in the 50's, dipping maybe into the upper 40's at night while I'm working.

I spray Tamiya and MM acrylics exclusively, typically thinner with Tamiya thinner and MM's thinner respectively, typically mixed with some extra iso. alcohol to thin it out further and deal with the humid conditions I'm normally accustomed to.

Cold air is inherently very dry, so my logic says to not use the alcohol. Any other ideas? Any recommendations on how to adjust airbrush settings, paint mixture (thinner, thicker), etc would be appreciated.

Jesse;

If, as you have indicated, you are working in the 40's and up, I would not expect much issue with acrylic paint viscosities increasing.

As long as the viscosity is like that of "milk", you should, I believe, be able to spray with confidence (of course, if your fingers were like mine, your ability to actually control your airbrush might be, shall we say, a little shaky... but that's me. Brrrr! I think I'm a fair-weather warm room type of modeler!).

By all means, thin with the isopropyl, if that is what you are generally used to and comfy with (others may prefer other thinning agents- I'm an "isopropyl guy").

As to the humidity ("dryness") effect of the air at mid-40s degree F.... You are still well above freezing (32) and the air can still hold substantial moisture. Just ask anyone setting out into the foggy chill night! The term "bone-chilling cold and damp" comes to mind.

As for Alcohol... it evaporates just as water does, but with a lower boiling point (and also a much lower freezing point). Cooler temps will slow its evaporation - this will mean slower drying of paints, as compared to shooting the same mix at warmer temps. You should be perfectly "safe" thinning with alcohol at your lower temps. Now, if you were speaking of sub-freezing and lower temps, you could run into other issues involving various ingredients in the paint...

Basically, if you are comfy with thinning with isopropyl alky at room temps, as am I, you should be at least as comfy with alky in the cool 40s. And you'll have less vapour - inhalation risk!

But, of course, experiment - Try it out on the bottom of a kit and see what does happen in your particular circumstances!

Cheers!

Bob