longevity of paint mixed for airbrush use

  Try to mix only what you need at a time.Generally, I try to meter out paint using glass eye droppers and use (usually) a 50 :50 ratio of paint to thinner. I use the eye dropper to mix the paint and then drizzle some down the inside of the color cup. If it has a milk like tendency I am good to go. It also doesn't hurt to have some spare plastic or sprue around to test the paint consistency against..just my two cents..

Claude

Thanks I guess I better get painting.

Bill

It is generally not recommended that you thin & mix paint and hold it for a period of time.   Once you mix in the thinner the "curing" process begins and you will likely end up with a gooey mess of pigment in the bottle.  The time varies according to several environmental factors -- your milage may vary.

You can mix colors and hold them -- just don't add the thinner until ready to use.