dodgy results!

Phil, you've nailed it again. It's real cold down here, I painted outside, the marks were a whitish haze (some were rings) and I probably didn't stir it enough. Is there any form of troubleshooting that you don't have an answer to?

I'll try stirring more thoroughly and at warmer times. Thanks to both of you.

. i use humbrol paints (all i use) and never have ANY trouble with them. i admit i never used the humbrol thinner though. you might want to see if you can get some oderless mineral spirits. i use it with my paints (just a couple of drops) and no issues!

It's hard to say without being able to see what's actually happened, but my first thoughts are:

1: Insufficient mixing of paint and thinner. After adding the thinner to the paint, stir very well before putting the thinned mixture into your paint jar/cup

2: Moisture contamination.

(A): Do you have a moisture trap on your compressor? If not, you could have moisture in your air line which is being deposited on your model.

(B): Condensation on the wet paint during or after application. It's pretty cold in South Australia at the moment.

(i) Condensation may form in the paint stream due to temperature drop caused by evaporation of thinner from the paint between the airbrush and the model.

(ii) Are you painting outside and then taking the still wet/semi wet painted parts into a warm house?

In either situation, you could be getting localised condensation on those parts, which may leave marks like you're describing. (Typically a whitish haze, sometimes specks, rings)

Note that (A) and (B) are not directly related and are separate issues.