Trouble with maintaining constant paint flow with Paasche H airbrush and a question about how to spray more crisp edges on camouflage

[Eaglecash867]

I tried airbrushing tank tracks (plastic links on their sprues) with dark iron Tamiya paint (thinned with X-20A yesterday) using a Master airbrush, and I had a pretty hard time getting the paint to adhere. The paint kept ‘sliding around’ on the surface of the pieces, getting shiny, but just not darkening. I had to make several passes and only fully depressing the trigger (discharging a ton of paint) really allowed the paint to really somewhat take. Even after using an entire small jar (10ml) of the dark iron paint, one can still see the dark yellow (original sprue color) on the pieces. I did not think it was necessary to prime sprue tanks tracks (because of their relatively small size), but maybe that was my first mistaken assumption?

I prime everything with decanted Tamiya Grey Surface Primer through my airbrush, which helps significantly with keeping paint from sliding around like you describe. But, that may not be the biggest problem you’re having. It sounds like you might be trying for complete coverage in one pass, which will also cause paint to slide around, even on a primed surface. What you want to do is make several passes with the airbrush (and this includes when you’re putting primer on the model), getting progressively closer to what you’re painting with each pass. This builds the paint coat up in several, extremely thin layers and the first layers give the subsequent layers something to sort of “join hands with” so you can get good coverage without blowing the paint you just put down off the model. It seems counter-intuitive, but a higher volume of paint isn’t the way to go for good coverage…the paint goes on too wet, and the air blast from the airbrush pushes it around on a surface it hasn’t had a chance to adhere to yet. In this case, less is more. That being said, I don’t build tanks so I don’t know this for sure, but its my understanding that track links in a lot of those kits are more of a vinyl, which presents unique challenges for getting paint to adhere to them. I’m sure the guys who do build tanks have good methods for dealing with that.

Secondly, maybe the fact that my narrow time window for airbrushing is just after sunup (about 7:00AM) and that the temperature was in the low to mid 40’s had something to do with the crummy results I got? I had planned to airbrush some camouflage using Tamiya paint and isopropyl alchohol later in this paitning session, but I decided not to try because I was thinking maybe the weather conditions were not suitable…

You’re definitely on the right track there. Temperatures that are too high or too low will have an effect on your painting results. If you use lower air pressure and lower paint volume, you’ll solve that problem as well, because you’ll be able to paint indoors. When I first got my Paasche H when I was 15 years old (the same one I use today at 51), the whole point of getting an airbrush for me was so I wouldn’t have to paint outside like I had to with rattle cans. Since day one I have always used a low-pressure, low-volume painting technique that results in nearly all of the paint going on the model instead of being scattered into the air in huge clouds like I have seen so many modelers on YouTube doing. When I have to hold a part with my fingers while airbrushing, I may get a tiny bit of overspray on my fingers…but that’s the extent of paint going places other than the model. That also results in very little odor that only lasts a few seconds. Tamiya paint is probably the most odor-free, MRP lacquer is second, and enamels are the worst (takes the solvents forever to evaporate).