I've been airbrushing for more than 20 years & use it on just about every project in one form or another, whether … its 1/35 scale models or 15mm little tanks.
We got to work on your definition of "little" tanks.
Unless of course you mean a tank that is 15mm long. Then yeah, we can use the term "little tanks".
Of course, the principal advantage of "little tanks" is "bigger tank units".
Which means that the painting techniques I use may not necessarily apply, both because, well, the techniques for painting smaller stuff might not apply the same way to larger stuff, and because the techniques that one chooses when faced with 15 or 20 tanks to paint in a day might not apply to the techniques one chooses when faced with only one or two tanks.
But, that said …
I have never used an airbrush. I know folks at micro armor scales who do. I'm not one of them. Don't know if I'd like it or not. But I don't (at least so far).
My approach is:
1 ) Prime in white with spray paint. I have tried other colors of primers (black, gray). I have used modelling specialist primers in the past. But now I go with generic auto store or hardware store white primers, like Rustoleum.
Leave in the sun to bake for an hour or so, turning the models at least once.
2 ) Spray the base coat. I like Tamiya ModelMaster enamels.
Leave in the sun to bake again. Ah, the joy of California weather.
3 ) If doing camo, this is a good time to do it. Also a good time to do national markings (I don't use decals -- not against 'em, just find 'em too fiddley at this scale). Most of my detailing paints are brush-applied acrylic hobby paints. I love(d) Poly-S, but now am resolved to switching over to Vallejo. Not a big fan of Tamiya Model Master acrylics, except for a select few colors. I have some enamels that I use mostly when I need to match the spray base coats for some reason.
4 ) Do a dark wash. I use oily black or perhaps very dark brown acrylic, diluted heavily with water. I use a pretty large brush (by my standards), and completely cover the tank in the wash. Then move on to the next tank. This is really nerve wracking. The whole bloody tank, that I spent so much time painting, is a big black blob. But just hang on for about 4 or 5 minutes… After I've blobbed the wash all over the third or fourth tank, I go back to the first with a big old brush, and start dabbing. Dab dab, squeeze the brush in a dry cloth. Dab dab dab. Squeeze again. Wash the brush if needed, squeeze it dry, and get dabbing. Let my paranoia get the best of me, and try to wick that nasty old wash off my pretty tank. I must save it! But don't take too long, 'cuz I got to save 3 more, so I only have 3 to 4 minutes for each.
5 ) Dry brush, using a lighter tone than the base coat. Sometimes it's a white or yellow mixed with the base, sometimes it's another color but in the same hue. Dry brush the whole thing.
6 ) Detailing. VERY small brush to do whatever I choose -- picks and shovels, tow cables, crew figures and hatches if I've put 'em in. Gun muzzles (always dab black on the bore of the gun!). Headlights. MGs. And tracks! Gun metal if the tank should have metal tracks, black if the tank should have rubber tracks. Some times armies painted metal tracks black (Germans tended to do this. But I don't build / collect Germans, so it's of little concern to me.).
7 ) One more wash of the tracks and running gear, using a rust color, not as heavily diluted as the black wash. Only a little blotting this time -- enough to push the wash into recesses, not enough to wick much of it away.
Put back in the sun to bake.
8 ) Spray with Testor's Dullcoat. Bake in the sun, spray again.
9 ) IF I'm going to use a fine-point pen for any of the marketings, now is the time. Made this mistake more than once. Paint before dullcoat = good. Ink before dullcoat = bad, very bad.
So some results:
A battery of US Army T19s to support my M3s in Tunisia.
This is an example of crew figures and national markings.
French tanks are fun for the camo. Here I've used a national roundel to identify the platoon commander. The red and white circles were painted. Then after the dullcoating, a blue ink pen was used to complete the tricolor. An extra dab of oily black wash was applied to the engine grills, and not wicked off as aggressively.
And a reminder that, at this scale, it is units, not elements, that count.
An interesting comparison to see the evolution of my techniques.
The ISU-152 in the back got white priming, Medium Green base coat, and detailing. A black wash was applied only to the engine grill.
The SU-152 in the front got the whole treatment I described above. Same white priming, same Medium Green spray base coat. But got the dark wash, the dab dab dab, and the dry brushing. Much impressed as I was with the results of white primer under the sprayed base coat -- a technique I fumbled around into on my own in the early/mid 1990s, I much prefer the results in front, from the approach I derived from my readings on various online fora in the mid-2000s, primarily an adaptation of Troy Ritter's approach (https://ritterkrieg.blogspot.com/).
Of course, no matter how much I like any one, keep in mind this is a batch technique.
That's how I manage. Adopt, adapt, or ignore at your discretion.
-Mark
(aka: Mk 1)
goes into repair mode when painted models are damaged in shipping.
