Now that I am getting some practice airbrushing KlassKote again, I thought I would pass along some random notes. I will emphasize as always that I am not necessarily the world's expert on the stuff, I have learned some stuff over the years.
Mixing: You want to mix up your color and catalyst well ahead of time, stirring frequently, 15-30 minutes, to let it start reacting. It is not super-critical, but I never mix less than 10ccs of each using the small mixing cups, for give me enough volume that missing it by a cc or so is not the end of the world. Do all that chemistry class stuff, measure to the meniscus, etc. Using more "part b"/"hardener" will not make it go off faster, missing it either way will make it less likely to cure properly. The 15 minutes is for the regular paint and the "slow" primer. The "fast" primer tells you not to do that, they are right, mix it (thoroughly) and then use it right away,
Thinning: The instructions say is is safe to use up to 10-15% reducer (per mixed volume). It is utterly inconceivable, it is far too thick to even imagine spraying it that way. 10% thinner, and you might do better with a spatula, it is FAR too thick to spray through an airbrush or any of the typical detail guns. Different colors vary, so you will have to experiment, but 1:1:1 is usually about right, or 50% per mixed volume. It's thicker than any K&B Superpoxy I have used. The problem with more thinner is "solvent trapping", where the epoxy part cures before all the thinner evaporates. This is not a problem for any of my experiences *spraying* it, the paint covers so well that you use only a tiny amount and the film thickness is nearly nothing, so at least the "slow" thinner (#500) will have no problem. "Fast" (#550) should be even better, but I have only used that with K&B, not KlassKote. Thin it until it flows out, don't worry about the volume.
Spraying: Most of the solid colors cover *very very well*, vastly better than any dope I have used. You need very little of it to make the colors solid. That's why it is so light. A few colors *do not* cover that well, "Deep Red", for example, covers poorly, while "Bright Red" covers very well. The white covers better than most white, good enough that I don't usually use a blocking coat, although it might be a good idea. As always, put on just enough.
Actually spraying with an airbrush, it can go on with a bit of orange peel and still flow out. It is not a fast-drying paint, it will flatten itself out very well. It also brushes very well and levels out brush strokes much better than most other model paint.
I use an internal-mix gun, the usual Paasche VL, with the #5 aircap, needle, etc.
Clean up: Just spray some thinner until it comes out clear. And then, the next day, throw it away and get a new one, because it is completely locked up. You must disassemble the brush/gun and clean each part that comes in contact with paint, and for an internal-mix gun, *remove the needle and clean it, clean the paint path through the gun very carefully, and leave the needle loose and separate from the gun, because even if you leave even a little bit of paint in it, it will be locked up when you grab it the next time. I usually remove the needle and store it separately. Roll up the tip of a paper towel to get into the spigot that you push the paint cup into, clean that first, then dip the entire front end in lacquer thinner over an over until it is clear. Then get the real thinner, and repeat it. I also use a small bottle brush to come in from the rear through the needle seal, clean it again.
I suspected this would be a problem, so I was very careful, but even I have had a few close calls, and one damaged nozzle where I had to replace the entire #5 set.
The real thinner works far better for cleaning than any variety of lacquer thinner, but I use lacquer thinner to get most of it, then finish with the real thing, because it is so expensive. If you try to actually use lacquer thinner in the paint, it will clot up a bit, but it does work in small repairs if you don't have the real thing.
Dried paint - once it "dries" - really, chemically cures - the only reliable means I have found to remove it are mechanical, not chemical. The thinner will not touch cured paint, you can safely clean the airplane with acetone or lacquer thinner. Fuel on bare colors can discolor it, for some colors, but it won't soak in or make it soft or sticky. It's tougher than the 2-part urethane you put over it.
It takes a good 12 hours at normal room temperature to become completely immune to fingerprints, much slower or never below 50 degrees, and much faster above 90. It will continue to cure for about a week, at which point, it's like it was baked on, glass-hard, or like the paint on a refrigerator. It will sand OK with wet/dry paper no matter how long it has been, and it won't gum up the paper used dry, but it's vastly tougher than almost any other hobby paint.
It dries very shiny, and if you could keep the dust out of it for 12 hours, you could at least imagine using it with no clear, even on a nationals-quality airplane. I paint in my bedroom, that isn't happening.
Brett