More spray paint antics

It's dashed tricky, that spray paint aquatint! I wonder if it's because I bought car enamel rather than a different kind of spray - I may have to investigate whethere something else gives a finer mist. My biggest problem is atmospheric: high humidity and/or a stiff breeze make spraying anything evenly with fine droplets a bit of a problem, and I have to do it outside because I can't use all these solvent-based products in the office I share with my husband...