Now you'd think, being female, that I'd know about this sort of thing, right? After all, I spend my time playing with hairspray and stuff... not. Apparently, as every graffiti artist worth their tag knows, it's not the spray paint that makes the difference, it's the nozzle. So what I need to do to get a finer spray is pull the nozzle off the top of the can and experiment with some different ones. So now I might have to go to the chemist and buy lots of cans with nozzles on them. Drat. Oh, and the other thing I should do, once I've identified the perfect nozzle, is to spray up in the air and let the mist of tiny particles fall down onto my perfectly prepared plate.
OR... I could go back to using resin as an aquatint and apply it by hand, using muslin stretched over a flour shaker to distribute the dust over the plate and then blow-torching the underside of the plate. Half my problem is that a lot of my equipment is still in boxes as I don't have a permanent studio space in which to work, but I think I do have a blow torch top lurking somewhere that I simply have to attach to a bottle of gas, so this may be workable.
The other part of the problem is that I often just don't have a range of techniques at my disposal - just whatever I learned in printmaking classes. So it's great talking to people with more experience than me, even though I'm left feeling frustrated at my own ignorance sometimes!