Ludo,
one of the most important things I have discovered whether using hairspray, or AK's chipping fluids is the paint you are using. Vallejo does not like to chip, it comes up in larger sheet like chips while Tamiya paint gives you those tiny little detailed chips. Badger Model Flex paint is somewhere in between and I'm still experimenting with lifecolor paint.
Thickness of the paint applied has a huge effect as well, a very thin mist will come up easily in tiny chips, a heavy thick coat will require much more work (and has a tendency at times to crack on the surface). Sometimes several layers of misted paint - 1st layer chipped and then varnished over and misted again and chipped and varnished... etc. results in the most desirable scaled effects.
Unless you have nailed it down, I would suggest to keep experimenting. It's not much fun having to strip the entire layer of paint you wanted to chip to get back down to the original paint to start over, frustrating isn't the word to describe what that was like.