One these days im goint to just start a sticky on all these techniques.
Carlo...there are links...but they are scattered about in forums....so I will have to see if I come up with some that apply. Give me a bit...I am swamped with work and project deadlines at the moment.
The hairspray and the salt method are the approaches that seems to be the current standard/en vogue....however, there is never just one method, most often, to get the proper look and variety and prototypical effects, you will likely need to employ a variety of techniques....especially at the larger scales. Some of the chipping techniques that one would use for chipping:
Sponge paint applied chips
Brush painted chips
Rubber cement or masking fluid chipping (I personally don't care for this approach...and know of only a small number of people that do this well and realisticaly)
Per Olav does a neat technique with bare metal foil.
Also you do not want to forget "Positive Chipping"......this is painting in chips of color, in corners and crevaces and surfaces where paint chips and flakes might remain....but there is none on the model, from/due to, the chipping technique used.
Will write more later......