RT4957 hi,
yes you're right, i suppose this question should be in the techniques forum, but i know what you mean: i think most people read either here or in the armour forums!
anyway, i think your "bubbling" is becuase you are using say acrylic on acrylic (right?), so that the thinner from the wash is eating into the original coat? use a protective layer of future, which is what i normally do..
talking of which, i usually follow the experts...
check out
swanny's site:
http://www.swannysmodels.com/Weathering.html
this link goes striaght to what you want, but there's loads of other stuff on it as well. enjoy....
regards,
nick