Here's something else posted on another forum......this is re masking paint:
"......a great liquid masking product from Windsor Newton, "Colorless Art Masking Fluid". It's meant for use with watercolors and paper but works great for modeling as it masks nice and comes off very easily without damaging the undercoats of paint. Basically you paint it on with a brush then clean the brush in soapy water. It goes on whitish, but dries clear."
This stuff might have some interesting possibilities for weathering and such also.
Marc
Especially when flicked on using a stiff bristle brush. Great rusting!
How does it stand up against enamel and lacquer?
Bill