[CrateCruncher]

Acetone is one of the most volatile solvents available to the public and is a poor choice for airbrush use. It often evaporates out in midair leaving clumps on the painted surface. This can be good if your going for a rusted texture or fuzzy fabric but I get the feeling thats not what your after.

For thinning TS colors I only use lacquer thinner and thin the decanted paint down to a milk viscosity as a general rule.

For X and XF colors I use X-20A which is a $$ ripoff considering its just water and alcohol but I so seldom use acrylics the stuff lasts forever. Maybe someone else has the "secret formula" for X-20 acrylic thinner and will chime in.