Before you thin Epoxy please read this

http://www.westsystem.com/ewmag/14/ThinningEpoxy.html

Thinning Epoxy with 5% Acetone or Lacquer Thinner can reduce the viscosity by 60% but reduce the strength by 35%.. Alcohol can reduce the strength by 50%
Any one of the 3 can cause shrinking or cracking if to much is added.

Recommended method to thin epoxy is to heat it to around 100 degrees. That will reduce the viscosity 30% and not effect the strength at all.
it may accelerate the cure time slightly.