What chemical should I use to thin UV cure epoxy? The epoxy that I am working with is UV curable with a cycloaliphatic epoxy resin base. I am trying to reduce the viscosity. Whatever I add to thin the epoxy, it needs to be able to evaporate off so that when I cure it, it's just the epoxy remaining. I have used solvents like acetone to thin 2 part thermal cure epoxies, but I am not sure if this is appropriate for a UV cure epoxy or which solvent would be best to use.
Adding solvents that need to evaporate, to your epoxy, can cause pinholing. You need a integratable solvent. Styrene monomer works well. You can get it from a fibreglass supply or by pyrolizing poly-styrene.

The monomer will combine with the epoxy so it won't need to evaporate out of the epoxy.