Plus, I would add that thinning epoxy is never done if you wish to retain strength. It's OK for i.e. brushed on epoxy fuel proofing, but never thin it to wet glass cloth. There are different formulations for different purposes, and you need to be sure to buy something suitable for wetting out glass cloth when laminating. The main point is that you want to maintain 100% solids in your resin, never any volatiles.

Hope this helps & Best Regards,

Spidey