Don't bother to thin it, just put on as thin a coat as you can then gently heat it with your heat gun. It gets very thin and is absorbed into the wood much better. The heat will also speed up the cure. Just don't overdo the heat, don't get it so hot that it bubbles. If you need the strength of epoxy, I recommend that you do not thin it with anything other than the manufactures recommended thinners or you may suffer unwanted complications.