I've never really measured out exactly how many parts alcohol. I just mix the epoxy and add alcohol until it reaches a consistency that will brush on easily. It usually doesn't need much alcohol. I'm guessing mabye .75 parts alcohol. Add it in little by little until it will brush on.

The epoxy/alcohol method works. Last season the fuel tank in my Piper Cub ruptured, creating a swimming pool of 30% in the bottom of the fuselage. I blotted it all out with towels and wiped the inside dry. The fuel never leaked even through the thin sheeting. There was NO damage at all.