Cleaned the insides of the skins with MEK and then scored the areas to be sealed with scotchbrite pads.
There are some stains on the inside of the skin where I dropped sweat onto the tank. It being Houston in the summer, average temps in the garage are 90ish (32 C) so this is a constant problem.
I thought about acid etching everything but in the end decided not to. A couple of passes with MEK and scotch brite seemed to do the job.
