More questions about fuel tank sealants

Okay, MORE questions about using the POR-15 Fuel Tank Sealer…..So, the autobody place where I bought it didn’t actually have any SMALL cans of fuel tank sealer, so I got this one:

I’m betting a quart can is just a BIT too big…. So, I thought to myself, I can just use SOME of it now, and SOME of it later (when I have to do the NEXT tank…. Except, then I went and did some research and found THESE instructions from POR, which say once you OPEN the can you CAN’T reclose it or it might EXPLODE (no, seriously… That’s what it says…). Hmmmmmmmmmm….

So, I’ve got enough of this stuff for like, a tank on a 67 Chrysler, I’m sure… And the instructions say use the entire can…. So, what do I do? Do I try doing TWO tanks (I just happen to have a couple that could use some sealant)? Do I risk opening the can, using PART of it then resealing it? I’m guessing I should be doing this in a “well ventilated area”, so what temperatures are too low for doing this in? Do I just take the stuff back and go with really cleaning my tank out?

Okay, I’m beginning to understand why it might cost $200 to line even a tiny tank… ’cause it blows through a whole can of the sealant even for a tiny one….