I know this may be the wrong location for this, but I basically painted the inside of a gas tank, so I'll post here:
I am in the throes of restoring the gas tank from my '74 Honda motorcycle, and it had some minor interior rust, so I decided to try out the POR-15 tank kit for bikes. It came with a quart each of Marine Clean and Metal Ready, and a half pint of sealer. The tank is built of pretty thick metal, holds about 4 gallons or so, and has a somewhat convoluted bottom. I stripped the outside and removed all the hardware including the petcock and filler cap.
Last night I sealed the petcock hole and mixed up a batch of Marine Clean with hot water, and filled the tank with it and left it in the sun for a few hours. I drained it an rinsed it and got a concotion that looked like iced tea with clots in it.
Then I filled the tank with the metal ready (Phosphoric acid) and sloshed it around for a half hour. Man, that really cleaned the thing out, there was not a spot of rust in there afterward. It looked really good and I could have probably left it that way, but I think it would have rusted again since there was no oil protecting it from the air.
Finally, I poured in the sealer and sat on the porch and sloshed the tank over and around for 30 minutes, and drained the excess (to prevent puddles).
It looks like I painted the inside of the tank silver. It is pretty strange looking stuff. Now I have to wait a few days to put fuel in it, but it looks great in there. I still have to prime and paint the outside. I already filled a couple of dents and it should be ready to go in a week.
It looks like it will work really well, and I hope the liner lasts a long time because it would be a major pain to strip it out of there.
