Caswell Tank Sealer Meets Benelli / Aermacchi Tank

Yesterday I got around to applying the Caswell Epoxy Tank Sealer to the tank innards.

Like I mentioned before, the tank was solid, but very rusty. Caswell is supposed to bond to rust, but they advise to throw in some sheetrock screws and acetone to break up the loose bits, which I did, but didn't feel like I got enough of the flaky rust off. I then decided on doing the vinegar trick, but instead of a day I just used it for half a day and then applied a pressurized stream of water for the rinsing and acid neutralizing (just used baking soda). That worked out much better at getting some of the stubborn stuff out and did a decent job of cleaning the rust - if I left the vinegar in for a whole day or two it probably would have cleaned everything, but this epoxy doesn't really care about rust so neither did I. As far as drying off the tank, I connected the hose for my vacuum to it's exhaust port, essentially turning it into a powerful blow-dryer, worked like a charm. Onto applying the sealant.

Caswell tells you to wrap the tank with glad wrap, followed by a layer of aluminum foil, and then another layer of glad wrap. As you can see above, I skipped the aluminum foil part and instead went with 3 layers of plastic wrap, followed by some masking tape for extra protection around the top of the tank where I'd be pouring in the epoxy. I found that this much protection was unnecessary (especially if you drain the epoxy out of the petcock holes) for the most part, but I did get a few drops on the masking tape part when I flipped the tank over after draining the excess sealant, let me explain. This Benelli tank's petcock holes are internal thread, so in order to protect the threads from getting epoxied over, I threaded in some M10x1.0 bolts wrapped with teflon tape and had to drain the excess out of the top which was a little messier. I'm confident that if you are careful and have externally threaded petcocks (like on my BMW) you could drain out of the petcocks and not spill a drop on the tank... but anyway...

The stuff is the consistency of a thick molasses or honey and must be spread around the inside of the tank slowly - Accomplished by sealing off all holes and sitting for 15 minutes with a tank in your lap rotating it around. They advise to do the job at a temp of 70F and that just happened to be the temperature inside my house exactly yesterday (we don't have central air). Caswell says half the supply they give you is good enough for a tank of 5 gallons or less - I found that to not be the case. This tank is 3.75 gallons and I got about 70% or so coverage, so I had to mix up the remaining supply and add it (I waited 4-5 hours after the first batch as the stuff was still tacky, but more or less set in place, Caswell says a second coat can be added within the first 24 hours as long as the stuff is tacky). After all was said and done, there was only 4oz. of excess epoxy using the entire kit, so I'd advise using the entire kit right from the start if you're doing a similar job. If this was the stock Aermacchi peanut style tank I think the half would have been fine.

It's been close to 24 hours of curing and the stuff is rock hard. They recommend letting the epoxy cure for 24-36 hours before adding any gas to it, but it'll probably be 48 hours before I get a chance to gas it up. I couldn't get a good picture of the coating, but it looks like a layer of glass, probably a a couple millimeters or so thick. I love the thickness of it, but I don't like the fact that it's clear, because ignoring the gloss finish of the sealant, it still looks like a shitty tank on the inside (i.e rusty, even if encapsulating and no longer rusting). I wish they added a black dye to the epoxy or something, just to mask the appearance of the tank inside. Oh well, as long as the stuff works and it definitely seems like it will.

I'm still waiting for the Aermacchi tank side decals to arrive, but I couldn't resist adding the ones I bought for the stripe area.

It's looking good and now I really can't wait to get this thing back on the road. We're in the home stretch!