Evapo-Rust - Rust Removal FTW

I've used this product for years and am currently restoring two gas tanks.

The first pic shows how much rust was inside the tank. I poured 3 gallons of Evapo-Rust into the tank and moved
the tank to different positions for a couple of days. It removed all of the rust. There are some black stains inside
the tank but it's cosmetic at this point. I'm waiting for a Caswell epoxy gas tank kit to come in.

I've derusted a lot of GPZ1100 parts with just three gallons. The liquid is totally black but it is still active.
The pic of the top of the tank shows the center shiny and free of rust. I dipped a maroon Scotchbrite pad in
the heavily used Evaporust and removed the rust from the top-center of the gas tank in less than 3 minutes.

This product is amazing and it's biodegradable.

Looking forward to giving it a try. I've been tripping over a five gallon bucket of the stuff for about a month.

I'm sure you will like the Caswell epoxy tank liner as well. A few years back, I used it on an XT225 tank that kept springing pin hole leaks. It lines the tank with a thick, hard coating of epoxy. I could probably peel the metal off and have a usable epoxy tank.

If it doesn’t leak why coat it.... it only presents a potential problem in the future... I’ve cleaned tanks before and by just keeping fuel in them will keep the rust from returning.... the included photo is tank coating settling to the bottom of the tank after sitting unused for a few years... I used acetone to remove it (seriously a PITA) and have used the tank for several years uncoated and no rust has returned...

Caswell is a great product. Be careful in summer time. Choose a warm sunny day and leave the 2 cans sitting in sun. Softens it up so it can be worked with. It says it has an average of 20 minutes work time. But with warmer temps. the 2 parts may react quicker. Just like adding too much hardener to body filler.
And a few drips of lacquer thinner can reduce it if need be. I saved a set of 1968 OEM harley fat bobs with the stuff. I will use it again when need be!

Mikaw wrote: If it doesn’t leak why coat it.... it only presents a potential problem in the future... I’ve cleaned tanks before and by just keeping fuel in them will keep the rust from returning.... the included photo is tank coating settling to the bottom of the tank after sitting unused for a few years... I used acetone to remove it (seriously a PITA) and have used the tank for several years uncoated and no rust has returned...

I've removed failed tank liners before (Kreem). Most tank liners are outdated. However, this Caswell epoxy won't deteriorate.

Having a gas tank leak after painting it is a huge headache. I like the fact that the epoxy will add thickness to the sheet metal.

Maybe I've just been very lucky, but my 1977 KZ650-C1 fuel tank has never been coated with anything and has no rust at all. I'm the original owner of the bike. I usually (but not always) keep the tank at least halfway full, so maybe that has helped? Since gasoline does not promote rust it seems to me putting coatings inside the tank is unnecessary if the inside if the tank is clean and rust free. I've read too many cases where the coatings have failed and the owners have a tough time removing their remnants. Ed

I've restored a bunch of tanks and can confirm Evapo-Rust is great stuff. Only thing I don't like is the price. Realize that it has a limited life span; after a lot of usage it loses it's effectiveness.

While I like the ER stuff my preferred material is phosphoric acid to clean tanks. You can buy a gallon of the stuff from Home Depot for less than $20 and it can be used again and again. Just pour it back into the bottle when done with it.

As for sealing, I've had good success with both Por-15 and Caswell's. Caswell's is crazy thick so read the directions and thin it to the max allowable amount, which isn't much, but every little bit helps. If the metal is deeply pitted than sealing is recommended but if the metal is sound after derusting I'd leave it. One nice thing about using phosphoric acid is that the metal builds up a bit of a coating which helps delay flash rusting after rinsing. I use water to rinse followed by alcohol to get the water out fast. If you are going to leave the tank and not coat then hit it with something like WD-40 or some sort of oil to coat it. Don't do this if you are going to coat though or the sealer won't stick.

Mikaw wrote: If it doesn’t leak why coat it.... it only presents a potential problem in the future... I’ve cleaned tanks before and by just keeping fuel in them will keep the rust from returning.... the included photo is tank coating settling to the bottom of the tank after sitting unused for a few years... I used acetone to remove it (seriously a PITA) and have used the tank for several years uncoated and no rust has returned...

What brand coating were you using?

Skidmark, I have no idea the PO coated the tank... I was the shlub that had to get it out...

I agree. Do not coat a tank that only had surface rust that cleaned up well. I have cleaned many tanks and only coated one. The XT225 tank was rusting through and developing pin hole leaks. Caswell fixed that by creating an epoxy tank inside the steel tank. I did not use Caswell to prevent future rust, but to prevent me from having to buy new tank.
Attached is a patch of Caswell I drained from the tank after rolling it around for the recommended 20 minutes. I picked it off my dirt parking area after it cured

20 to 30 years ago tank sealer was pretty rare (compared to now). It was something done as a desperate last-ditch effort to stop a rusted tank from leaking... and often failed. But somehow people (millenials and younger) seem to think it's a prudent, preventative measure. So now every other bike I look at has a tank full of melting white or red goo inside gumming up petcocks and carbs. Then they try to sell the bike saying it just needs a quick spray of carb cleaner. Yeah right. I haven't come across one tank that was lined and was not affecting the petcocks and carbs.