Rusty Steel Tank

I have an original Roadster (1974) tank with rust inside I need to treat and seal.

There is plenty on the forum regarding Evaporust and POR15 etc.

What are the current thoughts on rust treatment based on experiences.

Thanks

I've used Evaporust on my Ducati 900SS tank and it worked really well. I never sealed the tank afterwards and it still looks great inside even after a year. It's a slow process however because I only had a gallon of the stuff so I had to rotate the tank every day to get coverage on the sides and top. Roadster tank is pretty small so it may require less gymnastics to get full coverage inside the tank. The stuff is non toxic and safe on painted surfaces which is a big plus. You can re-use this stuff for all your little parts too. Just let the debris settle or run it through a paper filter.

I haven't used POR-15 personally but I my current Roadster tank was sealed with POR-15 when it was expertly repaired by Ross Thompson and it's holding up just fine. I've used Caswell with great success but once you coat the tank, you're committed to it. Unless your tank leaks I might try skipping this step. I will say that any tank sealer is only as good as the tank preparation done before. If your tank only has surface "flash" rust I would try skipping the sealer process and maybe just rinse the tank with some phosphoric acid which leaves a phosphate finish on any bare steel. My last jug of Evaporust included a spray bottle of Rust Block which I think is simply H3PO4. Just keep the H2O out of the tank afterwards.

Everybody and their dog has some ideas of rust removal and treatment. My two cents:

I used non-food grade molasses on a rusty 650ss tank. Worked very well, although it took about a week. When I rinsed it with water, very minor surface rust appeared. I probably should have hit it with phosphoric acid after the first rinse. I believe molasses have the same active ingredient as Evaporust at a tenth of the cost.

As for coating after rust removal, pick your religion. Prior to coating, the surface needs to be super clean, which in the real world can prove difficult. And when the coating fails, it is extraordinarily difficult to remove, certainly without ruining the tank paint. I look at this way. If it took 30 years to rust, and you get the steel surface clean, leave well enough alone. However, if the tank is compromised (pitted, etc) coat it and pray to your gods that it won't lift off.

Stephen Hill

Pretty much any of the rust converter solutions will work. I used the metal treatment and sealer available from Bill Hirsch. It's been 10 years and is still perfect.

http://www.hirschauto.com/Gas-Tank-Sealer-_-Repair/products/4/

Ended up with the POR 15 Motorcycle Tank Kit, a 3 stage process with cleaner, etch and paint.

Very time consuming, particularly the cleaning / prep, but appears to deliver a nice result, a bit like a silver ceramic coating. Don't get any on your paint job, be warned.

A good product for steel tanks it appears. I will report back annually.