Removing Rust from a Tank

[Johnny3D]

I acquired a tank which has no dents in it but it does have some rust inside (not a horrible amount, but some). I'm looking to remove the rust from inside the tank. I am also removing the paint from the tank and will be using bondo to smooth out where the badges were attached, so saving the paint isn't an issue. I've been reading a lot of articles/posts about doing that and watching a lot of videos on the various methods of doing that, however, I'm not sure which would be the best method(s) for me to use to restore the tank.

What I'm wondering is what is the best method you have used? How good were the results from the method you used? What were some things/catches you figured out along the way?

My primary goal is complete rust removal from the tank. My secondary goal is to do it without costing a lot of money.

Here are the main methods I've heard about:

1. Electrolytic rust removal (using washing soda, water, an iron sacrificial rod, and a manual battery charger to remove the rust inside the tank).

2. Bunch of washers or sheet rock screws and shaking the heck out of it for a long time over and over.

3. Molasses and water soak.

4. Vinegar soak

5. Various acid based approaches

I've been leaning towards trying the washers/screws method followed by the electrolytic method, but I'm really not sure. So if you have a tried and true method that you've used to achieve rust removal from a tank, I would love to hear about it.

I'm not in a huge hurry or anything like that. I have a lot of work to do on my XS400 before it'll be road worthy. Also, when I do decide on a method and give it a go, I'll be sure to take plenty of pictures and write up a how to (or a how not-to if I totally mess it up).

 

[Wolfe_11B]

Metal rescue. All rust gone in several hours, and no harmful chemicals or batteries used.

And you can reuse the stuff many many times.

I know electrolysis is used a lot, but just know that it only works 'line of site' to the anode/cathode. It's time consuming as well.

Try vinegar and salt first. Cheapest, and will probably do the job.

 

[BBS360]

Seconding metal rescue. Trying electrolytic removal was cool but messy and inconsistent.
Metal Rescue was easy.

 

[Johnny3D]

Cool! Thanks for the info, guys. I found a place not too far from my town where I can buy some (I live in a small town up in the northern part of the Black Hills). I think I'll be giving that a go!

 

[BBS360]

One jug won't fill the tank but if you slosh it around it will remove all the rust. I threw in a bunch of clean metal bits, sealed it up, and rotated it in different directions while watching some TV.
The trick is preventing flash rusting afterwards. Mine did the first time as I didn't do anything to the inside. Even atmospheric moisture will rust the surface quickly. A quick second treatment got rid of it.
Some people pour some oil in to coat the inside. Filling it with gas right away, all the way, will work too.
I left a film of metal rescue in there then had the tank lined the very next day.