Been a while... Tank Rust!

Just to throw in my 2 cents:

I already de rusted two tanks.one was awful (kz400).
I tried the electrolysis method...workes but not perfectly.
I did not use any mechanically abrasive methods and this is how i got it derusted perfectly.
I used phospor acid of the firm 'wagner'.
First de greased with acetone.filled the tank with 250ml of acid and warm water after one day it was spotless.
Then i rinsed it out with water.
Used alcohol...dried and used some resin of the same firm...worked a treat!

Tune-A-Fish said:

Oh, so you don't dump it in and leave it soak you pour it out and just keep rinsing

Click to expand...

If it's spot rust, then pour it in and swish it around so it coats the inside of the tank, then dump out excess into a bowl. Wait 30 minutes to an hour. Inspect. If all the rust is either gone or turned black, then the acid did its job. If you can still see browness, then repeat. Filling the tank and letting it soak is the best way, but that requires the amount of acid to be enough to fill the tank. A small dirt bike tank- no biggie. A big touring tank would get expensive. You can also shake it around every so often and just leave the liquid in there. Regardless, the acid can be used over and over again. It loses it's etching ability a little with each use. When etching printing plates, we use the same acid bath sometime hundreds of times, but we have to extend the bite time a little more for each subsequent bath. I haven't tried (I'm curious), but adding something like cellulose (or starch) should make it stick better. Just a little, not as much as Naval Jelly. If you look at the MSDS for Naval Jelly, it lists polysaccharides. It's the polysaccharides that make Naval Jelly gel-like. Without it, it is basically the same as the etch (etch doesn't have sulfuric acid, Naval Jelly does). We use cellulose (a polysaccharide) in Ceramics to encourage glaze materials to stay in suspension and to get the glaze to act more like a paint, as well as to help it adhere to the surface of the form.

Ryan Stecken said:

Just to throw in my 2 cents:

I already de rusted two tanks.one was awful (kz400).
I tried the electrolysis method...workes but not perfectly.
I did not use any mechanically abrasive methods and this is how i got it derusted perfectly.
I used phospor acid of the firm 'wagner'.
First de greased with acetone.filled the tank with 250ml of acid and warm water after one day it was spotless.
Then i rinsed it out with water.
Used alcohol...dried and used some resin of the same firm...worked a treat!

Click to expand...

FYI, if you want to degrease and etch in one sitting, just add a $2 bottle of Isopropyl alchohol to your phosphoric acid. That's essentially what Metal Prep is that paint shops use. It degreases and etches at the same time. I'm sure there is a limit to how greasy, but still should work for most applications we would need it for.

Thank you for the advice.hope i can get that stuff in austria.our governement is really eager to ban most of the stuff that is useful.

I recently did nearly 5 gallons of white vinegar, on a 2 day soak(maybe a bit less). Also made a little stand because I know I'll do this again and shaking/holding/draining a full 5 gallon tank can be a bit strenuous. Had some scrap wood knocked er out.


Dumped it.



Flush with 2-3 gal of distilled water. Warm/mildly hot(brought to boil and took off the stove for 30 minutes in the garage as I finished up the petcock(WARNING: Avoid K&L petcock eBay/Moto seller kits. All latger than OEM and sealed incorrectly. I eventually replaced with original OEM (aside from the large o-ring for the mount to tank).


My lovely assistant Layla helped me out with the distilled water.


Drain the water and dump 4-5 bottles of isopropyl rubbing alcohol (91%, prevents flash rusting), shake and dump. That rids of most of any remaining water. Be careful with excess/dumping alcohol on tank during drain. It can damage the clear coat a bit. Best to tape or immediately have a rag worth a little abut of gasoline to clean off immediately. Once the alcohol is out, brim it with gasoline and that's it. First few fill ups seal it up enough and just remember to always store it with a full tank whenever it's left sitting for for more than two weeks. Not all that hard! Costed me less than $25....

Sounds like that went well and hell the drain rack can second as a shoe shine stool

It was hotter than the gates of hell in the shop last night so an early am run tomorrow will be the plan to do my tanks, I did get alcohol rinsing and to add to the acid solution per Eric's advice

Well the results are in:

KZ tank



I used the Metal Rescue for one hour and it took out the big rust, but not in the weld seam. I used the phosphoric acid on the second try and also on the CB tank which was about the same with less blistering rust, I am wrapping fascia also so not a lot of pictures: I wont even try the last solution, the phosphuric worked sweet and coating with pre-mix will keep it clean

first is the KZ second CB, cleaned up my old fire hose attachment nicely!!

Tune-A-Fish said:

Well the results are in:

KZ tank

I used the Metal Rescue for one hour and it took out the big rust, but not in the weld seam. I used the phosphoric acid on the second try and also on the CB tank which was about the same with less blistering rust, I am wrapping fascia also so not a lot of pictures: I wont even try the last solution, the phosphuric worked sweet and coating with pre-mix will keep it clean

first is the KZ second CB, cleaned up my old fire hose attachment nicely!!

Click to expand...

How many gallons of metal rescue and how long did you soak? Rotate so all parts of tank were touched or did you shell out the dough for 4(+?) gallons of metal rescue?

Any metal/tools exposed will be cleaned of rust but will flash rust soon after and potentially get worse Chuck78 said he found a screwdriver or possibly a wrench under his workbench like a week later totally rusted back up!

Nice. Ain't science fun?


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I only used 1/2 of one gallon of each and just gave the metal rescue a shake every time I walked by for about and hour and thirty minutes and changed the acid 3 times in both, then rinsed with water letting it over flow for 10 minutes each followed by a full bottle of alcohol in each... then... I have been giving both a shake with 50/50 2-stroke oil and gas.

I have used the pool acid (muriatic acid I think) before and it works, but too good and it flash rusts right away, I typically just use the slosher method with PB and gas, but I want to make a mechanical slosher so I need a solution that wont explode Now with this method unless the tank is really bad, I don't know if its needed. Wish I had time to do more pics and stuff, but it's so dang hot and so much to do ???

Thanks for all the input guys, and I guess Erick's solution is the WINNER! ;D