De rusting a tank, pics included

I posted this on the sohc4 forum after someone stared a vinegar de-rust thread, I thought someone here might get a kick at the pics I took of it as well. I filled the tank with plain white vinegar and let it soak for a week straight. Lets see if posting pics works.

This is what the 78 Kz1000 tank looked like when I brought the bike home, pretty rusty through out the whole thing


One day into the vinegar soak I could wipe off the light rust around the filler hole and neck inside.


This is 6 days of soaking, I dranied the vinegar into a bucket. Some loose flake was still inside that didnt pour out when I drained the tank but man its looking clean.


I strained the vinegar back into jugs through a t-shirt I use as a rag, this is what was at the bottom of the bucket.



I was really surprized at how well it worked, but seeing as I didn't have baking soda or acetone or methyl hydrate on hand for a good rinse I just re filled the tank with the strained vinegar as a bit of flash rust had started to form. I dont think there will be any rust inside after I drain and properly rinse the tank.

Just to be clear, I filled the tank and left it for 6 days. No shaking with drywall screws or chain, I took the petcock off and wrapped a couple layers of electrical tape over the hole and a second layer or two of tuck tape I had around the house. No leaks from the tape and the paint was fine anywhere the vinegar spilled on it.

After the second week of soaking I drained and quickly rinsed with baking soda and water, rinsed with warm water till no rust flakes were coming out. Then a rinse with acetone and methyl hydrate and blew the tank dry with a compressor. I managed to avoid any real flash rust, gave it a coating of 2stroke oil. It's totally rust free, I got another good pile of rust out of it on the second soak.

Nice post...thanks!

In my experiences (I tried the Por 15, muriatic, vinegar and oxalic acid) getting the rust out was the easiest part. Keeping the crap off your paint and rinsing before the flash rust formed was always the hardest part. That stuff can really form fast!

@apbling, the flash rust starts pretty quick. I had a tiny bit start on the top of the tunnel below the filler neck, I think the key is to neutralize the vinegar right away and dry it out as fast as you can. We'll see how it looks by the time I get the Kz running, it sitting in my laundry room which is heated.

As for paint damage, if you do a straight vinegar soak with out any other acid type added your paint isn't affected, I spilled vinegar on the tank and nothing was harmed. That was one of the main reasons I tried the vinegar method, not as corrosive on me or the tank or the environment.

Molases and water mixed at 1 part molases to 7 parts water will do the same job make up a brew fill the tank up for about a week you will get the same result.Molases is cheap to buy so if you have a big enougth tub to put a rusty frame in it will clean the rust out of all nooks and cranny,s comes out a bit messy you can clean it all of easily with a water blaster but it will need painting straight away or it will start rusting allmost straight away

I picked up a VERY nice shape (externally!) spare tank for my '83 KZ1100 LTD - for a future custom paint job. It had a full coat of surface rust on the inside - all over the inside. I used a cup of Oxalic Acid in a gallon of warm water, soaked the inside of the tank for about an hour. with LOTS of strong agitation every 10 minutes or so to fully distribute the acid. The acid ONLY affects rust, and doesn't harm paint in the least. No pictures of the "before", but we all know what rust looks like - here's pics of the inside AFTER treatment:

Not bad at all, in fact, good as new!

Thanks for posting the info. Your tank looks really clean

Great ideas here...I'm going to be undertaking this next week...

Hey Gary, where did you get that Oxalic Acid?

I can't seem to find it.

Nice solutions, lucky for me we don't seem to have rusty tank problems in this area, I've yet to own a bike that had rust in the tank.