Topic: Red Kote and rust removal?

[Scott S]

 I picked up a CB500 and the P.O. had the tank lined with Red Kote. It's been sitting empty for 20+ years and, oddly, there's a thin film of powdery rust. The tank is solid and the paint is excellent.
 I've saved many a tank using every method imaginable. What can I do to clean this tank out and not ruin the Red Kote and/or the paint? I have some EvapoRust on hand.

[grcamna2]

Scott,I had many tanks done with RedKote and they lasted and would never have any rust through the years.
The way those pictures look,it could be that,if the tank Was actually coated with Red Kote? it had been thinned-out way too much and then on top of that applied way too sparingly.
I might recommend that you use a strong solvent such as(gulp  )Methyl Ethyl Ketone or something as strong to get every last bit of that stuff out of there;flush it all out with Denatured Alcohol as many times as necessary,then re-apply the Red Kote in the proper amount so it fully covers all surfaces.
The man who worked in the radiator shop(Al)who did many of these motorcycle tanks for me told me not to worry about removing the rust.The key is to fully prep inner surface to get it oil-free and then set-up a high volume/low pressure air blower to blow out every last bit of any moisture to get it dry as a bone in the Arizona desert  .
I have an Electrolux vacuum cleaner and use the outlet port with hose connected and keep that thing running for up to 12 hrs,etc. Ideally,take your tank out on a 90+ degree day in the heat of the afternoon and set it down on the boiling hot black asphalt for the duration of time it takes. The purpose is to remove ALL the moisure 100% inside because the moisture will keep the Red Kote from adhering to the surfaces.

[Scott S]

 If the Red Kote comes out and it's clean, I'll leave it bare. I've seen way too many tanks lined that didn't really need to be lined.

[Scott S]

 What will MEK do to paint? And rubber, such as the gas cap seal and petcock internals?

[grcamna2]

What will MEK do to paint? And rubber, such as the gas cap seal and petcock internals?

I recommend wrapping the complete outside of the tank with a type of protective paper and wrap each layer of the paper with duct tape especially around the filler neck;use clear plastic(carefully applied around the rubber gasket so that it seals)between the cap and filler neck as the MEK can affect the integrity of the rubber if kept in contact with it for an extended time.The old petcock(or a spare you have,just use it like a plug:install it,then remove it)can be used to drain the stuff out when it's finished it's work of the old Red Kote.I would refrain from draining it from the top because it can soak through the paper quickly.

[ekpent]

 I would start out first using something friendlier on paint like the Works toilet bowl cleaner to zap the rust. If not left in there too long probably won't hurt the red-kote but  may lift some if there is a big patch of rust under it breaking the bond. Start out safe and easy and work your way up the the dangerous stuff if needed. If you use the toilet bowl cleaner just have water and a hose at hand and keep the outside wet and flushed off incase you have a leak from a rubber expandable plumbers plug or the gas cap if you go that route. A good coat of unbuffed Turtle wax on the paint before you start is a good idea also.

[grcamna2]

If the Red Kote comes out and it's clean, I'll leave it bare. I've seen way too many tanks lined that didn't really need to be lined.

I like using a small container of BB's(inside rusty,bare tanks)and just keep shaking it(quite an upper body work-out)along with half a gallon of wash-gas in that tank then flushing it,when it's just a bare steel tank with rust inside;the BB's make the tank smooth inside and turn the rust to fine powder which can then be washed out.I like using a white 5 gal plastic bucket and keep rinsing the tanks until the wash-gas comes out clear:then you know it's clean.The Red Kote needs to be washed out of there,imo;the BB's can remove a bit of it but the Red Kote will keep flaking off over time if it isn't all washed off initially.

[Stev-o]

I would start out first using something friendlier on paint...

+1.  It really doesnt look like the coating was thick enough, or was removed?  I'd use Evaporust.

[Little_Phil]

I've seen way too many tanks lined that didn't really need to be lined.

Same problem, same tank, same colour, kreem?

[newday777]

I picked up a CB500 and the P.O. had the tank lined with Red Kote. It's been sitting empty for 20+ years and, oddly, there's a thin film of powdery rust. The tank is solid and the paint is excellent.
 I've saved many a tank using every method imaginable. What can I do to clean this tank out and not ruin the Red Kote and/or the paint? I have some EvapoRust on hand.

You'll need 5 gallons of Evaporust on hand to fill the tank so the whole tank gets treated at one time.
I don't know yet how the liner will be effected by Evaporust.  I have a 750 tank I got in a lot that I need to try it on that has been lined with a clear liner.
I just did my K5 tank that was unlined and it came out pristine. I rinsed it with kerosene as mentioned in another thread, then put in some 2 stroke gas to coat the tank with the oil.(1/2 gallon and turned the tank around and over to fully coat it)

Before and after pictures

[ekpent]

I've seen way too many tanks lined that didn't really need to be lined.

Same problem, same tank, same colour, kreem?

Looks like Kreme which is the liner I have seen fail the most. Stuff stays kind of like a rubber and gets flaky.On a GT550 I have the tank was so rusty under the Kreme that I was able to work the whole thing out through the filler hole in one large piece. I was amazed as I kept pulling and working that rusty stuff out.

[ekpent]

The toilet bowl cleaner method with some steel nuts and bolts or other agitator just takes an hour or so to try and plugging the holes with the right plugs is important but beware some pressure will build inside if you have good ones. Have never had a problem with paint on a lot of tanks but as I mentioned earlier thats why I do it outdoors with a hose and sprayer to keep it wet and rinsed off on the outside to clean and dilute any possible leak. Really important to get it dried out quickly (shop vac on blow with nozzle stuck in tank) and get some gas back in it quick to keep flash rust at bay.

[Scott S]

 Letting it soak with EvapoRust. I'll have to rotate it over the next several days. We'll see how it turns out.

[newday777]

Letting it soak with EvapoRust. I'll have to rotate it over the next several days. We'll see how it turns out.

How much Evaporust?

[Scott S]

 About two gallons.

[Kenzo1979]

I removed Kreem from 3 Tanks.  MEK, and a length of chain for agitation.  Used a 1 1/2”???(hmmm can’t recall the exact size now) pipe test cap - plumbing section, expanding stopper with a wingnut - along with tinfoil to seal it.  Also use a tinfoil wrapped cork or rubber bung in the petcock hole.  Take the gas cap off completely.  I wrap the tank first in tinfoil then in paper with painters tape, then plastic on top. Just pour it out carefully and you won’t hurt the paint.  CAUTION:  Pressure will build a little inside, so remove the test cap slowly like you were opening a shaken beer.  Strain and repeat, usually back to bare metal after second treatment.  Then flush with water, blow out with compressed air and rinse with xylene.  Then I recoat with clear Caswell.   If you’re recoating, have it ready to go before it flash rusts.

[grcamna2]

I removed Kreem from 3 Tanks.  MEK, and a length of chain for agitation.  Used a 1 1/2”???(hmmm can’t recall the exact size now) pipe test cap - plumbing section, expanding stopper with a wingnut - along with tinfoil to seal it.  Also use a tinfoil wrapped cork or rubber bung in the petcock hole.  Take the gas cap off completely.  I wrap the tank first in tinfoil then in paper with painters tape, then plastic on top. Just pour it out carefully and you won’t hurt the paint.  CAUTION:  Pressure will build a little inside, so remove the test cap slowly like you were opening a shaken beer.  Strain and repeat, usually back to bare metal after second treatment.  Then flush with water, blow out with compressed air and rinse with xylene.  Then I recoat with clear Caswell.   If you’re recoating, have it ready to go before it flash rusts.

Sounds very good 

[TwoTired]

All the acids will dissolve/convert both rust and metal.  Electrolysis removes rust without harming the base metal.

[Scott S]

 Well, it's been sitting with about two gallons of EvapoRust in it for about ten days now. I would tilt it, rotate it, lean it, etc., so that all sides got coverage.

 Hope to empty it today but I found that the Red Kote has failed and is coming off like a bad sunburn. The tank is spotless where it came off and the EvapoRust touched it.
 I poured out about half the E.R. and put a couple of chains and some stones in it. Shook well and got a little more out, but there are areas where it (the R.K.) is still on there pretty good.

 I'm unsure what to do at this point. Keep soaking it with E.R. and shake it with the chains inside? Try a Caswell or POR-15 kit that is aggressive and would remove the R.K., but I am scared to death of damaging the paint.

 

[Scott S]

 Do you think vinegar would do anything at all to the Red Kote?

[ekpent]

I don't think the vinegar would peel anymore Red-kote out and after seeing what that stuff did to some bolts I was soaking and forgot about I would not leave it in for a super long time. Probably getting to the point where you might have to move to phase 2 and some aggressive solvents if you want it all completely out.

[grcamna2]

I don't think the vinegar would peel anymore Red-kote out and after seeing what that stuff did to some bolts I was soaking and forgot about I would not leave it in for a super long time. Probably getting to the point where you might have to move to phase 2 and some aggressive solvents if you want it all completely out.

+1 Scott,wrap the tank up good.

[Scott S]

After a closer look, it appears the 90% of the Red Kote is gone. There are a few small, loose spots. The largest is right below the filler neck, on the backbone; about a 4-5" long X 2" wide area that is still pretty hard. Visible in the latest pics.

I found that acetone will remove it but I really, REALLY don't want to damage the paint.

What if I:
- wax the tank again and don't buff it off
- wrap tank with Saran wrap, followed by painters tape
- possibly repeat step two
- cut a thick garbage bag to make a cover and wrap/tape again
- put a chain and BB's inside, along with a cup or so of acetone
-shake like crazy
- dump

What are the odds that I can do it without damaging the paint?

Another option is a Caswell kit. Caswell doesn't use any kind of etched or acid and can even be applied over rust (which I don't really have).
What about getting rid of the last couple of small, loose spots of Red Kote and just apply Caswell OVER that stubborn patch on the backbone?

[ekpent]

Like Cal mentioned if what's left is adhering well just run it as is. Petcock has a filter and if it becomes an issue of some kind you can always go back in.

[Scott S]

Acetone if used carefully won’t abuse your paint. If happen to spill any on the paint, rinse it off well with water promptly.

A better option is to simply leave it as it is. The Red Kote is fully adhered and who gives a bump over a few spots of liner in your tank? It’s an emotional issue, and there’s deeper things to care about. 

 
 If it had been just the big "scab", I would have left it. But it was still wanting to peel in a couple of spots.

 We put a thick coat of wax on the tank, wrapped it in two layers of plastic bags, dropped in my chains and a few ounces of acetone. Before putting the cap on, I used a Scotch Brite pad on the end of a screw driver to scrub the back bone. Gave it a good shake and rinsed well with water.

 Got out all of the remaining Red Kote, leaving only a stain where the scab was. Even though I blew it out with air, used denature alcohol, my heat gun, and sat it in the bed of the pick up in the blazing sun, it did want to flash rust. The acetone must have "undone" whatever finish the EvapoRust left. Gave it a quick rinse and put about two ounces of Marvel Mystery Oil in it.
 It's all ready for storage now, until I get the bike back together.