Author Topic: Issues with flash rust during derusting (Read 5969 times)

algophobe · « **on:** August 18, 2016, 10:40:30 PM »

So i'm derusting the inside of a K2. i tried both electrolysis with sodium carbonate and vinegar with neutralization with baking soda as well. both methods work well, but the drying process produce what seems to be heavy flash rust, even if i use acetone or a blower. the moment it drys, the flash rust forms. i've looked all over for the answer but nothing has really answered my question... which is:

1. will this flash rust affect the bonding of Red Kote sealer?

2. should i treat it with a quick swish of CLR. but this will still need to be bone dry before the Red Kote is applied.

help!?!?!?! getting pretty frustrated.

calj737 · « **Reply #1 on:** August 19, 2016, 08:43:21 AM »

Remove ALL flash rust before using Red Kote. You could rinse and treat with Prep N Etch to insure proper preparation.

b52bombardier1 · « **Reply #2 on:** August 19, 2016, 10:17:42 AM »

I use a 1000 watt heat gun to get things dry very quickly. Then immediately coat it with POR15.

Rick

Sent from my SAMSUNG-SM-N900A using Tapatalk

Duanob · « **Reply #3 on:** August 19, 2016, 11:06:24 AM »

Why do you want to use a tank liner? Are there pin holes? If the tank is solid there is no need to line it. You are just creating headaches for the next owner.

Scott S · « **Reply #4 on:** August 19, 2016, 04:01:09 PM »

Or just swish around a couple of ounces of Marvel Mystery Oil or two stroke oil until you're ready to put gas in it.

beemerbum · « **Reply #5 on:** August 19, 2016, 05:09:00 PM »

Right after flushing the tank, spray the inside with fogging oil. Be careful not to blow the little red straw from the spray can into the tank. Don't ask me how I know this can happen.

algophobe · « **Reply #6 on:** August 19, 2016, 05:45:41 PM »

Quote from: Duanob on August 19, 2016, 11:06:24 AM

Why do you want to use a tank liner? Are there pin holes? If the tank is solid there is no need to line it. You are just creating headaches for the next owner.

just found out there's a pin hole. $:-\$ just wanted a thorough job i guess. supposedly they say that after electrophoresis, it should be pretty resistent to rusting?

algophobe · « **Reply #7 on:** August 19, 2016, 05:47:38 PM »

Quote from: beemerbum on August 19, 2016, 05:09:00 PM

Right after flushing the tank, spray the inside with fogging oil. Be careful not to blow the little red straw from the spray can into the tank. Don't ask me how I know this can happen.

hahaha. i had the same issue with swishing diluted simple green around with a handful of ball bearings.

gtmdriver · « **Reply #8 on:** August 19, 2016, 11:13:14 PM »

If you're using something like Por15 then their Metal Ready phosphoric acid wash will remove any flash rusting and leave a temporarily rust free surface for the liner to bind to.

b52bombardier1 · « **Reply #9 on:** August 20, 2016, 06:32:57 AM »

Hello,

GTMDRIVER wrote:

"If you're using something like Por15 then their Metal Ready phosphoric acid wash will remove any flash rusting and leave a temporarily rust free surface for the liner to bind to".

Exactly true. The phosphoric acid binds with the iron in the raw steel surface leaving behind a coating of iron phosphate. This coating is also very receptive to getting the urethane coating to stick. But still, I usually jump on pouring in the urethane liner as soon as my heat gun has gotten the inside of the tank dry - at least a 30-45 minute process for drying.

Rick

jamesw · « **Reply #10 on:** August 20, 2016, 01:19:13 PM »

Quote from: Scott S on August 19, 2016, 04:01:09 PM

Or just swish around a couple of ounces of Marvel Mystery Oil or two stroke oil until you're ready to put gas in it.

+1

This worked for me. After the vinegar soak, baking soda with distilled water soak/rinse, then I used acetone & motor oil to coat the tank, then finally sprayed a can of wd-40 to even further line the tank.

Powderman · « **Reply #11 on:** August 20, 2016, 06:37:30 PM »

Caswell makes a liner that is pretty good and prefers a rusty finish to adhere to.

flybox1 · « **Reply #12 on:** August 20, 2016, 07:02:25 PM »

No flash rust w prepnetch

mj1176 · « **Reply #13 on:** August 20, 2016, 09:44:48 PM »

+1 for POR-15, if you follow the instructions to the letter it works great for sealing pinholes. Don't seal the cap and allow any pressure to build until it's completely cured. Regardless of what liner you use, but especially if it doesn't include an etching product, you need to dry the tank immediately to prevent flash rust. I rigged up a hair dryer over my fill hole when I did my tank, let it run for a couple hours turning it over every 30 min or so to get any liquid out of the nooks and crannies.

somesuch · « **Reply #14 on:** August 21, 2016, 07:06:16 AM »

Quote from: Scott S on August 19, 2016, 04:01:09 PM

Or just swish around a couple of ounces of Marvel Mystery Oil or two stroke oil until you're ready to put gas in it.

This!

Don't create problems for the next guy, those tank liner things are headaches in the long run

somesuch · « **Reply #15 on:** August 21, 2016, 07:09:10 AM »

Disregard my post above, did not see that you have a pin hole in there

BomberMann650 · « **Reply #16 on:** August 21, 2016, 11:44:32 AM »

Redkote doesn't mind a bit of rust. The creator put a neutralizer in the formula, so they say.

SKOL · « **Reply #17 on:** August 22, 2016, 06:25:35 AM »

I filled mine up to the top with vinegar for 3 days. Rinsed several times with baking soda and water. Blew air in. Rinsed with Acetone. Blew air in it. Then dumped about a cup of marvel mystery oil in the tank. Swished it around. Everything looks good. I also don't have any pin holes. If I did, I would probably use prep'n'etch before using Redkote or POR15, that stuff really works.

carnivorous chicken · « **Reply #18 on:** August 22, 2016, 10:04:45 AM »

No matter what liner you are using, follow the directions provided with the kit, to the letter.

I use both POR-15 and Redkote, and will get around to using Caswell at some point because it also gets rave reviews. If you use POR-15 or Redkote properly, you won't be creating any problems for the next owner -- I have used both for years and have never had a problem, and have a tank with POR-15 in it that has stood up for 15 years so far, and a Redkote tank for about 10.

Sounds like you are already using Redkote, so there you go. As Bombermann650 has noted, Redkote doesn't mind a bit of flash rust. Contrary to what some others have said, however, unlike POR-15 (which requires a bone-dry tank before you add the sealer), Redkote does not require a completely dry tank. Redkote can be thinned with acetone, and if you swish around acetone prior to adding the sealer you can pour out whatever acetone will pour out and then simply add the Redkote without having to completely dry the inside of the tank. This is one of the reasons why Redkote is easier to deal with than POR-15 -- it's a 2-step process not a 3-step process.

Swishing oil or WD40 around in the tank isn't lining it and gas will wash that coating off eventually, leaving you susceptible to more rust in the future.

algophobe · « **Reply #19 on:** August 22, 2016, 05:16:39 PM »

Quote from: carnivorous chicken on August 22, 2016, 10:04:45 AM

No matter what liner you are using, follow the directions provided with the kit, to the letter.

I use both POR-15 and Redkote, and will get around to using Caswell at some point because it also gets rave reviews. If you use POR-15 or Redkote properly, you won't be creating any problems for the next owner -- I have used both for years and have never had a problem, and have a tank with POR-15 in it that has stood up for 15 years so far, and a Redkote tank for about 10.

Sounds like you are already using Redkote, so there you go. As Bombermann650 has noted, Redkote doesn't mind a bit of flash rust. Contrary to what some others have said, however, unlike POR-15 (which requires a bone-dry tank before you add the sealer), Redkote does not require a completely dry tank. Redkote can be thinned with acetone, and if you swish around acetone prior to adding the sealer you can pour out whatever acetone will pour out and then simply add the Redkote without having to completely dry the inside of the tank. This is one of the reasons why Redkote is easier to deal with than POR-15 -- it's a 2-step process not a 3-step process.

Swishing oil or WD40 around in the tank isn't lining it and gas will wash that coating off eventually, leaving you susceptible to more rust in the future.

I have a can of Redkote and PrepNEtch on hand... haven't opened it yet. the tank is being repaired at a radiator shop as we speak... I didn't want to gamble with the hole size since the manual for Red-Kote says it can seal up to 1 mm hole. Somebody's explanation about Iron phosphate as temporarily flash resistant makes sense.

The shop said they'll repair it but not coat it, the shop owner said they had a really good liner they used back in the day, but due to EPA regulations they can no longer use it... therefore they stopped lining them all together. Here's what my plan for the tank after I get it back:
1. do a short electrolysis de-rusting with sodium carbonate
2. wash out with soap and water
3. prepNetch
4. dry with air and acetone
5. apply Red-Kote

Question is whether acetone would reverse or wash off the iron phosphate protection... I'm getting PTSD flash backs from grad school with all these protocols.

calj737 · « **Reply #20 on:** August 22, 2016, 06:03:14 PM »

After PrepNEtch, line it. Don't use Acetone in between. Heck, you could probably skip the electrolysis stage altogether too when using PNE.

bochnak · « **Reply #21 on:** August 23, 2016, 08:45:00 AM »

I highly recommend using Caswell epoxy. I'm derusting a tank right now with vinegar and there are pinhole leaks showing up. The epoxy will take care of it and doesn't mind sealing over some rust. I try to remove the bulk of it.

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Author Topic: Issues with flash rust during derusting (Read 5969 times)