Cleaning rust from inside of tank...chemists step inside;)

[Mike B]

I have about 3-4 gallons of Hydroflouric (sp) acid left...we used to mix this with water in a weedsprayer and spray on all my dads polished Aluminum on his Peterbuilt...let it sit a bit, then rinse off.

Anyway..it's labled as "Aluminium Brightener" the jug says "mix up to 50-1"...it also says does not exceed 60% strength (I take this as it sits in the jug).

Anyway, thought on using this to clean the rust inside a fuel tank?

I'd thought about mixing it maybe 20 parts water, and 1 part of the solution (would actually be about a 40-1 mix of water to HF).

Thoughts?

[47Merc]

I'm no chemist but I know at full strength it makes a great soldering flux on copper and stainless steel. I would have thought you wouldn't want to dilute it too much to dissolve rust.

Why dont you mix a few small amounts at different ratios and try it on some rusty scrap metal and see what the results are before you put it in the tank.

[Mike B]

Good idea...in fact, I have some rusty coffee cans that can become test subjects!

[mrtexas]

I'm a chemical engineer who took plenty of chemistry. I'd stay away from HF. It is a very toxic stuff, especially at high concentrations. It will eat up glass. Same chemistry as calcium so if you get exposed to it say thru your skin, it will eat up your bones. In some refineries the high test stuff is used as a catalyst and the operators have to suit up in a space suit to walk thru the unit. Look up the HF alky process for a real scare.

For the inside of a fuel tank I'd get 5 gallons of phosphoric acid (Ospho) at a hardware store for about $100 and fill er up, then tip the gas tank on it's side and soak for a couple days and then tip it on the other side. It eats up the rust and leaves a hard black surface. Ospho is very safe even though it is 60%. If you have a cut it will sting a little but that is all.

[Mike B]

This stuff we have is sold as "Aluminum Brightener", normally marketed to Trucks and fleet use, I'll get the brand name and more info on it for you.

I do understand that HF is pretty nasty, but this stuff must be tamed down for public use (I suspect).

Thanks MrTexas

[jake197000]

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mrust,that was a great response.thats one thing i love about old cars,it brings people of all walks toghrter..we all have many years of life experiance.well moat of use.being most v8 guys are old.the young guys have the smarts.we have th experiance.we learn from each other. thanks.

[jake197000]

sorry,,,,, mrtexas.guess im old.

[B-O-B]

You can buy a gas tank coating kit from Eastwood for less than $100.00. There are 3 qts of liquid. A cleaner/degreaser,primer& coating/sealer. Did my 34 roadster tank & it is setting for the summer with the modern type ethanol fuel & will see how good it stores when I get back to it this fall. I did add MMO & sta-bil. They state it will holdup to ethanol fuels.

[1952henry]

Originally Posted by Mike B

This stuff we have is sold as "Aluminum Brightener", normally marketed to Trucks and fleet use, I'll get the brand name and more info on it for you.

I do understand that HF is pretty nasty, but this stuff must be tamed down for public use (I suspect).

Thanks MrTexas

I have some cleaner that is mostly phosphoric acid but contains HF as well. Doesn't bother the skin much, though I use gloves.

[Mike B]

Here's what's the labels say.

thanks all, see what you think.
Click on the pics to enlarge.

[Mike B]

Originally Posted by B-O-B

You can buy a gas tank coating kit from Eastwood for less than $100.00. There are 3 qts of liquid. A cleaner/degreaser,primer& coating/sealer. Did my 34 roadster tank & it is setting for the summer with the modern type ethanol fuel & will see how good it stores when I get back to it this fall. I did add MMO & sta-bil. They state it will holdup to ethanol fuels.

Yes, I know about the kits, have heard good things about Eastwoods and Por 15's, unfortunately I'm on a serious budget crunch right now, but still want to make some progress.

[texas webb]

Originally Posted by B-O-B

You can buy a gas tank coating kit from Eastwood for less than $100.00. There are 3 qts of liquid. A cleaner/degreaser,primer& coating/sealer. Did my 34 roadster tank & it is setting for the summer with the modern type ethanol fuel & will see how good it stores when I get back to it this fall. I did add MMO & sta-bil. They state it will holdup to ethanol fuels.

B-O-B:Make sure you use marine sta-bil.Ethanol Shield is available at good
lawn mower shops and home depot.Good product.

[AnthonyG]

Just my experience with cleaning an old tank. Per threads researched on FB I filled the tank with white vinegar for a month agitating frequently, rinsed thoroughly with baking soda and water solution to stop acid reaction. Then rinsed and agitated a lot with water then dried with shop vac and hair dryers. All looked good with bore scope but in trying clean tank before coating I couldn't get all the partially dissolved rust out of the baffles before coating no matter how much I agitated and rinsed. Spoke to professionals who do the cleaning and coating for you ( $200 ) and they said during the cleaning and agitating then coating process they put a couple of strategically placed faily large holes to make sure all debris undissolved and dissolved gets out then they repair the holes and coat.

I gave up and bought a new steel stock config tank from Tanks Inc. through Williams Street Rod for $180 and all is great.
Just trying to save you some agg's.

[B-O-B]

texas webb
Thanks ;
Marine grade is all I use, better buy than regular. I also make sure that the top underside of the tank is coated as some have stated that condensation forms there & causes rust. I tried the vinegar treatment & was not happy so I bought the Eastwood kit . In the past I have also used the ospho treatment I know it also works.
A side note if I may: When I was commercial fishing for living a fellow had a steel boat that was rusted & in need of a paint job really bad. He was different type so to speak,anyway he covered completely covered his whole 26'+ maybe 30' boat with ospho & left it that way without any coating over it. I cannot remember the condition of it when I quit fishing & supposedly retired, hmph!!!! Retired is a joke as I worked harder than ever building houses,shops & cars.

[TJ]

AnthonyG makes a good point. If you spend a bunch of money on an old tank and it doesn't work, it's money you could've spent on a new tank. You have to face the fact that old rusty tanks do not have the same structural integrity that comes with a new tank.

[texas webb]

Retirement is nice,but there is never a day off.

[B-O-B]

Retirement is nice,but there is never a day off.
Right on & the pay is way less.

[Mike B]

Here's some before and after shots (thanks to 47merc's Idea) of an old coffee can I had.

I mixed this about 6 inches of water, and a 1/2inch of the Al. Brightener I have and let it sit out for just under an hour.

I've since poured it back in the can and will let sit longer to see if things improve on the heavier rust at the bottom of the can.

I'll be checking about every hour to see how it's going.

[Ross F-1]

Originally Posted by mrtexas

I'm a chemical engineer who took plenty of chemistry. I'd stay away from HF. It is a very toxic stuff, especially at high concentrations. It will eat up glass. Same chemistry as calcium so if you get exposed to it say thru your skin, it will eat up your bones. In some refineries the high test stuff is used as a catalyst and the operators have to suit up in a space suit to walk thru the unit. Look up the HF alky process for a real scare.

....

I can't believe that is available to the public! I worked in the semiconductor industry, where it is used to etch silicon. It is about the most feared chemical in plants where there are some other truly nasty chemicals. At one plant a guy got a small amount on his arm, and in a matter of hours he lost most of that arm. It bored in thru his skin and ate up the bone. This despite immediate treatment. I would get rid of it ASAP!!

[Mike B]

Hey Ross, I understand your concerns.
I did a lot of searching on wha I have (the Al Brightener) and the vast majority of truck wash stops use this same/similar product.

Apparently is also has Hydro Flouride and a host of proprietary inert (believe it said inert) acids.
This is not just straight HF mixed with water to dilute it.

Anyway, I let my roughly 12:1 mix sit another hour, the can is dead clean...I also took that particular 12:1 that was in the can, and made it roughly 24:1 and poured into a worse can...been soaking a few hours now and will check it this evening.

I'm not promoting to anyone to go out and buy this stuff, but since I had it...and have used it before without issues on Al, my main concern was would it get rid of the rust, and it sure seems to do the trick.

I'm going to play with it for a bit and find a nice, weak solution, that won't take days of effort to do the job.

After rinsing the first can, I'm letting it sit to see how long it takes to flash rust...pretty hot and dry here BTW, so think it'll be good for quite awhile.

Thanks all.