rust removal on oversized objects

[double R]

someone mentioned this to me but can't remember...is there such a process which you can get large objects like auto body panels or chassis dipped in a tank of rust removal chemical/solvent?

anybody have an idea of how much this cost?

[Franz]

There are 2 processes you can use, one is electrolytic de rusting, and you can do it yourself.

Rust can also be converted to an impervious coating using either a tannic acid or phosphoric acid process.

If you want to remove paint, grease and crud, you can dip panels in a tank of hot caustic soda, NASTY process.

[Rocky D]

There is a paint that will combine with the rust to make a solid coating, that can be painted over after....but I don't know what it's called....I think Rustoleum has it. Ya paint right over the rust.

[theshop]

i have seen a product called corroseal in the back page of boats & harbors

their website is www.corroseal.com

play safe
theshop

[Bill H.]

double R, Auto body folks use Ospho, a brush on liquid which I believe turns rust inert. My experience involved treating some light surface rust on a car door. The water like Ospho was brushed on using a disposable brush, this turned the orangish rust black. I followed with an automotive primer then topcoated. Looked terrific when done, i.e. the former spots were invisible on the panel. This was done on a friends El Camino which he sold about five years later. The Ospho we purchased was in a plastic jug about quart or half gallon sized. I would imagine not practical to dip a car body but was as easy as wetting a surface and waiting for it to dry. Try a google search for Ospho, I got lots of matches. -Bill

[CPB]

I've used muratic acid mostly as a last resort to clean rusted parts that are hard to get with a wire brush because it's fairly cheap and seems to work pretty good. I always wondered if anyone else does the same or if I'm the one and only dummy doing it this way. I do take precautions to protect myself especially my eyes, lungs & skin. The first (and last) time I took a wiff of that stuff it about knocked me on my ***. Also use a fan if the wind isn't blowing,
CPB

[harold]

The Rust-Oleum product is Rust Reformer. Clean off any flaky metel and paint the stuff on ( use a throw away brush) It converts the rust to a primer you can paint over. Its available at Home Depot and other such places. There was another one called rust converter which I liked better, problem was it worked too good and it was pulled off the market.

[lranch]

Ditto on Ospho, got a bottle right here, contains Phosphoric Acid. Works good, used some on the Urban Assault Vehicle, you can tig across it, if necessary.
Ditto on Muratic Acid. Works very well (cheap, can fill a 55gallon plastic barrel for a few bucks.) Added some badges to a 2 of my harley tanks and used the dip to clean inside and out. Couple of hints: Works fast on braze or silver solder joints, keep an eye on them. Rinse well and plan to prime same day, repeat. Also Muratic doesn't simply render rust inert, it eats it! That is, if surface has deep rust you will have deep holes or depressions. Anyway Good Luck.

[Franz]

OsPho, and about 50 other products are a phosphoric acid process that converts Iron Oxide to Iron Phosphate or magnetite. Some of these products contain polimers to add ductility to the magnetite coating. The problem with all products that polimer products is that they do not penetrate deeply into the rust.
LockTite Convert is also a phosphoric process with magnesium and zink in the solution. These products work better than Ospho, when they are allowed to wet sufficiently to fully penetrate the rust and convert it.
Iron Phosphate itself is an excellent primer for painting, and does NOT require a primer layer between it and the enamel coat.

Muriatic Acid does eat rust, no doubt about it. It also is nearly impossible to fully neutralize, so the usual result to muriatic derusting is the formation of more rust.

Electrolytic derusting removes the rust, and works even to the level of molecular rust in microfissures in formed sheet metal.
There are no hazardous chemicles to deal with, and the only potential problem is outgassing from the tank of Hydrogen and Oxygen, at levels similar to charging a lead acid battery at the same rate of current flow used in the tank.
In terms of cost, electrolytic wins over sandblasting by a factor of 100 to 1. Electrolytic removes as much rust as the Muriatic process if not more, and doesn't require neutralizing.

[Rocky D]

Man! this is a total goldmine of information! Thanks guys

[CPB]

Check out this site on electrolytic derusting. It goes from A to Z on the subject. I think I'm going to give it a try. CPB http://www.stovebolt.com/techtips/ru..._derusting.htm

[Scott V]

Rocky D.
We have a couple of guys over at the Chaski web board like Franz,One is Harold,and another is Forrest.They can back up all their statements with facts that will make you head spin.They all have one thing in common is they know their stuff,and can get a little onery,when you think you Know it all.I find that very refreshing,because it kind of keeps your head out of the clouds,or somewhere else.

Rocky D,I also know that you know what your talking about also,just a little more easy going way of saying it.
I kind of like both styles for a change of pace.

[double R]

Franz...you mentioned that the hot caustic soda process will remove paint, grease and crud...i just want to double check whether it'll remove rust as well...if so can you give me an idea of how much it'll cost me to get a jeep frame dipped at a place that does it?...also if anyone knows any good shops in the los angeles area that does this process...thanks

[Roger]

Thread Rust Prohibitive at sci.engr.joining.welding news group had good info on using Phosphoric Acid to derust. Said that adding Magnesium to Phosphoric Acid and by boiling rusty part in resulting solution you have parkerized the metal.

Another thread Electropolishing / Passivation of Stainless steel welds is of interest.

Use google groups search to find and read those thread topics.

[Franz]

RR the hot caustic process won't do squat for rust, but I guarnatee you that if you dip a jeep frame in hot caustic and paint it, you'll be pi$$ed for years to come.
The caustic will get between the rails and cross members, and leach out slowly destroying the paint.
If it was mine, I'd make a pool out of poly and some 2x12 boards, fill it with water and soda, hook up the battery charger and cook it clean of rust.
Then, I'd pressure wash, and let it surface rust a day or 2, and then phosphoric acid treat it. Cover with poly so the acid works longer. Then paint it with chassi paint, and you'll be happy for 20 years.
We let brand new machines & trailers rust just so we can phosphate them, and have machines it was done on 20 years ago that still look good.
You're on the wrong coast for me to know about local shops.