Dealing with Extreme Surface Rust

[wayne sheldon]

I have used an electrolysis to remove rust quite a bit, with mixed results. It has done an incredible job sometimes, not so good others. One issue is that the electric current follows paths of least resistance in the solution. That means some paths, longer, bad angles, etc, do not de-rust as well as nice open direct paths. Moving anodes around can help some, but some corners just don't clean as well as other areas. I cleaned a cylinder block once (being very careful not to affect the bearings in the block). The only way to clean inside the cylinders was to put the anode into each cylinder individually. As I mentioned, bearings, soft metals can also be "plated away" by electrolysis just like it can by mild acids (I experimented with that myself before cleaning).

I also had some issues with the battery chargers I used to power the electrolysis. I don't think they were quite adequate (but they were what I had available).  I also found that keeping the anodes clean was very important. The gunk that builds up on them cuts the efficiency a lot. The small tank I used is outside, and with the chemicals involved, corrosion of electrical connections became a pain in the wazzoo. I brazed and soldered critical connections and still had problems.

 

I desperately NEED to get back to work on my model T project (family got in the way and I haven't worked on it in nearly four years now  ).  First up is rusty fenders and side aprons. I think I will have to try molasses.

 

As for acids. Muriatic acid is NASTY stuff. I have used a fair amount of it myself.  Friends and I refer to it as the "fume bath" because of the nasty fumes it creates.  The fumes alone can be DEADLY. Great care must be taken. Open space, you, and nothing valuable downwind. But it can remove really bad rust. It also has a nasty habit of accelerating new rusting when something is cleaned with it. Stopping the new rust can be almost as difficult as dealing with the old rust would have been.

Phosphoric acid and/or solutions are much milder, but still pose some risks. Phosphoric solutions such as "Metal Etch" (if it is even still available) do help to control new rust and help paint to adhere to metal. 

 

As with many such things. Pay attention, listen, learn, and be careful.

[R Walling]

9 hours ago, mike6024 said:

I am inclined to think that a molasses solution is a mild organic acid; until someone proves or demonstrates otherwise.

 

Coca Cola can clean things, and it is acidic. Anything below pH 7 is acidic.

 

(The average pH of Coca-Cola, Pepsi, and other colas is 3.4.) Carbonation combined with the acid can dissolve the metal oxides and remove tarnish from copper, brass and other metal alloys. Citric acid is known to remove the stains. Phosphoric acid is commonly used for rust removal

 

http://greencleaningproductsllc.com/mythbuster-science-of-cleaning-cleaning-with-coca-cola-effective-green-cleaning-products/

 

 

It is not an acid. It works by taking away the oxygen from the iron oxide.  (rust)  It never affects the solid steel.

[Dandy Dave]

Although I have done some things with chemicals, I have done most of my cleaning with blast media. Sand, Glass beads, and the like. Speaking of chemicals, I have used easy off or other oven cleaners to clean dirty engines, transmissions, other parts . Degreases and also removes older non acrylic paints. Basically lye in a can and does the same thing as tanking engine and other parts in a machine shop. Works well on old tractors that are both greasy in areas and old faded paint and rusty in others. Just spray it on, wait 10 to 20 minutes, then high pressure wash the stuff away. Get the rust by sand blasting what is left away. Dandy Dave!