Rust removal by Electolysis

[ed_h]

I've used just about all of the de-rusting methods discussed here. Electrolysis worked fine, but in my experience, it was no better than other methods that I consider simpler. My main approach these days is phosphoric. It's simple, effective, cheap, safe, and non-toxic. It also leaves a surface coating of iron phosphate that offers some protection, and is a good base for paint.

Some time back, I did a quasi-scientific test of phosphoric acid vs EvapoRust. Performance of these two in terms of effectiveness and speed was just about a wash. This (for me) puts phosphoric on top on grounds of cost.

On the topic of hydrogen embrittlement: It is a real issue, but only for high strength or hardened steels, and even for these, there are well known processes to mitigate the problem.

Ed

 

[Mister Ed]

I have always heard the hydrogen embrittlement deal more related to the more aggressive acids ... HCL etc and also more related to springs. Right? Wrong? Maybe I'm wrong but, I always considered phosphoric as fairly safe, since it pretty much stops acting on the iron (I'm usually dealing with cast) once the rust is removed/converted and you have the iron phosphate coating left.


Now, if one was to play around with EDTA on some rusty, nasty, been in a junk pile for 40yrs, windmill parts ... which EDTA would you use and what kind of concentration? Is EDTA Tetrasodium the place to start? How much per gallon of water?

Without looking too hard, I can get 5lbs delivered to the house for $40. If I only need to mix 1lb/gallon of water ... that would be similar to buying Evaporust for $8 gallon. If I only need to use a half lb/gal ... you get the picture. Maybe Evaporust has some other "stuff" or different chelating compounds in it ... but if the EDTA works. :thinking:

I'm thinking that I'm onto what Franz was meaning by "over priced Evaporust".

 

[f350ca]

I'll have to respectively disagree on the opinion that hydrogen can't enter steel unless its melted. High strength/high carbon steels exposed to hydrogen sulphide in even relatively low concentrations will be affected. The hydrogen attaches to the carbon atoms and stresses the matrix making it brittle. Low carbon steels are not however affected. In the oil and gas industry where well head equipment can be exposed to H2S it is only made from mild steel. I was involved in oil well electrical logging, our standard cables were made with high strength steel armour, exposure to even 2% H2S in fluid solution would cause strands to snap as they flexed over the shiv wheels, at 10 or 15% cables would snap under straight tension.

Greg

 

[f350ca]

The molasses treatment is working, only been about 6 days from a fresh mix.

 

[f350ca]

Guess its been 10 days in the bath. Pulled the parts out today, a bit of a rub with the wire brush in a few spots and a rinse under the tap. Pretty labour unintensive.

 

[xalky]

It looks really good though! )

 

[Tony Wells]

Told ya! Cheap, effective, safe.....but slow.

 

[f350ca]

The blower parts got a rattle can paint job and assembled.



Greg