[sdiy] products for rust removal - the joys of phosphoric acid

David G Dixon dixon at mail.ubc.ca
Fri Dec 23 01:56:53 CET 2011

> A better way to remove rust, is to soak the rusted object for 
> a couple of weeks in a mixture of molasses with four pars of 
> water. This is what the car restoration guys do.
> I didn't believe it would work, but I tried it with a blob of 
> rust that I found on the roof - it turned out to be an old 
> double screwdriver.
> Apparently the molasses has a compound that chelates the iron 
> in the rust. 
> The advantage is that the metal iron is not attacked at all. 
> Cheapest place for molasses is the stock feed store. Most 
> expensive is the organic health food place.

Interesting.  Many organic acids (citric, malic, tartric, etc) chelate iron.
In fact, I have a patented process for nickel recovery from basic ores
containing natural nickel-iron alloys which uses citric acid in the mix to
chelate the iron as it dissolves and prevents it from re-precipitating back
out onto the leaching surfaces and stopping the leaching reaction.  I'm not
sure what the organic acids in molasses might be, but this certainly sounds
feasible to me.

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