Corrosion of chromium plated tubular steel

Albert Griffith (a.griffith<-a t->rca< . >ac< . >uk) writes

>Has any one had any experience or know of any articles or
>information that is available regarding the corrosion problems with
>Chromium Plated Tubular Steel. I am especially interested in its
>application to furniture.

Although I don't remember any article or paper related to this
subject, I have some experience with this kind of material. Our
experiments have not been scientifically strict, but we have cleaned
chromium plated steel, removing the red corrosion stains (iron
oxides) using solutions of orthophosphoric acid. Sometimes a 10 or
15% solution of phosphoric acid in distilled water, applied to the
surface rubbing gently with a cotton swab has worked with good
results. Sometimes we have been forced to raise the concentration up
to 80%, because the dilute solutions didn't remove some stains. In
any case, the results, up to now are apparently good. Phosphoric
acid dissolves the red iron corrosion and leaves a film of iron
phosphate, which is gray and integrates visually to the chromium
surface, although it is not so glossy. As far as I know the film of
iron phosphate is more or less passive, but it might need a
protection varnish so you can be sure that corrosion will not
appear again. At least visually, phosphoric acid doesn't cause any
harm to chromium.

Well, this is just an idea, I hope it will be of some help. You
might need to carry out some experiments before trying it on
furniture, or ask your chemistry teacher what does he think about
this method.

Carolusa Gonzalez Tirado
Coordinator of the Metals Conservation Seminar
Escuela Nacional de Conservacion, Restauracion y Museografia
Mexico

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                  Conservation DistList Instance 10:88
                 Distributed: Thursday, April 10, 1997
                       Message Id: cdl-10-88-005
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