> I can add only one thing to the current phos. acid debate. I used it on a
> lightly rusted wire wheel and that wheel has since lost seven spokes. The
> fellow who rebuilt it asked if I had used Phos. acid on it, and when I
> said yes he handed the wheel back to me saying "Well, it will be cheaper
> to replace it now". TRuth or sales. I don't know, but it SEEMED to make
> the spokes very brittle.
Absolutely correct. Phosphoric acid is okay for mild steel pieces and
sheet metal but it should not be used on high strength alloys or chrome
plated steel because it causes hydrogen embrittlement (discussed
earlier). BTW, chroming causes this too but can be partly compensated
for by baking immediately afterwards. That's why chrome wire wheels and
chrome roll bars are not usually (ever?) allowed on race cars.
Roland
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