It is commonly referred to as "Pickling" a piece of metal to clean it.

Sherpa Doug

> -----Original Message-----
> From: Peter L. Peres [mailto:plp@ACTCOM.CO.IL]
> Sent: Friday, November 16, 2001 3:36 PM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: [OT]: Battery Corrosion and How to Get Rid of it?
>
>
> If you are desperate find an acid that is not strong enough
> to corrode the
> base metal quickly and dunk the part in it briefly. This does not work
> with plated contacts, unless the plating is a noble metal and
> you are sure
> it is intact (you can never be sure).
>
> The idea is that the strong acid corrodes a small amount of the base
> metal, restoring the surface, and any gunk or result of
> previous corrosion
> will be loosened and fall off (it is assumed that the gunk
> was previously
> scoured mechanically and weakened). The parts need to be washed
> immediately afterwards in running water or a large vat of
> neutral water
> (or slightly basic). With noble metals the noble metal does not get
> corroded at all, or extremely little (Gold, Rhodium, Platinum
> etc). Most
> contact metals do not react with bases so they can be washed in quite
> strong, hot NaOH solutions (caustic soda) at length.
>
> The method is used extensively for cleaning jewellery and small parts
> (even semiconductor chips during processing). The acid varies
> from HNO3
> 10% at room temperature to HNO3+H2SO4+HCL+H2O2 at 70C (Ouch).
>
> Peter
>
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