Ian,
Am no chemist but have used Sodium Bisulphate (meta too I think) for
broken drills etc in gold, silver, and aluminium. For aluminium somewhat
dilute nitric would be faster but much harder to obtain these days and not
nearly as safe from a handling aspect. For gold and silver it saved my
reputation on a number of occasions in commercial shops.
Jeff
* REPLY SEPARATOR *
On 4/5/2007 at 11:37 PM Ian Foster wrote:
G'day Jeff, Andy, et al.
I'm not quite sure by your comments whether you have used Sodium
Bisulphate to extract broken taps. If you have then that
substantiates my assessment that it is the sulphate ions which do the
work. Being a bisulphate the iron ions do not need to displace the
sodium ions to form sodium hydroxide (corrosive to aluminium), they
just neutralise the solution forming iron sulphate and sodium
sulphate.
In my discussions it can sound like the ions making up the repective
salts just combine in solution, this is not the case. The solution is
just a soup of dissociated ions which don't come together until they
become insoluble, either by their inherent properies (as for
insoluble salts like calcium carbonate) or by concentatration which
leads to crystalisation (as for common salt, sodium chloride).
In Oz you can readily obtain Sodium Metabisulphate for sterilising
home brew gear and for fruit preservation, Ive used it myself in that
role. The metabisulphate may have too high a pH to be effective.
Andy! Here's another chemical to test. Safer than making Gun Cotton!
One good turn deserves another.
Regards,
Ian
--- In 7x12minilathe@..., "Jeff Demand" <jdemand@...>
wrote:
Ian,
For some more info to confuse the chemistry freaks... the
jewellery
pickle is labelled " Sodium Bisulfate". The PH down might be
a 'sodium meta
bisulfate' but it is reported to be a cleaner (and cheaper)
replacement for
the jewellery standard Sparax brand. A totally different chemical
than alum
but it has worked for me in the past and is always available in my
studio.
Jeff
Be sure to check out for small mills and
lathes.
Yahoo! Groups Links
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