On Nov 8, 11:56, Douglas Quebbeman wrote:
> > > One possible problem, Sodium Hydroxide < .5% could be damaging and
> > > corrosive to metalic parts.
> >
> > About the only common material that sodium hydroxide will attack is
> > aluminium, and then only when concentrated or exposure is reasonably
long;
> > it has no effect on copper, steel, etc.
>
> Yeah, I've relied on this as a way to make satin-finish aluminum
> front panels for equipment. As the reaction progresses, the NAO2 (?)
> solution has to be preiodlically replaced. It generally took me about
> two days to get the desired look.
Sounds about right. Depends on the concentration and temperature, of
course, and also the fact that NaOH readily absorbs CO2 from the
atmosphere, turning into Na2CO3 (sodium carbonate, washing soda) which
doesn't have much effect on aluminium. In fact, NaOH and KOH are so good
at that, that they're used in atmospheric scrubbers.
--
Pete Peter Turnbull
Network Manager
University of York
Received on Thu Nov 08 2001 - 14:26:06 GMT