RE: [APML] Schmidt camera survives house fire

["Malcolm" <malcolmf@prodigy.net>]

Still off-topic, I would suggest the following for the chemistry of the
damage to the aluminum mirror.

When you burn wood, potassium & sodium oxides form in the ashes.  These
react with water to make KOH, potassium hydroxide & NaOH, sodium hydroxide,
or lye.  Boil this up with cooking fats and you have old fashioned lye soap,
the sodium/potassium salts of fatty acids.  Your great-great-grandmother
likely made soap this way.   Wood ashes are also useful in raising the pH in
acidic soils.  Where there has been a major brush pile burn, the pH may be
raised high enough to cause iron deficiencies in crops at that spot.

Aluminum is very susceptible to damage at high pH, dissolving nicely from
the hydroxyl ion (OH-).  It just loves to form AlO (aluminum oxide), giving
off H2, hydrogen, in the process.  [Al + OH = AlO + H]

Aluminum metal is extremely reactive and forms this oxide skin even in air.
Aluminum oxide is the stuff of sapphire and ruby, color depending on metal
contaminants.  This clear oxide skin is what makes aluminum seem to be rust
free.  Actually it 'rusts' very quickly.

You probably have similar damage to the aluminum tube, but as that is not a
micro polished surface, a microscope would be needed to see it.  Caustic
will also dissolve glass, showing up as an etch.  However, I suspect that in
your case, the solution was dilute enough, the exposure short enough and the
aluminum sacrificial enough to have avoided that damage.

Good luck with the Schmidt.

Calm Seas & A Prosperous Voyage
Malcolm

> -----Original Message-----
> From: owner-astro-photo@seds.org [mailto:owner-astro-photo@seds.org]On
> Behalf Of Robert Reeves
> Sent: Sunday, July 07, 2002 1:54 AM
> To: astro-photo@seds.org
> Subject: [APML] Schmidt camera survives house fire
>
>
> This is kind of off topic, but you might find it interesting.
>
> From the emails I have been receiving, litterally from around the world,
> many of you know that the central Texas
> area has been HARD hit by rain and flooding.  I am personally OK.  Some
> minor water washed into the detached garage, but it is dry now.  But a
> friend of mine was not so lucky.  Bryan Snow, the director of the Scobee
> Planetarium at San Antonio College, had his house truck by
> lightning and it
> was destroyed.  He and his family are safe, but almost everything
> they owned
> was burned or ruined by rain that cascaded through the now non-existant
> roof.
>
> Among the items damaged was his 8-inch Schmidt camera.  It was
> roasted, then
> drowned.  But it is still kicking!  I worked on it today and will continue
> cleaning it tomorrow, bit I am confident that his Schmidt will be
> ready for
> service by tomorrow night.
>
> I have posted some photos of it on my web site at
> www.robertreeves.com/scorched.htm
>
> The 8-inch Schmidt is a tough cookie.  I am impressed that it survived in
> such good shape.
>
> Robert Reeves                      reeves10@swbell.net
> 520 Rittiman Rd.                   www.robertreeves.com
> San Antonio, Texas 78209    210-828-9036
> USA                                     29.484  98.440  200 meters
>
>
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