[meteorite-list] Etching solution

[MexicoDoug]

Craig,
Let me add (the message actually got away before being finished as I 
write piecemeal and then send) that as far as etching it works fine, 
but if you look at the series of alcohols, methyl (bp = 65 C), ethyl 
(bp = 78 C) and isoproply alcohol (bp = 83 C), methyl alcohol 
(methanol) is by far the safest until you get a lot of experience 
working with these under a hood.  "Ethyl nital" is mildly flammable in 
and Isopropyl nital is pretty dangerous since if can blow up in certain 
conditions that aren't difficult to arrange.  Nothing to do with the 
etching results which are left to trial and error, but rather the 
safety which I should have mentioned.

While all the alcohols work fine, keep in mind two of the factors you 
are working with are miscibility/penetrant ability and vapor pressure.  
Vapor pressure you can estimate by boiling point - lower bp is a higher 
vp.  The higher vp the quicker it will evaporate out, so methanol would 
seem to have the advantage, thought it might form some azeotropes and 
stay in longer, as could the rest without looking this up (no time at 
the moment).

To the series of three common alcohols you could just add water bp = 
100 and consider it almost as a continuim and play with the you like 
which will influence drying time among other important parameters.  I 
use methanol and later rinse with ethanol (cheaper for me), which is 
the reverse of good drying practice I would think, but half of the time 
I just use the diluted acid at 2 - 3 N.

Hope that was a better answer, sorry for not finishing the first
kindest wishes
Doug


-----Original Message-----
From: Craig Moody <meteoritesnorth at hotmail.ca>
To: mexicodoug <mexicodoug at aim.com>
Sent: Thu, Jan 26, 2012 9:42 pm
Subject: RE: [meteorite-list] Etching solution


Much appreciated Doug, Thank you!  I have lots of 99% around.

Craig