Did a quick search on the internet. Read this tale from the Meteorite
Association of Georgia regarding the hazards of mixing nitric acid and
ethanol: http://www.meteoriteassociationofgeorgia.org/article-052007.htm.
Mark
Mark Grossman
Meteorite Manuscripts
----- Original Message -----
From: "Mark Grossman" <[email protected]>
To: <[email protected]>; <[email protected]>;
<[email protected]>
Sent: Thursday, January 26, 2012 11:40 PM
Subject: Re: [meteorite-list] Etching solution
I don't know all of the details of the etching process, but a word of
caution - mixing concentrated nitric acid with ethanol can result in an
explosion and a fire. I've witnessed the results of the reaction when
someone inadvertently mixed the two in a lab years ago.
Mark
Mark Grossman
Meteorite Manuscripts
----- Original Message -----
From: "MexicoDoug" <[email protected]>
To: <[email protected]>; <[email protected]>;
<[email protected]>
Sent: Thursday, January 26, 2012 11:23 PM
Subject: Re: [meteorite-list] Etching solution
PS - if you don't have a hood or other exhaust, the methyl alcohol could
also be dangerous becasue the liver breaks it down into toxins and you
will inhale some of it. That's another reason why I use ethanol in the
oven, and frankly much more important a reason than saving a few pennies
;-) You can consider the residence time of the toxins in your system to
be as long as a week, so if your are doing etxching all day long,and are
using methanol nital you definitely need a very well ventilated place,
and methanol is sneaky worthy of a CSI episode of an innocent who done it
since the syptoms and critical second hit can be stealth and barely
naseaous for the first.
I know you didn't ask about methyl alcohol, but its good to see the 4
common solcvent benefits/liabilities side by side, at least my take on
it. Anyway, you can see why ethyl alcohol iis usually preferred. I just
checkethe azeotrophes andisopropyl is only 2.3 C above ethanol mixtures
so its ability to remove water would be very similar in the oven, the
last thing to look up to decide theoretically approximating the
penetrating ability as related to the surface tension of the alcohol
(just a guess) what is the bestest alcohol would be to check the surface
tension. I just did and all three alcohols are nearly 4 times that of
water and within 5% o each other, so I would think that on penetrating
ability they are probably all tied and would argue all factors considered
ethanol is best since the worst you get is a standard hangover in
standard use conditions, and to get a freak explosion from EtOH mixtures
with acid is minimal compared to isopropyl.
Ferric chloride of course doesn't have the toxicity not flammability, but
it stains like heck and with proper respect for the reagents plus a
little experience, like everything else the risks are minimized. That's
another reason to start with dilute nitric which I highly recommend until
you have the bugs worked out of the etching "assembly line", ie, method
you find best for your work.
Good luck,
Kindest wshes
Doug.
-----Original Message-----
From: MexicoDoug <[email protected]>
To: meteoritesnorth <[email protected]>; Meteorite-list
<[email protected]>
Sent: Thu, Jan 26, 2012 10:30 pm
Subject: Re: [meteorite-list] Etching solution
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 <[email protected]>
To: mexicodoug <[email protected]>
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
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