[meteorite-list] Etching solution

From: Mark Grossman <markig_at_meteoritecentral.com>
Date: Thu, 26 Jan 2012 23:40:53 -0500
Message-ID: <43BC32B6B4DB451CB21709D648301AA9_at_QED>

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" <mexicodoug at aim.com>
To: <mexicodoug at aim.com>; <meteoritesnorth at hotmail.ca>;
<Meteorite-list at meteoritecentral.com>
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 <mexicodoug at aim.com>
> To: meteoritesnorth <meteoritesnorth at hotmail.ca>; Meteorite-list
> <Meteorite-list at meteoritecentral.com>
> 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 <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
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Received on Thu 26 Jan 2012 11:40:53 PM PST