[meteorite-list] Etching solution
MexicoDoug
mexicodoug at aim.com
Fri Jan 27 03:11:05 EST 2012
"explosive"
Definitely caution when playing around with corrosives is of the first
order...that said,
sure, ethanol is a racing car engine fuel and under the right
conditions can combust; But people drink it even straight...
Many things we do have risks associated with them some very serious and
definitely we must respect all reagents especially corrosives like
nitric acid. For example, many people enjoy fireworks. Yet, fireworks
are explosive and dangerous if you put them near sparks or heat,or try
to light them with a charcoal grill. And obviously gasoline combusts
too yet mechanics and Dads everywhere use it to clean hands and metal
parts and also have arc welders nearby. Or sulfuric acid inside a car
battery - don't get it on your bikini when working on the car! If you
are going to use anything, it needs to be done with respect and a quick
read of the MSDS of whatever chemicals you are using... (and don't
trust everything you read on a discussion l;ist posted at 3 AM)
It is not a good idea to have concentrated nitric acid and ignore the
label, for example and my heart goes out to Anita on that. Depends the
kind of person you are. When I make my smoothie in the morning I use
fresh cherries as one of 18-20 ingredients and a preparation that takes
an hour. It's life threatening if I accidentally put a pit in my
blender (which can easily liquify meteorites, it's so powerful) due to
the specialized needs of a family member who cannot eat. So I double
count the cherries first, count the pits as I punch them out, and then
count them once again when I dispose of them. No shortcuts, All common
sense!
Bart Simpson's pet python once made nital in an episode of The
Simpsons, which is amusing if you haven't had a bad experience you
can't laugh about.... I think the writers were Caltech rejects that had
to go to MIT and have to do this to humor themselves, this wasn't the
only snarky chemistry episode.
(episode: Stop or my Dog will Shoot!)
Here's the link:
http://video.i.ua/user/810302/8185/35583/
it take a little time to stream, but once ready the scene is at the
17:49 minute:seconds mark.
... and that' why in my summary which I did much too quickly to be
complete, I suggest that you use water, that is to say, NitH20,. or as
it's commonly known just dilute Nitric Acid, rather tha alcohols to
develop your method. Nothing wrong with water, it is really getting a
bum wrap and it is GRAS ;-) It is what everyone that is using FeCl3 is
using as a diluent, too. For the HNO3 the 3.0 N concentration works
best for me. Absolutely no need to buy concentrated acid and you can
avoid all the issues of what to add to what and no need for Hazmet
backup. You can buy it already diluted, get the same benefit of a
nitric acid etch (alcohol doesn't etch, it's only a carrier and
diluent). Just crank up the oven to the higher end of a safe drying
temperature. That's the only real benefit of alcohol in my opinion -
it allows a cooler drying which can povide a nicer (lower oxdation
residue on the virgin etched surface, but now we are staerting rally to
split hairs...IMO.
Speaking of diluents, there's no reason nital (alcohol) is special as a
diluent. Besides water, I'm suspecting Nitric + acetone (Nitkeytone ?)
and any number of other solvents would work fine if not be hiding a
secret for even a better etching solution. Sure acetone is flammable
and can give you the willies too, you can't win but that doesn't stop
women who understand the chemical they use from putting it on their
fingernails ;-) granted not with acid, though I bet some do
inadvertantly mix it with salycilic acid solution when disolving excess
skin ;-), which if not used properly could chemically remove a lot of
flesh ...
Kindest wishes
Doug
-----Original Message-----
From: Mark Grossman <markig at westnet.com>
To: MexicoDoug <MexicoDoug at aim.com>; meteoritesnorth
<meteoritesnorth at hotmail.ca>; meteorite-list
<meteorite-list at meteoritecentral.com>
Sent: Fri, Jan 27, 2012 12:32 am
Subject: Fw: [meteorite-list] Etching solution
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" <markig at westnet.com>
To: <mexicodoug at aim.com>; <meteoritesnorth at hotmail.ca>;
<Meteorite-list at meteoritecentral.com>
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" <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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