[meteorite-list] Etching solution

From: Mark Grossman <markig_at_meteoritecentral.com>
Date: Fri, 27 Jan 2012 18:20:08 -0500
Message-ID: <9A72F43097D647E9B7BF82465E2BCBE5_at_QED>

Hi,

Couple of thoughts.

Mark's Law:

If you're standing in the exact same spot as someone else when a mixture of
nitric acid and ethanol explodes, the sensitivities of the two individuals
to harm are always the same. :-)

Both nickel chloride and nickel nitrate are soluble nickel compounds, and as
far as carcinogenicity goes, the American Conference of Governmental
Industrial Hygienists and the International Agency for Research on Cancer
group the two compounds together. As far as I am aware, there was no
singling out of nickel chloride as being 15 times more carcinogenic than
nickel nitrate - you indicated both are products of etching - one from
ferric chloride and the other from nitric acid. The insoluble oxides of
nickel are more carcinogenic, but that's not the compounds you are referring
to. Would appreciate a reference for the nickel chloride being 15 times
more carcinogenic than soluble nickel nitrate.

Similarly, would appreciate a reference to isopropyl alcohol being more
dangerous to use for etching with nitric acid than ethanol, under the same
set of conditions. Why is isopropyl alcohol more prone to a "freak"
explosion or "blow up" than ethanol? Explosions with concentrated nitric
acid and ethanol are well-documented.

Now I am not relying on Wikipedia as an academic reference, but I think the
information contained on the webpage is worthy of discussion and/or
criticism. See http://en.wikipedia.org/wiki/Nital and the mention of the
hazards associated with 5 and 10 percent solutions. This information
appears to come from Bretherick, which is a pretty good chemical reference
that I have used in the past (see
http://www.ab.ust.hk/hseo/tips/ls/ls005.htm).

Reading Material Safety Data Sheets should always be required - but realize
that many are inadequate and often do not list or spell out the safety
precautions which should be employed.

A lot of technical information was contained in the last few emails, and if
we all agree that respect for chemicals is critical, then it would be useful
to confirm the facts.

Thanks!

Mark

Mark Grossman
Meteorite Manuscripts


----- Original Message -----
From: "MexicoDoug" <mexicodoug at aim.com>
To: <nf114ec at npgcable.com>; <meteorite-list at meteoritecentral.com>
Sent: Friday, January 27, 2012 1:02 PM
Subject: Re: [meteorite-list] Etching solution


> Hi Jim,
>
> My respects to all the ferric chloride lovers out there and especially Ron
> Hartman, bless him. A blanket statement of a "better etch" is pretty
> meaningless. I recall asking Arcady who had all the Seymchan several
> years back why all of his specimens were etched so deeply that they looked
> like someone chiseled the etch into them and then put on a matte
> clearcoat. He said, the customers prefer a deep etch. I thought it was
> butt ugly (not to mention a more discrete etching such as by mild nitric
> acid's slow action introduces far less nucleation sites for oxidation).
> There are so many factors.
>
> If the iron chloride etch were better it wouldn't hurt to send those
> conclusions to the Smithsonian, British Museum, Weiner Naturhistorisches
> Museum, Max-Planck-Institut f?r Chemie (or whatever its called now)
> Collection, Paris Mus?um National d'Histoire Naturelle, etc. for comment.
> ;-)
>
> BTW, there are many variables not realated to the etch to consider.
> Though ferric chloride is 'easier', when it comes to mixing up, it doesn't
> mean it is less toxic in other ways. Ever wonder if it was legal or smart
> to pour spent solution down the drain or into the soils? Nickel chloride
> and nickel nitrate (produced in etching) are both mutagenic. Only Nickel
> chloride (a result of ferric chloride etching) is carcinogenic at levels
> 15 times lower than those produced from nitric acid etching. But with all
> the other heavy metal ions in iron meteorites, again, respect for the
> chemical is important regardless of what risks are perceived - it's never
> the full story and like smoking, everyone doesn't even have equal
> sensitivity.
>
> Kindest wishes
> Douh
>
>
> -----Original Message-----
> From: Jim Wooddell <nf114ec at npgcable.com>
> To: Meteorite-List <meteorite-list at meteoritecentral.com>
> Sent: Fri, Jan 27, 2012 6:48 am
> Subject: Re: [meteorite-list] Etching solution
>
>
> I believe there was an article by Hartman a few years back about the use
> of
> ferric chloride. The conclusion was that it gave a better etch??? I
> think
> it was in Meteorite-Times.
>
> Jim
>
>
>
> Jim Wooddell
> http://k7wfr
>
> ----- Original Message -----
> From: "MexicoDoug" <mexicodoug at aim.com>
> To: <mexicodoug at aim.com>; <markig at westnet.com>;
> <meteoritesnorth at hotmail.ca>; <meteorite-list at meteoritecentral.com>
> Sent: Friday, January 27, 2012 1:49 AM
> Subject: Re: [meteorite-list] Etching solution
>
>
>> "Besides water, I'm suspecting Nitric + acetone (Nitkeytone ?) and
> any
>> number of other solvents would work"
>>
>> OK, don'rt bother with this one! I just did; It actually etches, but
>> leaves a yucky finish. The fumes are no worse than other nitals,
> though I
>> wouldn't want to breath much of them until I knew more; but there
> didn't
>> seem to be any decomposition. I used reagent grade acetone to avoid
>> possibly nasty impurities, and the nitric acid concentration only
> 3.9%
>> just in case I hit a flash point, full face shield and a fan venting
> right
>> out the door. Nice to have had an 81 F day today and still its warm
>> enough to open the door ;-) nice etch, terrible residue.
>>
>> Kindest wishes
>> Doug
>>
>>
>>
>> -----Original Message-----
>> From: MexicoDoug <mexicodoug at aim.com>
>> To: markig <markig at westnet.com>; meteoritesnorth
>> <meteoritesnorth at hotmail.ca>; meteorite-list
>> <meteorite-list at meteoritecentral.com>
>> Sent: Fri, Jan 27, 2012 3:11 am
>> Subject: Re: [meteorite-list] Etching solution
>>
>>
>> "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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>>
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Received on Fri 27 Jan 2012 06:20:08 PM PST