[meteorite-list] Etching solution

From: MexicoDoug <mexicodoug_at_meteoritecentral.com>
Date: Fri, 27 Jan 2012 19:46:35 -0500 (EST)
Message-ID: <8CEAB6D6B98C920-1584-8ED6_at_webmail-m151.sysops.aol.com>

Hi Mark,

"Would appreciate a reference for the nickel chloride being 15 times
more carcinogenic than soluble nickel nitrate."

That's not what I wrote although it could be true I have no such
reference to support the above.

What I did write was:

"Only Nickel chloride (a result of ferric chloride etching) is
carcinogenic at levels
15 times lower than those produced from nitric acid etching."

There is a huge difference between what you understood and what I
actually wrote as threshhold toxicity levels don't necessarily equate
to activity factors. This is because the body has dozens of competing
homeostatic (metabolic, immune/allergic, etc.) processes that relate to
detoxification and an imbalance occurs when that one single straw to
many put on the camel breaks its back.

The reference should be any MSDS (Material Safety Data Sheet), just
check whichever one you have access to or dig up first.

Toxicology, especially when it comes to carcinogens is so complex that
I don't think anyone understands it, or they would already gotten a
billion buck grant from the NIH by now. It just comes in many small
pieces. I share your opinion that we should reference and I'm sorry if
I just dumped all this information for discussion, but it was more
useful that keeping i to myself. I've not found a reasonable layman's
treatise anywhere on the subject so I figured the met list was as good
as it gets without opening yet another research project to compete with
the other ones I've got floundering.

Anyway, the exposure limits I mention I believe are for lab rats
approximating other mammals, like humans. Again, the more you get into
this the more it's hard to muzzle oneself becasue now we're getting
further into it:

so - must ask, can you breath it in (probably not in most cases, but
definiely cover your mouth, eyes, and any other open oriface such as a
wound when doing this. That should be 'common knowledge' but really if
doing it for the first time, maybe not.

and - must ask, so how permeable is the skin to it ... becasue if one
has a 15X lower threshhold but is 15x more difficult to uptake, then
we'd have a wash. Then there are solubility issues, but these both
look like they are well soluble, just a glance at the MSDS will answer
that.

last here, but definitely not any closure, is; what's the significance
of getting these things into ones local envoironment and the general
environment (waters, soils, air, etc.). We don't think about this but
doing it out on the concrete patio outside of the kitchen and tossing
the waste into the immediate area, it will dry and become particulate
contaminants which over time the wind will distribute in the lungs of
little boys playing there, through the kitchen window, etc. Probably
no big deal in most cases, but there is always that one case that
something goes terribly wrong. And getting back to the maximum
'permissible' exposure limit (sheesh, now to add residence time,
cumulative properties in the body, it's head spinning).

Which is why, in this case for a rat which is assumed to react as a
human (but may not), at least we can point a finger at the threshold of
toxicity, which itself is a a single point determined after half of the
subjects have croaked, illustrating that half are just fine whereas it
is toxic to half of them at even lower levels, or something along tose
lines.

As for your other reference of isopropyl vs. ethyl alcohols and
explosion hazards, I'm sorry but perhaps someone else has more time to
develop this properly vs. this informal discussion forum. If I had
time and a full lab, I would start by maing a ternary diagram of the
two alcohols and nitric acid, and plot the flash point of the mixture
for starters. The information I saw was anecdotal and not rigorous nor
very quantitative. However I don't hacve time to spend on this subject
any more due to personal circumstances and recommend that you try
googling. This is not a case of a proving beyond a reasonable doubt
that it is more explosive. However there are enough warnings out there
thaty would seem to suggest more violent and higher incidence of
isopropanol-HNO3 mixtures than the EtOH analog, since we are talking
about personal safety. Clearly Isopropyl alcohol is similar
inproperties relating to etching that given the more widespread use in
general metallurgy of EtOH, it's the devil we know better

I'm convinced of the Isopropanol/ethanol issue all I need to be more
vigilant. But that doesn't mean I wouldn't use it if there was some
reason to do that. Rather than obsessing too much over a terribly
complex issue and coming to the same inconclusion, I'd just make
simple, yet effective modifications to my procedure -
Why deal with comncentrated nitric in a home environment at all? How
silly! You (general) want to save a few pennies at your own risk,
pennywise --- just have the Hazardous Materials emergency number handy.
  Otherwise buy the diluted acid= problem significantly minimized. You
want to make etchant? Don't make such a large amount in a
bottle/beaker at once. Don't use such an excess when etching,
experiment by painting it on with a brush instead - problem
significantly minimuzed ... and so on.

Hope this gives better insight. Having THE answer to these things is
too tall an order, yet experience and common sense are why other
individuals can etch more easily than making scrambled eggs. Our
appreciation of risk is terribly distorted. Once I was in a discussion
with Sterling sopmewhere discussing this and he even referenced
someplace, proabbly wiki the bias I described had a name. You know,
the same one that evaluates whether to be frightened from falling
asteroids vs. driving to work in the morning. I'm still waiting for
the thriller movie, "Highway jaunt" where no rogue asteroids or
murderous psychopats pass by, but Strawberry Shortcake girl just takes
her car for a spin and suddenly every individual in the traffic stream
has a compulsion to run over her on her sweet bicycle. Point of the
dumb example being the high risk we have experience has much lower fear
factor than the almost non-existent risk which ends in carnage and
mahem, even if a decision tree analysis shows that the friendly risk is
a million times more likely.

Kindest wsihes
Doug

PS I have stretched too much to participate in this give some other
difficult responsibilities I ahve at the m,oment so I did my best and
will likely retire for a while to catch up on things.

PPS, After all this, I think my new etchant of choice will be Coca
Cola. No doubt it works or can be tweaked to, too.



-----Original Message-----
From: Mark Grossman <markig at westnet.com>
To: nf114ec <nf114ec at npgcable.com>; meteorite-list
<meteorite-list at meteoritecentral.com>; MexicoDoug <mexicodoug at aim.com>
Sent: Fri, Jan 27, 2012 6:20 pm
Subject: Re: [meteorite-list] Etching solution


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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Received on Fri 27 Jan 2012 07:46:35 PM PST