Thanks for that MSDS Steve. So useful for the properties of ferric
chloride conveniently in your link.
One more thing to the discussion which IMO is constructive and useful
to anyone considering etching with some practical numbers but by no
means intended to be a manual sicne there are many variations that are
successful - the objective is simply to eat metal in a uniform and
contriolled manner ... But first a comment on the water in etchants:
Great all the info on these MSDSs...
for example, Steve's MSDS lists the composition of the Ferric Chloride
etchant:
9 % ferric chloride hexahydrate
91 % water
So this particular ferric chloride solution, quite a typical one, is
94.6% water!
It is low grade if you buy circuit board etchant complete with all the
unfiltered contaminants that are permissible and which can get into the
meteorite and contaminate it. It seems a bit much to me that so many
people worry about water getting in the meteorites with the nitric acid
procedure and for this reason demand pure alcohol, etc., and then some
other (or even the same) people etch with a solution that is 95% water
and don't think twice.
That is the reason I recommend a stock of 2 N to 3 N nitric acid which
is relatively mild and with, eg., a 50:50 dilution upon etching will
give something in the neighborhood of 6% on the low side if I remember
the math right just now, ignoring any (insignificant) density change.
If we go on the side of extra caution to avoid any potential criticism,
and have the patience and use the 2 N solution, a 50:50 w:w mix with
even pure ethanol might still result in around a nitric
acid:ethanol:water ratio of 6%:50%:44%. That's 44% water. If you used
50% ethanol (100 proof) you would be 69% water or so. Still well below
the 95% water used in FeCl3 etching.
On the other hand, even concentrated nitric acid mixed with pure 200
proof (100%) ethanol will yield a solution of a few percent water at
etching concentrations. I just don't see the benefit of worrying over
minimizing so much the water and making in favor of purehydroscopic
alcohol, since there is plenty of water around anyway. Perhaps someone
else has a good explanation, but I don't know it. No benefit that
three successive drying/alcohol bath cycles couldn't erase much better
anyway and when you consider the humidity in the atmosphere it all
becomes 'why bother?' for specimens that aren't hermetically sealed.
Then there is the suggestion of using dilute Nitric Acid alone, no
alcohol to deal with mixing and a 3 N stock solution is perfect to make
the range of concentrations you would want to etch. 3 N nitric is
probably something above 15% nitric acid, which means it is something
like 85% water. If you are used to this and have a procedure, you
could use this solution straight, however the best is probably a 50/50
dilution with water.
So the above are my recommendations spelled out. If anyone uses any
different concentrations with the straight acid it would be nice to
hear about. Solutions of 1.5 to 3.0 N nitric acid are much safer to
handle that muriatic acid and if it gets on you, a quick rinse is a
quick solution. The one major rule is to always wear eye protection.
I've had concentrate hydrochloric acid go into my eye from a splash as
a kid and there was no ill effect except on the nerves, but I suspect
Nitric acid is more risky in the eye. Visine eyedrops contain
hydrochloric acid I think, but nitric is another story if the burn scar
on my wrist from a lab accident is any indication, though that was
supercharged nitric acid, not the regular concentrated stuff in this
thread. The fuming nitric acid I made was in the 90% to 100% range,
bubbles like the movies mad scientist lab and is as scary as any
chemical possibly can be and it will eat flesh green upon contact.
Anyway, that gives somewhat a description of the dangers of
concentrated nitric acid and the relative mildness of the recommended
low concentrations. If you are extremely concerned you could drop it
down to 1 N, but I find that too slow for me unless I warm the
solution. There are a lot of trade offs going on behind the scenes. A
slow etch is usually more uniform, prettier, but there is more time for
something to go wrong, for some electrochemical reaction to discolor
the meteorite and for contaminants to enter the micro fissures,, get
around the inclusions, etc. That's why I'm on the higher side, and
that is also why FeCl3 is also so popular since it's usually formulated
for fast results. Plus at some point economy becomes important since
the difference in price between 1 N, 2 N and 3 N nitric acid prices is
not much and diluting these already pretty dilute acids is a piece of
cake vs. dealing with the concentrated stuff.
Hope that is helpful tio someone and if you have experience with
different temperatures / concentrations / ratios please post! If there
are any errors be kind to correct them as it is late ;-)
Kindest wisdhes
Doug
-----Original Message-----
From: Steve Dunklee <[email protected]>
To: markig <[email protected]>; Meteorite-list
<[email protected]>; MexicoDoug <[email protected]>
Sent: Fri, Jan 27, 2012 11:37 pm
Subject: Re: [meteorite-list] Etching solution msds ferric chloride
http://www.sciencelab.com/msds.php?msdsId=9925886
also may cause laurancite disease in irons or uncontrolled rusting
cheers
steve
--- On Sat, 1/28/12, Steve Dunklee <[email protected]> wrote:
From: Steve Dunklee <[email protected]>
Subject: Re: [meteorite-list] Etching solution
To: [email protected], [email protected],
"MexicoDoug"
<[email protected]>
Date: Saturday, January 28, 2012, 2:59 AM
http://multietch.com/
cheers
--- On Sat, 1/28/12, Steve Dunklee <[email protected]>
wrote:
> From: Steve Dunklee <[email protected]>
> Subject: Re: [meteorite-list] Etching solution
> To: [email protected],
[email protected],
"MexicoDoug" <[email protected]>
> Date: Saturday, January 28, 2012, 2:52 AM
> hi! cheers!
> Steve Dunklee
> http://www.sciencelab.com/msds.php?msdsId=9925886
>
>
>
>
>
>
>
>
> --- On Sat, 1/28/12, MexicoDoug <[email protected]>
> wrote:
>
> > From: MexicoDoug <[email protected]>
> > Subject: Re: [meteorite-list] Etching solution
> > To: [email protected],
> [email protected]
> > Date: Saturday, January 28, 2012, 12:46 AM
> > 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 <[email protected]>
> > To: nf114ec <[email protected]>;
> > meteorite-list <[email protected]>;
> > MexicoDoug <[email protected]>
> > 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" <[email protected]>
> > To: <[email protected]>;
> > <[email protected]>
> > 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 für Chemie (or
> whatever
> > its called now)
> > > Collection, Paris Muséum 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 <[email protected]>
> > > To: Meteorite-List <[email protected]>
> > > 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" <[email protected]>
> > > To: <[email protected]>;
> > <[email protected]>;
> > > <[email protected]>;
> > <[email protected]>
> > > 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 <[email protected]>
> > >> To: markig <[email protected]>;
> > meteoritesnorth
> > >> <[email protected]>;
> > meteorite-list
> > >> <[email protected]>
> > >> 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 <[email protected]>
> > >> To: MexicoDoug <[email protected]>;
> > meteoritesnorth
> > >> <[email protected]>;
> > meteorite-list
> > >> <[email protected]>
> > >> 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" <[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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> > >>>>
> > >>>>
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> > >>>
> > >>>
> ______________________________________________
> > >>>
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