[meteorite-list] Etching solution

From: Richard Montgomery <rickmont_at_meteoritecentral.com>
Date: Fri, 27 Jan 2012 18:38:55 -0800
Message-ID: <809ABA2680464D658DF6A58D11CD7A48_at_bosoheadPC>

Jim...nice post. Can you elaborate on the compound?


----- Original Message -----
From: "Jim Wooddell" <nf114ec at npgcable.com>
To: "Mark Grossman" <markig at westnet.com>;
<Meteorite-list at meteoritecentral.com>; "MexicoDoug" <mexicodoug at aim.com>
Sent: Friday, January 27, 2012 6:29 PM
Subject: Re: [meteorite-list] Etching solution


> Hi Mark and Doug and all!
>
> Another good topic...that goes along with etching meteorites is the
> polishing compounds used prior to etching. For example, a 1 micron
> polishing compound or mixture has it's own set of safety issues. The
> concern is absorption through the skin, etc! Most probably do not polish
> to
> that level???? But some do!
>
> Jim
>
>
>
> Jim Wooddell
> http://k7wfr.us
>
> ----- Original Message -----
> From: "Mark Grossman" <markig at westnet.com>
> To: <Meteorite-list at meteoritecentral.com>; "MexicoDoug"
> <mexicodoug at aim.com>
> Sent: Friday, January 27, 2012 6:17 PM
> Subject: Re: [meteorite-list] Etching solution
>
>
>> Hi Doug,
>>
>> Thanks for the comments.
>>
>> I'm a Certified Industrial Hygienist and a Certified Safety Professional
>> and have been in the chemical health and safety field for more years than
>> I care to admit. Before that, I used to work as an analytical chemist.
>>
>> There is a lot of information you have passed on to the list with good
>> intent, but there are several assumptions that you are making that are
>> not substantiated. However, I agree that the purpose of the list is not
>> to get into a deep discussion of health and safety issues. Anyone who
>> would like to do so can contact me off-list.
>>
>> But I do have a concern that many of the comments in the threads have
>> been a bit too casual - that may be my interpretation or reading only -
>> and if so I apologize. But we have identified three unfortunate
>> experiences with nitric acid/ethanol since the discussion started - and I
>> want to do my best to warn those of the potential hazards that are
>> involved before someone gets hurt or has another unfortunate tale to post
>> on the internet. I think we all have the same objective as far as that
>> goes.
>>
>> One last item - you may want to calculate the percent composition of the
>> 3 molar (normal) solution you are recommending and compare the figure to
>> Bretherick's data for instability.
>>
>> Mark
>>
>> Mark Grossman
>> Meteorite Manuscripts
>>
>>
>> ----- Original Message -----
>> From: "MexicoDoug" <mexicodoug at aim.com>
>> To: <markig at westnet.com>; <Meteorite-list at meteoritecentral.com>
>> Sent: Friday, January 27, 2012 7:46 PM
>> Subject: Re: [meteorite-list] Etching solution
>>
>>
>> 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
>>>>>> ______________________________________________
>>>>>>
>>>>>> Visit the Archives at
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>>>>>>
>>>>>> ______________________________________________
>>>>>>
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>>>>>
>>>>> ______________________________________________
>>>>>
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>>>>
>>>>
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>>>>
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>
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Received on Fri 27 Jan 2012 09:38:55 PM PST