From: DENNIS KLINKER (dennis@klink47.freeserve.co.uk)
Date: 02/20/03-10:13:25 AM Z
Gordon this is a good idea,i am sure with all the expertise on this list it
will not be a problem,can i bring to your attention the book "Overexposure"
Health Hazards in Photography by Susan Shaw and Monona Rossol published by
Alworth Press ISBN 0-9607118-6-4 although i could not see any mention of
Aqua Regia there is a chapter on Photo Alt.
Dennis Klinker
----- Original Message -----
From: "Gordon J. Holtslander" <holtsg@duke.usask.ca>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Thursday, February 20, 2003 3:29 PM
Subject: Aqua Regia & safey
> I received a lot of private email concerning Dick Sullivan's recent
> posting entitled "Kitchen brewed gold chloride! Not!" (Feb 10 2003)
> about the safety of working with Aqua Regia. A copy of his posting is at
> the end of this message.
>
> This stems from an article entitled "Make your own Gold Trichloride"
> written by Liam Lawless, published in the World Journal of Post-factory
> Photography in May 1999 (page 30). In this article Liam Lawless
> summarizes a method in which gold trichloride is produced from "scrap
> gold".
>
> As others have noted Liam did not suggest doing this procedure in the
> kitchen or darkroom. His procedure also avoids the problems associated
> with storing Aqua regia by neutralizing the aqua regia solution at the end
> of the procedure.
>
> I considered how other publications associated with alternative
> photographic processes dealt with issue of working with hazardous
> chemicals.
>
> I did a "review" of many of the alt-photo web sites, those written as a
> public service and commercial web sites, as well as a number of books.
> Almost all of these give some sort of warning that many of the
> chemicals used are hazardous and that people should assume everything is
> hazardous unless they know otherwise.
>
> None of the sites I visisted provided any specific information on how to
> deal with the potential hazards. Most sites didn't even identify which
> materials were hazardous and which were not.
>
> Liam's article, like most other alt-photo information currently available
> assumes the worker is aware of the hazards involved.
>
> On the alt-photo list its assumed that everyone knows how to handle the
> potentially dangerous chemicals. When we post a message about salted
> paper we don't describe the hazards and necessary precautions to be taken
> when working with silver nitrate. The same for dichromates in gum
> printing and so on.
>
> A lot of the people working in this field come into it with some sort of
> training that informs them of the appropriate laboratory/chemical
> practices. As alt-photo becomes more popular, this is becoming less and
> less common.
>
> The lay-person starting to work with alt-photo can usually find plenty of
> information about the hazards, but little information on how to work
> safely in this field.
>
> What I would like to see is an effort to properly document the potential
> risks of each process, the basics of the chemistry involved (why there is
> a safety risk) and the appropriate steps that should be taken to minimize
> the risks.
>
> If people are genuinely concerned about providing indepth safety
> information, perhaps list members could collaborate on producing
> documentation on the proper safe darkroom/lab practices for each process.
> I would be happy to post these on the alt-photo archive site.
>
> Since the use of Aqua Regia is such a concern, perhaps we could start with
> this process. At this point anyone going through the archive looking for
> information on aqua regia and gold chloride will get the left with the
> impression that some people think its dangerous and some people think its
> not.
>
> I would like to ask the people who have worked with aqua regia and gold
> chloride to collaborate on a document that clearly outlines the hazards,
> and the appropriate precautions. If people are unable to agree I would
> like to get dissenting opionions, and post these.
>
> I will post one or more documents on the alt-photo archive site.
>
> If people are unwilling to do this then I would insist that the issue of
> Aqua Regia safety should no longer be discussed on this list.
>
> Thanks
>
> Gord Holtslander
> List Manager
>
> On Mon, 10 Feb 2003, Richard Sullivan wrote:
>
> > Subject: Kitchen brewed gold chloride! Not!
>
> >
> > Several years ago there was a brouhaha here over an article in Post
Factory
> > No 3 on making gold chloride in your kitchen or darkroom.
> >
> > The issue at hand was safety. I believe some correction were made in No
4
> > but the problem still exists as many here might read No. 3 without the
> > benefit of the corrections in No 4. It is highly doubtful that anyone
would
> > try this trick at home but someone just might as the article proposes
just
> > such a project.
> >
> > Several had said here that aqua regia would not explode in closed
> > containers. Wrong!
> >
> > Liam Lawless, author of the article, said the following June of 1999 on
the
> > list via another members repost or forward.
> >
> > Liam says:
> >
> > >We have perhaps been remiss in implying that this process can be
carried
> > > >out indoors, which it definitely should not without the proper
equipment,
> > > >etc., but the only other point that gives me real cause for concern
is your
> > > >assertion that stored aqua regia could explode.
> >
> > Not only my assertion but that of the American Industrial Hygene
Association!
> >
> > >I have, therefore, spoken
> > > >to a chemist about this today (whose name I shall not give as he has
> > > >nothing to do with this debate, but who has some interesting views on
> > > >safety and responsibility that I hope he will one day share), and the
gist
> > > >of what he told me is as follows.
> > > >
> > >Aqua regia is a stable mixture of acids that will not spontaneously
explode
> > > >at normal temperatures, though a small amount of pressure will build
up in
> > > >its container until any air present is saturated with the acid
vapours. It
> > > >should, of course be kept in a glass or plastic container with screw
cap,
> > > >which is capable of withstanding the small build-up of pressure that
> > > >occurs. And the general rule for acids is that they should be stored
in a
> > > >cool, dark place; heat increases the pressure, and light may cause
> > > >photolysis that in turn causes decomposition and the liberation of
gases.
> > > >It is also important that the container is clean, to avoid
contaminants
> > > >that could catalyse decomposition.
> >
> > This is patently wrong and compounds the error in PF No 3.
> >
> > To add to the warnings I have found the following at:
> >
> > http://www2.umdnj.edu/eohssweb/aiha/accidents/explosion.htm#Two
> >
> > Do a page search on "aqua regia" as the pertinent part is about 80% down
> > the page. It is from the American Industrial Hygene Association on the
New
> > Jersey Medical and Dental College site. It highlights two cases of aqua
> > regia explosions. These were not just caps blowing off but violent
> > explosions shattering the glass bottles with enough force to break other
> > nearby bottles. Had someone been in the room and been the subject of
flying
> > glass and hot aqua regia spray it could have been very messy.
> >
> > The text follows:
> >
> > >Two Explosions Involving Aqua Regia (top)
> > >Key Learning Points
> > >1. Use a reagent that is milder than aqua regia for cleaning glassware
if
> > >it will suffice.
> >
> >
> >
> > >2. Do not take aqua regia out of the fume hood in which it was
prepared,
> > >and do not store it there either; make only what you need and destroy
the
> > >residue. Aqua regia can be destroyed by cautious and careful dilution
with
> > >water - talk to your supervisor or your safety office for a detailed
> > >procedure. If necessary, the solution can then be neutralized and
disposed
> > >of in the approved manner.
> >
> >
> >
> > >3. Never put aqua regia in a closed container or near flammables.
> >
> >
> >
> > >There have been explosions involving aqua regia ( a mixture of
> > >hydrochloric acid and nitric acid) reported at two universities. Both
of
> > >the incidents took place in chemistry laboratories.
> >
> >
> >
> > >In the first incident, a graduate student was using aqua regia for the
> > >cleaning of NMR tubes. When he was finished, he placed the residues
(about
> > >50-60 ml) in a 4 litre waste bottle, capped it tightly and placed it in
a
> > >flammable storage cabinet. Approximately one hour after the bottle was
> > >placed in the cabinet, it burst, breaking an adjacent bottle of
pyridine.
> > >Luckily, the pyridine did not ignite and other nearby bottles
containing
> > >flammable solvents did not become involved. The pyridine leaked onto
the
> > >floor, where it dissolved floor tiles and created a lingering bad
smell.
> > >The second incident occurred in a fume hood in a synthetic chemistry
> > >laboratory. A tightly closed waste bottle containing used aqua regia
> > >exploded, most probably due to pressure buildup inside the bottle.
> > >Since the sash was not completely closed the broken waste bottle was
not
> > >contained. Broken glass as well as some liquid acid waste were thrown
out
> > >of the hood. Since nobody was near the hood at that moment, there were
no
> > >injuries. Moreover, a nearby bottle of mercury nitrate waste was also
> > >broken as well as the secondary container, so that a small spill (less
> > >than 1 liter) of liquid acid and solid mercury nitrate occurred inside
the
> > >hood.
> >
> >
> >
> > >What is aqua regia?
> > >Aqua regia has been used by chemists for centuries, especially as a
medium
> > >for dissolving noble metals but also for other purposes. It is a
mixture
> > >of concentrated hydrochloric and nitric acid which forms a powerful
> > >oxidizing medium. Mixing an oxidizer with organic materials may result
in
> > >a highly exothermic reaction. Even without other materials present, a
> > >chemical reaction occurs slowly and brown fumes of NO2 can be observed
(in
> > >freshman chemistry terms, nitric acid is reduced and hydrochloric acid
is
> > >oxidized). The activity as a dissolving agent decreases slowly and so,
by
> > >definition, the solution is unstable - it should be used "freshly
prepared".
> >
> >
> >
> > >Rules for using aqua regia
> > >Aqua regia is often used as a substitute for chromic sulfuric acid
> > >cleaning solutions. However, aqua regia is also corrosive and strongly
> > >oxidizing. It is essential for some purposes but should not be used for
> > >routine cleaning of glassware. If a milder reagent will suffice avoid
> > >using aqua regia. Alternatives include ultrasonic baths, alconox or
> > >similar detergents, Pierce RBS-35 (available from VWR) or similar
> > >detergents or biodegradable surfactants.
> >
> >
> >
> > >Be aware that sufficient pressure can build up in a short amount of
time
> > >to burst the container, even from a very small volume of aqua regia.
> >
> >
> >
> > >If it is decided that aqua regia is needed, wear protective clothing
> > >(goggles, gloves, coat) and work in a clean well-ventilated fume hood.
> > >Keep the sash down when reactions are in progress.
> >
> >
> >
> > >Never take aqua regia out of the hood.
> >
> >
> >
> > >Prepare it, use it, and destroy any excess in the hood in which it was
> > >prepared.
> >
> >
> >
> > >
> > >Only prepare the amount of aqua regia you need for immediate use. Never
> > >store it and never put it in a closed vessel, since evolved gases will
> > >cause a pressure build-up and possible explosion.
> >
> >
> >
> > >Aqua regia is a strong oxidizer. It is incompatible with organic
solvents,
> > >flammables and any reducing agents.
> >
> > --Dick Sullivan
> >
> >
> >
>
> ---------------------------------------------------------
> Gordon J. Holtslander Dept. of Biology
> holtsg@duke.usask.ca 112 Science Place
> http://duke.usask.ca/~holtsg University of Saskatchewan
> Tel (306) 966-4433 Saskatoon, Saskatchewan
> Fax (306) 966-4461 Canada S7N 5E2
> ---------------------------------------------------------
>
>
>
>
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