Remember the old saying about the cure being worse than the disease?
Originally Posted by dfoo
It was only used a desperate treatment for a disease that literally eats holes in your brain.
The primary danger with Mercury Compounds is their toxicity to the Central Nervous System (CNS). These organs contain a large amount of lipid. Different Mercury compounds differ in toxicity mainly due to their lipid solubility. Methyl Mercury is much more lipid soluble then mercuric chloride or elemental liquid mercury metal. Methyl Mercury will go to the CNS and stay there to kill the cells. But it is possible for other forms of Mercury to be converted to the methyl form in your body.
I'm not saying that its not poisonous, I'm saying comparing it to something that will kill in six months from two small drops on a latex glove seems a little over the top. Unless I'm wrong, in which case I guess I'll hear all about it!
Yes, I thought so too.
Originally Posted by Jerevan
I posted the link as a historical reference only, given that Ms. Wetterhahn's name and her ordeal had been mentioned previously. It was not intended to make a case for any sort of implied equivilency with the use of normal photographic darkroom chemistry. It's just an overall cautionary tale that, as you say, is well worth a read.
"When making a portrait, my approach is quite the same as when I am portraying a rock. I do not wish to impose my personality upon the sitter, but, keeping myself open to receive reactions from his own special ego, record this with nothing added: except of course when I am working professionally, when money enters in,—then for a price, I become a liar..."
— Edward Weston, Daybooks, Vol. II, February 2, 1932
Decades ago when I was an analytical chemist with a specialisation in poisons the dangers of mercury were well known. But mercury was widely used; for metal amalgamation, for electrochemistry electrodes, for preserving organic solutions, and so on. Mercuric chloride is an intense poison like potassium cyanide but it can be safely handled given normal laboratory discipline.
Imagine my surprise one day when the laboratory staff, me included, were tested for mercury load and significant quantities were found. What happened? Amazingly it was broken thermometers that nearly did us in.
A smashed mercury thermometer bulb releases thousands of minute globules that seek out gaps and cracks in floors and benches. A single busted thermometer in an average size darkroom delivers a mercury vapour load at least ten times the legal industrial limit and it will keep delivering for months. The body hides this mercury in fatty tissue where it does no harm until saturation happens. Then even a sub-acute dose can kick you over the edge; poor Karen Wetterhahn.
If you are working in a darkroom in which a mercury thermometer has been broken and the mess hasn't been cleaned up with a passivating agent like potassium sulphide do something about it.
Photography, the word itself, invented and defined by its author Sir John.F.W.Herschel, 14 March 1839 at the Royal Society, Somerset House, London. Quote "...Photography or the application of the Chemical rays of light to the purpose of pictorial representation,..". unquote.
We (myself included) have almost universally recommended not using mercury (II) chloride, and I think it is good advice. Now I think it we should address the original poster's original question, which is to receive suggestions on how to safely handle the material.
I don't think I have anything to suggest at this time on that topic.
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Thank you all for your replies.
While all mercury compounds are poisonous, each of them is poisonous in its own way, and I'm sure that not all of them can kill you with one drop, and not all of them can pass through gloves.
Back when I was a kid, friends of mine used to play with mercury droplets spilled from broken thermometers. They didn't die. So I'm not scared by mercury itself, though I know that certain compounds are indeed extremely bad, like the dymethilmercury that killed Karen Wetterhahn.
I started this thread to find out whether mercury(II) chloride was closer to dymethylmercury (that is, don't look at it, don't come near it, don't even think about it), or rather closer to potassium cyanide (that is, very dangerous in the wrong hands, but reasonably safe if you take basic precautions and don't do anything stupid). I tend to believe it's the latter, given that it has been used in photography for a long time, and no casualties among photographers seem to have been noted.
That's true, Brian, but then so is potassium cyanide. Yet people are able to use it for wet plates, and I have yet to hear of a photographer who died of cyanide poisoning.
It is a health hazard 4. The most dangerious and defined as:
Very short exposure could cause death or serious residual injury even though prompt medical attention was given.
Hydrogen sulfide is also a 4, but I have yet to hear of a photographer who died because he used a sepia toner that released hydrogen sulfide.
What I'm trying to say is that health hazard classification is just a rough approximation. Its being a 4 doesn't tell me anything I didn't already know, namely that it's very dangerous once it gets inside one's body.
OK, so it's nasty, it's poisonous, it's a bogeyman, it's best avoided. But can it nevertheless be handled safely in a home darkroom?
From the MSDS I infer that it can. It seems to indicate that gloves, goggles and good ventilation are the only requirements.
Are the solutions as nasty as the dry compound? I mean, after I dissolve the mercuric chloride in water to make a negative intensifier, will the tray release poisonous fumes?
Last edited by Vlad Soare; 01-13-2011 at 01:46 AM. Click to view previous post history.
I work with CN all the time and it does not scare me. Hg does. The reason for that is a sub lethal dose of CN will clear out of you body in a short while and there will be no lasting effects. Hg goes in and stays in. As I said before it is a cumulative poison that gets most people over time rather than all at once. This is why it took decades for people to be aware it is such a bad thing it should be avoided if possible.
Originally Posted by Vlad Soare
Also as far as the protective gear you listed just look up an MSDA sheet for Sodium Chloride. It will list the same requirements.
As I said before I will not use it and found a alternate method when my work required it. My new method works fine and I will do not have to worry about ill effects that may not show up until after years of working with it.
I think it's clear that this is a dangerous chemical, but by not answering the OP's questions specifically, we're not teaching anyone how to handle it safely.
A realistic account of the dangers is probably going to be more effective than the ole' "don't even think about it!" technique. It doesn't work with kids, it doesn't work with adults.
The reason why no one is telling HOW to work with it is because we feel there is NO WAY to do so in an average darkroom. If I give advice on how to use it and after 5 years of following my advice the signs of mercury poisoning start to show what am I do? Say sorry, I gave you poor advice and crippled or killed you?
Safety advice is not what will cripple or kill someone, it is the lack thereof which will do that. I'm just making the point that no one has given any safety advice yet, and what if some cavalier experimenter decides to do it besides everyone's warnings? Well they certainly won't know how to do it safely. It the proper safety advice is given, perhaps it will become self evident that one shouldn't be dealing with such compounds in their darkroom.
I'm just trying to point out that everyone comes forth with their opinions and subjective advice, yet not much objective information. Chock it up to being an advocate for the devil I guess...