Mercuric Chloride

[Vlad Soare]

Hello,

What precautions should be taken when handling mercury(II) chloride?
Besides the obvious things, like wearing gloves, not eating/sniffing/drinking the stuff, keeping it away from children, etc., is there anything else I should be especially careful about?

Thank you.

 

[Necator]

MSDS can be found here. Personally, I would not even consider getting near it outside a well controlled chem lab, with good guidance from experienced lab personnel.

 

[Tony-S]

I'd also stay clear of it. It's really bad stuff and has an LD50 that's pretty low. Unless you have a fume hood, proper laboratory attire, and the appropriate training for safely handling it, it's not something to screw around with.

 

[brianmquinn]

I work in a Chemical lab. I went out of my way to find an alternate method when the procedure we were doing called for HgCl2. It is a Cumulative poison like Pb. Avoid it's use if possible.

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.

 

[john_s]

You also need to consider disposal after use. In most places you are obliged to use an approved agency. It would be appallingly irresponsible to to otherwise.

 

[Adrian Twiss]

I got some Mercuric Chloride in a batch of Chemicals I inherited from a retired photographer. As I had no use for it I thought I would have trouble disposing of it. Luckily my next door neighbour was an analytical chemist so he was able to dispose of it for me in the approved manner.

 

[alanrockwood]

Another vote from me to avoid using the mercury compound if at all possible.

Here is a true story about working with mercury compounds, not mercury (II) chloride, but close enough to on-topic to be interesting I hope. A few years ago there as a professor (Karen E. Wetterhahn at Dartmouth College) who specialized in the chemistry of mercury compounds. She was an experienced researcher. (Notice the use of the past tense.) She spilled a small amount of a certain organo-mercury compound on her gloved hand. It turned out that the this compound was able to diffuse through the latex glove as well as through her skin.

Here is a wikipedia giving a short history of what happened next: "The accidental spill occurred on August 14, 1996 but symptoms of her mercury poisoning were not detected until six months later, at which time the poisoning was irreversible. Wetterhahn suddenly became very ill in January of 1997 and was hospitalized; she then went into a coma which lasted until she died in June."

 

[Ken Nadvornick]

Re: Karen E. Wetterhahn, see "Dead Link Removed" by Karen Endicott, Dartmouth Alumni Magazine, 1998.

Ken

 

[Jerevan]

Sad but interesting article, Ken. Well worth a read for all of us, even when it comes to the handling of "normal" darkroom chemicals.

 

[dfoo]

Given that Mercuric Chloride was used as a treatment for syphilis it seems doubtful it is as toxic as the unfortunate Karen Wetterhahn story would have us believe.

 

[brianmquinn]

Given that Mercuric Chloride was used as a treatment for syphilis it seems doubtful it is as toxic as the unfortunate Karen Wetterhahn story would have us believe.

Remember the old saying about the cure being worse than the disease?
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.

 

[dfoo]

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!

 

[Ken Nadvornick]

Sad but interesting article, Ken. Well worth a read for all of us, even when it comes to the handling of "normal" darkroom chemicals.

Yes, I thought so too.

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.

Ken

 

[Maris]

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.

 

[alanrockwood]

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.

 

[Vlad Soare]

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.

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.

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.
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?

 

[brianmquinn]

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.

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.

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.

 

[holmburgers]

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.

my 2¢

 

[brianmquinn]

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?

 

[holmburgers]

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...

 

[brianmquinn]

Here is a quote from The darkroom cookbook
By Stephen G. Anchell
It is an excellent and modern book and I think everyone who does B&W work should read it.
Not for safety reasons but so you can play better in the darkroom.
It’s lots of fun to try out the formulas in this book.

 

[holmburgers]

Perfect! Now I really don't want to use it.

 

[brianmquinn]

Safety advice is not what will cripple or kill someone, it is the lack
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...

Here is my objective information. You are young and most likely have not seen any of your friends DIE as a result of poor decisions. I have. I did a LOT of STUPID things in my youth. I hope my children, who I love very much, will not try any of the foolish things I did when I was younger.

 

[Kirk Keyes]

Learning how to handle chemicals is probably something you really don't want to learn over the interweb. Years of college chemistry labs and workplace training are really the way to lean this stuff. And even then, there are some things where there is a general lack of real info, like the dimethylmercury example above.

I would not recommend using mercury compounds in the home or commercial photo lab these days. They are not what we consider "safe" for general use these days. There are safer ways to achieve similar results nowadays.

That said, I used mercury intensifiers my self as a teenager 30 years ago.

 

[holmburgers]

Here is my objective information. You are young and most likely have not seen any of your friends DIE as a result of poor decisions. I have. I did a LOT of STUPID things in my youth. I hope my children, who I love very much, will not try any of the foolish things I did when I was younger.

Look, I don't even want to use mercuric chloride or any mercury compound for that matter, but if you look through the thread, very few actual FACTS were given. That's all I'm getting at!

Excuse me now, it's the time of day that I usually play with broken thermometers....