| Platinum Green
The personal and environmental hazards of platinum printing.
The first question posed by many people
concerning platinum printing is: "Is it poisonous?" The
answer is yes, but that really isn’t telling you very much
since the word "poisonous" is quite vague. At best it
just says that if it is mishandled, something bad will happen.
Things can be poisonous in a number of
ways. One way is that it can cause immediate or short-term harm.
For instance, ingest enough of a cyanide compound and you will quickly
get very sick and probably die. Things can be poisonous in a cumulative
manner such as lead or mercury building up over a period of time
causing gradual debilitation, sickness and possibly death. Two examples
of this are the "Mad Hatters" in Alice and Wonderland.
Mad because hat makers were gradually poisoned by the mercury they
used in the felt making process and it caused them to act crazy.
Most photographers are probably familiar with Gene Smith’s
picture from his Minamata series of the Japanese women holding the
young child in the bath. The child was malformed and sick from eating
fish contaminated by mercury from a local factory.
The poisonous nature of platinum printing
for the most part is of the immediate kind, that is if you’re
alive and well the next morning, you probably don’t have anything
to worry about.
The use of a good mask and gloves will
provide most of the protection you’ll need. The mask should
be of the high quality triple layer paper variety and should have
two straps to hold it on, one to go on the crown of the head and
the other the nape of the neck. 3M makes good ones and are generally
available at paint and hardware stores. In my opinion, the rubber
respirator types are very uncomfortable and are overkill for platinum
printing. Decent plastic or rubber surgical type gloves are now
also readily available and are sufficient for all your needs. Buy
a quantity so that you change them often and not risk getting holes
in them. Club type discount stores usually sell the plastic variety
in boxes of 100 or more for under ten dollars.
Beyond the use of a mask and gloves you
should follow good common sense rules:
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Label
bottles and containers. |
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Store
your chemicals out of reach of children and never in your food
refrigerator. You might not have kids but your friends do. |
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Don’t
eat in your printing area. One of our printers pointed out that
ferric oxalate solution looks just like the Glenfiddich Scotch
he was fond of drinking while he printed. |
It must be noted that in all cases,
you must be apprised of all local regulations and adhere to them
as they have precedence.
Specific chemicals used in platinum
and palladium printing
The following is a list of the compounds used in normal platinum
and palladium printing and my opinion
of the hazards that they pose to personal health and to the environment.
Platinum and palladium salts
These salts are poisonous in their normally used concentration for
platinum printing, it would probably take 8 or 10 grams to kill
a adult. Unlike the cyanides (which are not used normally in platinum
and palladium printing) which take less than a gram to kill an adult,
this 8 to 10 gram quantity is quite a bit and it would be difficult
to ingest this much accidentally.
These salts pose very little danger to the environment for several
reasons:
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They
are not "heavy metals." Yes they are metals, and yes
they are heavy, but the term "heavy metal" as used
to refer to metals such as arsenic, cadmium, selenium, lead,
and mercury. These metals as insidious, nasty, poisonous and
can accumulate and build up in your body over a long period
of time. |
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They are
what are called "noble" metals and as such they are
almost always found in nature in their pure metallic state,
thus the reason they are called noble metals. The reason they
are found in their pure state is that when they make salts with
other chemicals, they don’t bond too tightly. The weak
bond is quickly broken when these salts go into the natural
environment and what happens is that the salt breaks down into
platinum or palladium metal and the chlorine salts. In the case
of palladium it is palladium and sodium chloride (table salt)
and in the case of platinum it is potassium chloride and platinum.
The potassium chloride is commonly used as a salt substitute
for low sodium dieters. The platinum and palladium metal can
be ingested and will pass through the body without harm. |
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They are
very expensive which means there is a financial incentive not
to go around willy nilly spreading them about the environment. |
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They are
used in very small quantities. |
Developers
Platinum and palladium developers are almost always salts of the
weak organic acids. Weak organic acids are found commonly in the
foods we eat.
These include:
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Citric
Lemons etc. The sour taste |
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Oxalic
Green leafy vegetables like spinach and other greens –
the bitter taste |
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Malic
Apples – the tart taste. |
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Tartaric
Wine – the sour taste |
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Acetic
Vinegar |
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Lactic
Milk |
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Formic
Bee stings. Ants are the family formicae |
Take some baking soda, as we all did
as school kids, and add it to one of these acids and it will fizz
and bubble. When the bubbling stops, the acid is neutralized and
a weak organic acid salt is formed. For instance use citric acid
and baking soda and you get sodium citrate.
The oxalates are they only salts that
are poisonous but that does not mean that they are harmful to the
environment. Oxalic acid gives green leafy vegetables their bitterness
and oxalic acid salts are commonly found throughout nature. Ten
pounds of spinach has a lethal dose of oxalic acid. It is also the
reason that produce sellers remove the leaves from rhubarb –
rhubarb leaves contain a lethal dose of oxalic acid. In small quantities
the human body deals with the oxalates quite handily as the body
produces natural chelates (we’ll get to those later) that
render them harmless.
The most commonly used developers such
as ammonium citrate, potassium oxalate, sodium acetate, and sodium
citrate are quite harmless. In the opinion of Bostick & Sullivan
these in their unused state can be disposed of in a municipal sewage
system if well diluted.
Disposing of used developers
Platinum printers use the same developer over and over again. Most
printers will replenish by adding a small quantity of fresh developer
to replace the small amount carried off by each print. I know of
one printer who has been doing this to the same original developer
for over twenty years.
The only potential problem that might
occur with the disposal of used developers is the noble metals that
may still be in solution. These may be removed by adding a quantity
of steel wool to the developer in the quantity of 1 pad per gallon
of solution. Metallic iron will reduce out any noble metals into
their pure state. After sitting overnight, there might be a small
residue of platinum or palladium metal in the bottom. Pour off the
developer off the top and save the black metal in the bottom. The
steel wool may also be shiny from having been plated by the noble
metals in the developer.
Ferric Oxalate
Platinum printers use ferric oxalate as the light sensitive ingredient.
It is an oxalic acid salt like the potassium oxalate developer,
and as such it is also poisonous and like the developer, the body
can deal with it in small quantities. Ferric oxalate is also a weakly
bound chemical and will quickly decay to ferrous oxalate and then
to oxalic acid and ferric oxide (rust.)
The chelates
Platinum printers use a variety of different compounds to help dissolve
out the left over ferric oxalate. Since ferric oxalate is the first
cousin to rust, we use many of the same compounds that are used
to remove rust stains from pools and spas.
The most commonly used compound is called
EDTA. EDTA is used agriculturally as an aid to help plants absorb
iron from the soil.
Some printers use hydrochloric acid to
help the ferric oxalate dissolve. This is used in a very dilute
solution and is relatively harmless in this concentration.
Conclusion
Platinum and palladium printing is in my opinion probably saver
to the individual and environment than either the normal black and
white silver or color photography. It uses no chlorinated hydrocarbons
and the organic compounds that it uses are as stated above, the
reasonably safe weak organic acid salts.
To repeat: It must be noted that in all
cases, your local regulations have precedence!
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