I am in chaotic cycle in many hobbies and going and coming back to photography.
I loved gum bichromate prints which looks like a water color hand paint.
But I will not do it with poison , no way.
Can you advise me a clean way ?
Mustafa Umut Sarac
Yes, send me your money (lots of it), and I will gladly send you clean gun fichromate pints. :0)
Sorry, but I don't think there is any other way to do it without the dichromate. Like many chemicals, its toxicity is probably overblown, but the risk is still there. Handle everything with care and you should be perfectly fine. Wear gloves when necessary, dissolve the powder in a well ventilated area (with a mask), and you should have nothing to worry about.
Sorry, I didn't mean to be rude in my post above, but think about what you are asking. Well, maybe there is a way; digital....
As E76 noted use care and you will be fine. When dichromate is in its dry form it is much more dangerous because you have to be careful of dust that can become airborne. Use a mask when weighting and mixing. Once in solution it is much safer to handle.
There is way. Clean, non-digital and well supported. Silkscreen water-based emulsions use other agent. Ecological, non-cancerogenous, more sensitive to light yellow powder. You mix it into emulsion just before you use it. I'm sure you'll get some information at your autotype dealer (http://www.macdermidautotype.com/ i think this is their site).
Share resources, discoveries and results
girls & guys, by the way: We have lots of problems in obtaining bichromate salts in Poland. Tones of paperwork, agency of national security has to be acknowledged (it is used to make bombs), you have also give a paper after you use it - a bill from someone who recycled it. Lots of phun. So I have 1kg in "secure place" :D Just in case :D
Though I no longer have the citation, tonnes of dichromate are dumped via industrial use to the environment daily. A fraction of a gram used to make a gum print is inconsequential by comparison. And, much of the waste water used by a hobbyist can be collected and reused, then the chrome salt converted to a less toxic trivalent chromium form before being disposed of as a precipitated solid waste.
I'm not sure if it is still made, but IIRC, Edwal tray cleaner was essentially dichromate solution and might be easier to obtain in that form in some countries.
Joe, that's potentially a golden piece of information. Obviously, handling a solution is easier than taking the necessary precautions to use the powder safely. Maybe an alternative would be to order a solution from Photographers' Formulary or Bostick and Sullivan, if they are willing?
Mustafa, there's risk to everything. And I'm glad you've looked into it for yourself and made a personal choice. It is much better to be informed than uninformed.
However, I don't mean to say dichromates are too dangerous and that everyone should avoid them. Everyone just needs to make a decision that works for themselves.
smieglitz... It is not big problem to remove bichromate safely for me (read below). It is a problem for our government.
One more thing, Mustafa:
You don't have to have "clear" solution, there may be some crystals in water, even 3/4 of jar you have it in may be filled with crystals and you just refill it with water.
You don't have to keep it in absolute darkness - when it got light it breaks into neutral green pigment, some other salts and oxygen (pigment is quite common chrome oxide olive green, very small particles, nearly safe in contact with skin, can be used to make gums too when you seize paper), so exposing to light all washing water and taking out the pigment may be sufficient in most cases.
When healthcare comes to my mind, dichromate is big piece of shit.
It is almost unable to hold it soluted in water in plastic containers. Holding it in liquid solution is much safer than in dust or crystal form, but you have to care of it too. And use glass with rubber plug (made of gum).
I have 0,5 l bottle left after novocaine solution found in abandoned hospital - it is made of thick glass with crude scale, it has rubber plug *and* aluminium cap on it - it is quite good (If bottlenecks interior and plug is dried every time after opening it of course). Any drop or liquid left anywhere (bottleneck, tools etc.) will dry and form crystals and the fun begins again.
Medical thick glass bottles are more suitable in my opinion, than casual photo soup bottles.