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- Aug 20, 2006
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but the lower toxicity is one of the main points to switch from the dichromate. or at least it is for me, since i'm looking for something i can use in my improv-dim room with less of a headache.For the 2 chemicals I received samples of, and based on the MSDS sheets I received with them, I would say that handling them poses no greater risk to human health, than say, handling selenium toner powder or dichromate powders. Appropriate care should be taken to protect your eyes, skin, respiratory tract and other mucous membranes from airborne dust and direct contact. As always, it is up to the individual user to review all safety information regarding a specific chemical or process, and take all necessary measures to protect oneself.
--Greg
Any yellow stain?
Can anyone reading this thread explain the chemistry of clearing these prints, especially the role of the potassium permanganate? For reference, the formula can be found (there was a url link here which no longer exists).
--Greg
If your fixed-out FB paper was treated in a hardening fixer...[snip]...It therefore might be interesting to observe what happens with photo-paper that was fixed out in a non-hardening fixer.
It seems like we're transfering all of the health and environmental handling concerns from the dichromate to the permanganate.
If one of the goals is to come up with a carbon process with fewer potential risks to human health and the environment, it seems like an alternative [to a permangante] clearing solution should also be investigated. Would a strong hydrogen peroxide solution (say, 10%) serve a similar role?
--It's about 1/2 to 1 stop slower than the comparable dichromate-sensitized tissue, but with a much longer exposure scale (about log 3.0). This is 600-800 units on my NuArc. 800 units is about 20-25 minutes, which gets to be a little hot.
Geg
1 euro per gram is pretty good. The other EU supplier I had found was > 2 euro per gram.
does the original Ultrastable recipe contain other special ingrediënts like surfactants or conservation agents?
And how about sugar/glycerin/alcohol (amounts) or other plasticizers in the pigmented gelatin?
Kees
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