Ian; I agree totally.
I would add the Lead and Mercury to that list, but also might mention that the small amounts of any of these used by individuals would pose no problem, as we commonly use them in other formulas for other purposes such as intensifiers and the like. In fact, the amount of Mercury used would be less than that used in a Mercury intensifier, I would think.
One of the problems with Agfa formulas is the use of a sulfur restrainer for stabilization. I have trouble with this, as it crystallizes in water and forms coating defects. I also find that Agfa formulas use a sulfite containing overcoat, and use egg white in the formulas to assist in gloss.
Many of these little things give the old materials their unique look which is difficult to reproduce in modern formulas. OTOH, modern baryta obviates their use in some cases or would inhibit their usefulness.
An example is the egg white, used to enhance gloss. Modern baryta is thicker and well calendered to give better gloss. Then again, modern baryta has fewer oxidizing agents and may not need the added sulfite.
This is part and parcel of the problems I'm facing and what I'm working on. It is also a problem for any non-chemist in seeing the formulas as written. They just don't work if you follow the instructions.
I would also add that many of the formulas are intentionally misleading as read. The people who passed on the formulas (Army personnel) were not engineers or chemists, and therefore the formulas were incomplete containing many comments such as "unbekannt" or 'unknown' in English and these gaps were not investigated or reported on.
Agfa had the habit of having unknown materials used, or keeping parts of the formulas secret back then, just as Kodak does to this day.
PE |