- Jun 16, 2005
- 4x5 Format
Evidently. But for what purpose? The argument I heard, and never verified in any way, was that the cadmium deliberately or by accident prolonged the product's life. Was this in fact the case? Out of all people in this thread, you're in the best position to say something about this.
You see, I wouldn't be surprised if it was there for a totally other reason, just like certain rare earths still play a role in sensitization in today's emulsions, because they apparently play a crucial role in how the silver-halide lattice creates developable sites.
It is all about competition for electrons. We know if certain rare earth metals are added when the grain is formed or grown we get a certain result. If reciprocity failure is less we assume an electron was captured and held in place. It is all theoretical based on experiments conducted to test a hypothesis. The proof is in the pudding; make the emulsion with and without the rare earth metal and study the result. Film builders run many, many designed experiments. Explanations provided after it was demonstrated in the laboratory. Combinations that are to be tested are determined by experimental investigation (educated guesses and Edisonian trial-and-error. "We don't know what works; but we know what doesn't work". Don't rule out "by accident". It doesn't matter how you found the material that works.