Originally Posted by
Vaughn
A little better test is to do the exact same thing, but give the piece of whatever you are working a slight over-all even exposure, then put the coin on it, etc. This will elimimate the possbility of a low-level exposure that is below the threshold of the paper or film, but still might have an effect (sort of like uncontrolled flashing). I did this test for the university darkroom and pinned the results on the board. Nothing like hard visible evidence to why one does not leave paper laying around in the 'dark' for too long!