I have a quick question about exposure time...I am using oiled positives printed on a large format printer at kinko's (13x19). The black areas of the positives came out more of a dark gray, and I am concerned that light may be passing through this part of the positive during exposure.
I know from doing a wedge test that the proper exposure time for my setup/emulsion is right at about an hour. My question is this: if i were to stack two oiled positives together to get a darker positive, how much time should I add to the exposure as a % of my known exposure time to compensate for the stacking (i would assume that less light will pass through two positives than one).
thanks to anyone that can help,