Eric,
I have definitely found that a shorter exposure will produce a higher
contrast. I suspect that this may be due to the printing-out
characteristic of pt/pd. Sometimes I'll purposely move the printing
frame further from the light to increase exposure time and decrease
contrast.
This also becomes a problem for negatives of too low a contrast. The
contrast agent usually lengthens exposure time. The result is a fight
between a drive (by the printer) for higher contrast and a desire (by
the materials) for a lower contrast.
Other factors affecting precoated paper are humidity and time. I have
found that a precoated paper kept dry, cool, and dark will not produce
good results the next day. I even notice some degrading over half a
day. Coat only the paper that can be exposed in three to four hours.
Or better, coat each sheet only as needed.
Thanks for the info. on F.O.
Jeffrey D. Mathias