In all the tests I've done and that my students have done (they had to do
two "variables tests" per semester, and drying method, being so easy and
definitive, was a favorite), heat drying *reduces* speed of the emulsion,
sometimes dramatically. I never did this in pl-pd, however, but would
expect likewise.
Most horrific in memory is a gum workshop I taught at Cooper Union, with
unfamiliar equipment. I asked the teacher what the range of the exposure
system was. The reply was 10 -15 minutes. So we put the first prints in at
12 minutes. They were totally fogged. Eventually it turned out that
exposure range was one to three minutes, tho by this time the workshop was
over. I realized in retrospect that this teacher habitually heat-dried gum
emulsion... In the workshop we air dried with an electric fan nearby.
The difference in speed isn't that marked in cyano and VDB, or let's say I
aven't made a study of the topic, but general impression from the
students' variables tests is that the difference in D-max and separation
ranges from noticeable to dramatic, in favor of air dried.
Judy