Carolyn, Perhaps you need more heat from your iron. I recently gave a
workshop in photo etching and had the students bring their own irons.
It was surprising how much variation there was in the temperatures of
the irons.
Most of the participants found that they needed a much higher
setting than they thought in order to get a good transfer of the
design. Most of them took about 5 minutes before they got results,
Put a piece of paper toweling between the iron and the PNP, as a
precaution just in case you get the iron too hot—although I never
had this happen, even though I use the iron set on high. I keep the
iron moving constantly.
Try raising the heat of the iron be increments. PNP takes a lot of
heat.
Alma