Dave
Dilute the Dektol or PQ at 1 : 20. Give very long exposure ; try two
test strip in minutes, 1.2,3,4,5 (!) at F4 and F16 and compare the results
and let us know.
Cut the strip into three across the strip and develop for 45 secs. 1 M
and 1M 15 secs.
This should give you results for a range of processes; the shortest will
probably be best for gum.
With short development times drop the film face down onto the surface of
the developer and flip it over straight away. Give continuous agitation by
lifting one corner of the tray every second. Then rinse and fix in film
fix.
Terry