FP4+ requires less dev time than HP5+

elerion

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Ilford recommends more developing time for FP4 than for HP5, for most developers. Take Rodinal for instance. 9 vs 6 minutes, 1+25 for their box speeds.

I get the opposite results. FP4 requires less dev time for Rodinal, but also for Caffenol. When I develop both films in the same tank (Rodinal 1+25), FP4 comes out with a higher contrast, and pushed like one stop. Also, Rodinal states a dev time of 8 minutes for both films.

Any experiences which correlate or contradicts these results?
 
I use both films, expose at half box speed, and develop in Caffenol C-H(RS). FP4+ takes 12.5 minutes @ 20C, and HP5+ 15 minutes @ 20C.
 
My times @ 20C are:
  • Ilford DD-X 1+4 HP5+ 9:00 and FP4+ 9:30
  • D76 stock HP5+ 7:30 and FP4+ 8:30
So from my own experiences FP4+ can need a little bit more time but, of course, things could be different with Rodinal.
 
Thanks guys.
The strange fact is that ilford (which time charts seem accurate according many people) states 6 vs 9 min for FP4/HP5 in Rodinal, while I get almost the exact opposite. I repeated it quite a few times; same results. Too much difference to be a slight inaccuracy.
 
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