Had to develop some FP4 accidentally rated at 400 asa for a friend. Best results were with HC110 Dil B, 12.5 minutes, agitate for first minute, then 15 sec's every minute there after. The usual stop and fixing routine.
You can add this to your oops developing times.
Thanks for the information, I work with both FP4 and Tri X 400. A few times I got things confused and exposed the FP4 at 400 too. I have not yet exposed the Tri X at 125....Now I try to keep the backs marked.
Thanks Eric. I also work with Tri X, HP5 and FP4. I haven't mixed them up yet but give me time.