Down Under
Member
I know one printer who develops at 75º or warmer for 2 minutes--he feels the blacks hit max while leaving the whites clean. On the other hand, I know another printer who will develop for 7 minutes at room temperature for deep blacks. Both gentlemen make excellent fiber prints.
I'm with the two minute guy - at 71, life is too short to hover for seven minutes over a developing tray...
But entirely correct - the backs pop up first and the trick is to expose the print so it is complete in both lights and darks in the two minutes. Exposure for the highlights, pulled back a fraction, seems to do the trick for me, a technique that suits how I expose my negatives (a tad 'soft').
You mentioned FB and not RC papers. With RC, I did try longer development times way back when - in the '90s - and found I didn't really get much good contrast beyond a set time (this varied from two minutes with Multigrade to three minutes and a bit with the then-available Kodak papers) and ended up with mostly shades of gray I didn't care for. I varied my 'experiments' with full-strength developers and various dilutions. In 2003 I lucked into two new Jobo Duolab units hugely discounted by the Australian supplier and began processing at 24C in my home darkroom. Suddenly all of a sudden, everything changed for the better - I was getting more blacks and whites as well as the aforementioned shades of gray. At the same time, I moved my printing contrast (which had been fixed at paper grades/filtration 1.5-2.5 for several decades) to 3-3.5, and this also made a major lot of difference.
With FB, I've had none of these problems, even with my very ancient papers. With reasonably careful storage (all mine is refrigerated at 2C) the stuff will last for decades. I have old Kodak RB papers from th 1950s that print tolerably well, contrast can be somewhat all over the place from sheet to sheet, but this is part of the fun - not knowing what I'll get in the final result. I use FB entirely for an occasional sale 'art' print but mostly for personal and family prints anyway, the sorts of images that get put into albums and left for a century...
All experiments I should have done long before, but well, you know. We have ways of doing things, and as time passes and we get older, the comfort factor sets in.