Originally Posted by John Cook
Are you talking about stock solutions going bad unpredictably? I've found the concentrate to be very stable even in partially filled jugs.
My practice is to mix only the amount of working solution you intend to consume immediatly.
I've had very good results with dilution B and sheet versions of Tri-X, exposing at an EI of 160. You can get into trouble with blocked highlights though. Bruce Barnbaum recommends a highly dilute mixture of dilution B to handle very contrasty scenes, he places his shadow values on Z IV. If I remember correctly dilution B is diluted 1:49 and about a 19 or 20 minute development at 68F is recommended. It works! I've used it.
Normally though my dilution B time is 5.5 minutes at 70F.