Gary, where were you in 1972 when my C-22 lab would send back 1 or 2 rolls of color negs perfectly developed, but larger numbers of rolls would come back low contrast and underdeveloped. Turned out huge stacks of Nikkor reels in the soup were pulling down the developer temperature far more than just a few rolls. Caused me some serious pain. The last regularly scheduled E6 lab in Albuquerque turned into a place where you could buy hub caps that kept spinning even when the tires weren't.
Well Bill, in 1972 I was still working at the custom lab I started with in '68 in Toronto and was managing then as well. The lab owner was a very well trained and knowledgeable fellow and I learned a lot form him. He set up two sink lines, one for E3 trans process and another for C22 neg film. Made his own baskets and holders for the E3 line with PVC material. Built in agitation lines, nitrogen and oxygen and immersion heaters for for both systems. For the E3, 20 gallon tanks, which, due to the volume of chemical would hold the temperature very nicely and then a little boost between runs. The first three tanks were in the darkroom and then the baskets were taken out into the light for the rest of the process. The first procedure after the darkroom was to remove each holder from the basket and make sure the film was completely exposed to a flood light. That was the reversal part of the process, which of course was eventually taken over by a reversal agent in the automated systems. Hmmm...funny how all of this stuff comes back after all these years, as if it were yesterday. For the C22 line we used 3 gallon stainless steel tanks in a water bath and Nikkor reels as well, but again the temperature was maintained very closely. When I set up my own lab in '74 I took what I had learned with me and it did me well for quite a long time, but of course eventually more sophisticated equipment was the only answer.
That's all history now, but I hope some of it will still be taught in the courses that the latest generation of "photographer wannabes" are involved with these days. Not all of it obviously, but enough to let them know where all of the Photoshop terminology comes from. I was using an unsharp mask technique to increase the apparent sharpness in B&W printing before Photoshop came into existence. When I show someone a B&W print that I made several years ago with that technique they inevitably make a reference to the fact that it was done in PS or Lightroom using Unsharp Mask. I then explain that no, it was created not in Lightroom but in a Darkroom with an actual "Unsharp Mask". In those days we used what was available to get the results we wanted, and for the most part it worked very well.
Well, it's getting late and my eyes are starting to droop somewhat from staring at this display. That and the fact that I tend to ramble on too much. So to make a long story short.....woops, it's too late for that. I have a feeling you can identify with much of what I have written here Bill, so I hope you don't mind my ramblings tonight. Have a great Christmas and a Happy, Healthy and Prosperous New Year. That goes out to Bill and Andrew and all on this thread.
Merry Christmas to all, and to ALL and GOOD NIGHT ; ^)