I'm sure someone out there in traditional darkroom land has done this, but I've just now discovered this on my own. I'm in Sunny Southern California. Make that HOT! Sunny Southern California. I was mixing up developer for black and white print processing. The cold water in my darkroom comes out at over 80 degrees. I added a few handfuls of ice to the water before mixing it into the Dektol. Thus getting it all down to 68 degrees. After 2 prints I checked the temperature and it was up to 75. I didn't want to add more ice because it would dilute the developer. So I thought for awhile. Hmmm . . . Went to the fridge and took out a frozen gel pack that I use to ice down sore muscles. Placed it under the developer tray. Five minutes later the temp in the tray was 68 and held there until my print session was done. Cool huh?! (Pun intended). An added but unplanned benefit was that it made the tray self rocking. Didn't have to lift one side and then the other. Just gently push down one side and then the opposite side. Easy. I'm so proud of myself.

Can I patent that?