Quote Originally Posted by Photo Engineer View Post
Measuring viscous liquids by volume becomes tricky! Best to use a syringe from a pet store or vet, or use weight. PE
Funny you should mention weighing. I find myself weighing all liquids once I know their sg, as in the formula below. For me, it's more accurate.

Here's an interesting discovery:

The pH of a TEA-based developer changes much with temperature.

I know that pH changes with temperature, but I'm used to XTOL and my similar developers that use borate buffers. For them, the change in pH from 20C to 30C is .02 to .04, which is not significant. But when I replaced the borate with TEA, the pH-shift from 20C to 30C was .17, which is substantial. Here's the TEA-based developer I was testing:

80 g Sodium sulfite
8.3 g Ascorbic acid
13.6 g TEA-99%
0.2 g Dimezone-S
20 g Propylene glycol (to simulate a concentrate)
Water to 1 L
(I don't suggest you mix this. pH is too high at 20C and dev-times too short)

As temperature rises, the large pH-drop will partially offset the effect of the rise in temperature. I wonder if such a developer would allow users to be sloppy with temperature-control. Anyway, this aspect of TEA is nice to know about. As always, comments are welcome.

Mark Overton