Quote Originally Posted by Photo Engineer View Post
Your developer is overdoing things and should have less buffer.
Thanks for the response. That dev has both high buffering and a large AA/Phenidone ratio, so I'm thinking of running experiments (evenings...) to separate those two factors. "Overdoing things". The purpose of that was to tolerate errors in volumemetric sulfite-measurement, and that made me think of...

----- Here's an idea for measurement -----

I thought of a way to accurately measure sodium sulfite by volume, using a typical little beaker or medicine cup:

Step 1: Pour the correct amount of liquid concentrate into the cup (up to a fill-line).
Step 2: Add sulfite until the liquid reaches a second higher fill-line.
Step 3: Pour the cup into the main beaker containing water and mix.

This works because the liquid drives out the air between the sulfite particles, so you're only measuring the volume of solid. I tried this using only propylene glycol (PG) in a graduated beaker. I first poured in some PG, then added a known weight of sulfite, and measured the level. This let me measure the specific gravity of sulfite, and it was accurate within 1%! Success! Except...
The problem with this method is the sodium sulfite becomes a sticky glob in the bottom of the cup, perhaps due to trace water in the PG. It won't pour out, and must be helped with a popsicle-stick or somesuch. To get it all out, the little cup should then be rinsed in the beaker (dipped a few times). Would folks be willing to do this?

----- Here's a 2-bath idea -----

Since these developers consist of concentrate and separate sulfite, I realized they could also do double-duty as two-bath developers. A normal A-then-B development would be too thin, so you'd cycle back and forth between A-bath and B-bath a few times, spending 2-3 minutes in each bath. You should get compensating development typical of two-baths.

Cycling back and forth will contaminate each bath a little, but that won't matter because these developers are one-shot. Also, you'll need to mix say 50% more dev in each bath, and develop using the A-B cycling for a longer total time.
It would be appealing to have one developer that can be used either as a conventional single-bath or as a two-bath.

I've got more ideas than time to experiment with them. Retirement is sounding good!
Comments on all this are encouraged.

Mark Overton