How can I tell if my Diafine is exhausted

I know that it has a reputation for lasting a long time, but nothing is forever. What are the signs that my Diafine is exhausted? I replenish "A" on a regular-ish basis, just to keep on top of fluid loss, but the "B" has been around for a while, and is now a lovely deep brown. How will I know that it is past its prime and need to be replaced or replenished? Will I see a loss of speed? Contrast? Anything? Do folks take a little of the "old brown" to get a new batch of "B" seasoned from the start, a la lith developers?

Thanks in advance, everyone.

I found that after developing umpteen films the B bath developed a funny sort of precipitation, oil -like, which clung to the film.

Hans

I keep mine until it develops sludge.

DBP said:

I keep mine until it develops sludge.

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I put a white coffee filter in a funnel and filter the sludge out of mine and just keep using it. Coming up on two years now...I dump it and mix up a new batch when "A" is about all gone. Dave

I suppose the best way to tell would be to take out some negatives that you processed when the batch was newly mixed and compare them to the negatives that you just process and see if they look underdeveloped. I use Diafine, but not often enough to exhaust it, so I'm just speculating but that's how I would test any developer that had some age on it.

- Randy

The Diafine A bath contains the developing reagents (including phenidone), keep it replenished. The phenidone can lose activity without causing any color change.

The Diafine B bath contains the alkali which activates the developing reagents in the A bath.

Hydroquinone carried over into the B bath from the A bath can oxidize and cause a brown or black color in the B bath. Film sensitizing dye and anti-halation dye can also accumulate in the B bath. However, the B bath will continue to work as long as its pH remains high enough.

You can always replace the Diafine B bath with a solution of Sodium Cabonate, Sodium Metaborate (or Borax) dissolved in water.