View Full Version : Film Developer longevity testing

Henry Ambrose
20-Mar-2006, 16:04
I stumbled across this while looking for something else. Its a pretty interesting evaluation of developer longevity for those who might be wondering about this subject;

http://www.udmercy.edu/crna/agm/phenvitc.htm (http://www.udmercy.edu/crna/agm/phenvitc.htm" target="_blank)

Jay DeFehr
20-Mar-2006, 16:39
It would have been intersting to have included glycol/TEA solvent versions of the developers.


20-Mar-2006, 17:12
the results are in line with what you might predict. longevity of these solutions seems proportional to the concentration of sodium sulfite (also known as ***the preservative***). range was zero sulfite in the phenidone stock solution (very short life) to 100g/L for D-76 (long life). this conclusion isn't scientific (the study wasn't designed to test this hypothesis) ... but i'm surprised they make no mention of the correlation.

Henry Ambrose
20-Mar-2006, 18:27
Presented as just something to read and think about.

This subject comes up every so often and is usually settled by cries of "I use this and it lasts forever" and "that stuff goes off too quick for me". I don't consider this the last word but at least this guy actually compared head to head and wrote it up.

21-Mar-2006, 08:46
thanks for posting it ... i didn't mean to sound dismissive. just some comments off the top of my head.

makes me suspect i keep my developer around a few months too long.

Tom Hoskinson
21-Mar-2006, 09:32
The author (s) seem to be unaware of Pat Gainer's work (and the relevant Kodak patents) which discuss the ue of Glycols and Triethanolamine as developer solvents and preservatives.

Also, "Finally, I was surprised by how hard phenidone is to dissolve. I tried dissolving it in a small quantity of isopropyl alcohol, which was not particularly effective. Heat was less effective than I would have guessed before beginning. I had to stir phenidone for 7-10 minutes before it would dissolve, even with distilled water at 150-170 degrees F."

Actually, phenidone dissolves readily in:

1. anhydrous isopropyl alchohol and other alcohols (anhydrous alcohols are best for maximum solubility and solution stability).

2. Aqueous solutions of potassium or sodium metabisulfite.

3. Various Glycols, including Ethylene Glycol and Propylene Glycol

4. Triethanolamine.

21-Mar-2006, 22:35
do you have a link to any of pat gainer's work?

did he mention anything about glycols as a preservative?

i have used diethylene glycol as a solvent for phenidone. it works well. it's what sprint uses in their 10x developer concentrates. i'd be curious to know if has any preservative qualities.

Tom Hoskinson
21-Mar-2006, 22:59
Yes Paul, Pat Gainer just posted this short article on APUG (Analog Photography Users Group):

Dissolving metol in glycol.


Pat posts regularly on Apug and on the Azo Forum as well.

Pat also wrote several articles on this and related subjects for Photo Techniques.

You asked if diethylene glycol has preservative properties - the answer is Yes! It is a good solvent and it also protects the develping reagents from oxidation.

22-Mar-2006, 11:15
thanks, Tom. that's good news. i usually mix up more film developer than i need ... sounds like the solvent gives it more of a fighting chance of survival.