What is the shelf life of stock solution PMK?

[8x10 Masterview]

Around 1993 I made about half gallon of PMK stock solution. They have been stored in photo chemical approved plastic (I think HDPE) bottles and now wish I had used glass bottles instead. I last used the developer in 1998 and it worked fine. Now that I'm slowly getting back into photography, I got to wondering what the shelf life of the stock PMK solution is. Quite awhile back Gordon Hutchings told me it would last many years. But how many years? :confused:

[percepts]

Around 1993 I made about half gallon of PMK stock solution. They have been stored in photo chemical approved plastic (I think HDPE) bottles and now wish I had used glass bottles instead. I last used the developer in 1998 and it worked fine. Now that I'm slowly getting back into photography, I got to wondering what the shelf life of the stock PMK solution is. Quite awhile back Gordon Hutchings told me it would last many years. But how many years? :confused:

Well try it on some film and if it works you'll know it is as many as it has been since you mixed it.

[8x10 Masterview]

Good idea. A few test shots and run 'em through the developer and see what happens. It won't surprise me if it works as well as the day I made it. I'd like to report back that my 16 year old PMK works just fine! :)

[percepts]

Good idea. A few test shots and run 'em through the developer and see what happens. It won't surprise me if it works as well as the day I made it. I'd like to report back that my 16 year old PMK works just fine! :)
exactly.

[Allen in Montreal]

I mixed up some 15 year old PMK a few weeks ago,
it stained my plexi measuring container,
it was about 3 stops thin,
it did not stain in the classic tone, but looked like a red toner had been used.

I bet it would have scanned ok if I had doubled the normal development time and done a split development.
But I dumped the rest of the left over kits. :mad:

[kev curry]

Stock solution A should be ''pale yellow'' in colour according to Hutchings. When you mix working solution A and B together there is an immediate colour change from... ''grey green to pale amber. This is an important visual check of solution activity. If there is no colour change, something is wrong''. GH

You should also closely check solution B. The sodium metaborate in B is very prone to forming crystals (precipitation). This has a significant effect on contrast. It might be possible to redissolve the sod/met back into solution by heating and vigorous shaking. My own B sol... grew crystals after a year or so and they proved difficult to dissolve.

[Greg Blank]

Good info, accurate to my experience, however I would just plain pitch the solution B if not used in 9 months. B is too cheap not to mix more frequently as needed, A however should last at least several years if tightly stoppered.


Stock solution A should be ''pale yellow'' in colour according to Hutchings. When you mix working solution A and B together there is an immediate colour change from... ''grey green to pale amber. This is an important visual check of solution activity. If there is no colour change, something is wrong''. GH

You should also closely check solution B. The sodium metaborate in B is very prone to forming crystals (precipitation). This has a significant effect on contrast. It might be possible to redissolve the sod/met back into solution by heating and vigorous shaking. My own B sol... grew crystals after a year or so and they proved difficult to dissolve.