View Full Version : Shelf life of PMK

Bill Kumpf
15-Apr-2011, 12:54
Is there a way to tell when the A & B components of PMK go bad?

Thanks in advance.............

Peter Lewin
15-Apr-2011, 19:22
If you mix a batch, it should immediately turn to the color of straw (yellowish); if you don't get the color change, the developer is dead. That said, I just started developing again after a lapse of almost 3 years, and my PMK was good as new. I believe the shelf life is something like 10 years and counting.

Drew Wiley
16-Apr-2011, 10:13
I store the separate solutions in amber glass bottles. Even a tiny bit left in each
bottles mixes and perform perfectly. Storage properties of PMK are excellent.

Doremus Scudder
18-Apr-2011, 04:28
The "B" solution will keep almost forever. The "A" solution is bad if it is badly oxidized and turns dark brown. As long as it is straw colored, it is good. Also, look for the color change that happens immediately on mixing the working solution. If that doesn't happen, something is wrong. If all the above are in order, your developer is fine.

I've had a very small amount of the "A" solution go bad once in many years of using PMK. Normally I use the developer to the very end, even when the last was just a small amount in a rather large bottle.

Hope this helps,

Doremus Scudder

Fred L
18-Apr-2011, 04:53
The A solution of my 3 year old (give or take) PMK is toasted and has that lovely deep reddish colour. Odd thing is, I have some other PMK that's 7 years old and it's still good. Does the A go off from oxidation or trace contamination somehow ?

Bill Kumpf
18-Apr-2011, 10:12
I have stored the solutions in glass amber bottles using marbles to replaced used solutions. When mixed the color was darker than I remembered when the chemicals were new. Also the developed film had less constrast.

I am replacing it with new.......


Fred L
18-Apr-2011, 11:03
The shop I normally get PMK from will no longer be carrying it so I was told this morning. Seems they need to order a ton of it and well I guess me and the few others who buy it weren't using enough of it. Guess it's all coming across the border from now on.