FX-55 Developer: Pre-packaging the "B" powders?

I'm very intrigued by FX-55 and have mixed up a batch of the "A" solution. I'm wondering if there's any detriment to pre-measuring the "B" chemicals and storing them combined in individual sealed plastic bags until use. That way I can pre-measure everything and then at development time simply:

-> Dilute Solution A 1+9
-> Pop open a pre-measured package of the "B" powders and mix them into the dilute "A" solution.
-> Pour into the tank and start developing.

So I guess I'm asking if there's any problems storing the pre-measured:

1.3g of Sodium Ascorbate
0.1g of Phenidone

in sealed plastic packages. Will these two chemicals interact in any detrimental way in powdered form when stored together?

In solution in water exposed to air and in absence of sulfite, sodium ascorbate slowly oxidizes >yellow>orange>brown.The rate at which your mixture oxidizes probably depends on how damp it gets and how much oxygen gets to it. It might be possible to make a test to see at what color the activity of your powder is no longer satisfactory but I have never seen any such results.

FX-55 was taken off the market because Paterson never correctly addressed the cause of the "sudden death" syndrome that ascorbate developers sometimes experience. There are better formulations available that contain chelating agents to prevent the problem.

Another approach suggested by Pat Gainer is to store the part B as a liquid concentrate. Here's the link:

(there was a url link here which no longer exists)

Mark Overton

Gerald C Koch said:

FX-55 was taken off the market because Paterson never correctly addressed the cause of the "sudden death" syndrome that ascorbate developers sometimes experience. There are better formulations available that contain chelating agents to prevent the problem.

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If I'm not mistaken it was FX-50, not FX-55, that was sold by Paterson and subsequently taking off the market. Geoffrey Crawley's response to this was to publish FX-55, a similar formula that keeps the Phenidone and Ascorbate separate from the other solution ingredients until development time. This effectively gave Solution A an unlimited lifetime and eliminated any type "sudden death syndrome" because the complete solution was never mixed until just before use.

I'm looking to optimize the "mixing just before use" scenario. As it sits right now, I'd have to pull out my scales and measure the two "B" chemicals every time at development time. I'd like to do that ahead of time and make little sealed packages of the two combined "B" chemicals that I can just open and mix with the diluted "A" solution at development time. I'm trying to find out if the Phenidone and Ascorbate will react in any detrimental way if stored together as powder in sealed plastic bags (i.e. air-induced oxidation should not be a problem).

Alan Johnson said:

In solution in water exposed to air and in absence of sulfite, sodium ascorbate slowly oxidizes >yellow>orange>brown.The rate at which your mixture oxidizes probably depends on how damp it gets and how much oxygen gets to it. It might be possible to make a test to see at what color the activity of your powder is no longer satisfactory but I have never seen any such results.

Click to expand...

Hypothetically any air-induced oxidation possibilities would be eliminated by storing the combined powders in small sealed plastic bags.

timhenrion said:

Hypothetically any air-induced oxidation possibilities would be eliminated by storing the combined powders in small sealed plastic bags.

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Actually, oxygen atoms can pass through most plastics. A few plastics, such as PET (aka PETE) are good O2-blockers, but most are not. But the good news is that these powders last a long time in the bottles that contain (and pass) O2, so O2 in air is probably not a problem.

That leaves the question of whether ascorbate and Phenidone damage each other in storage. I suspect you'll be fine. BTW, consider storing the little plastic bags in the freezer where they'll probably last for years.

Another idea is to dissolve a larger quantity of both chemicals into propylene glycol, heated to 70C-75C. Store the bottle in the freezer. I'm doing this with a concentrated developer I've designed. However, I know by experience that propylene glycol affects development, so dev-times will probably change.

Mark Overton

Your right it was FX-50 and was sold as two solutions A and B. This idea didn't work because the sudden death was caused by the Fenton reaction.

Solid Phenidone does not keep well when exposed to air. I had 250 g go to black tar in the original plastic jar it was sold in. An expensive lesson. However Phenidone keeps very well in a glass bottle.