I have an old interest in the SDB process too...
PE's lists would be very welcome... I do dream though, that someway around the use of such low a pH could be sought and found... That would be the best thing that could come out of a focus group from my POV... Yes, I know I am dreaming. But if anyone has ideas....
But still used very low pH... correct?
Originally Posted by Photo Engineer
AFAIK, the reaction to cleave Azo dyes into their constituent parts requires a strong acid on the order of pH 1.0 or thereabouts, or LOTS of heat and a milder pH of about 3 - 4. (200 C) See the RD. I forget the details offhand. It has been nearly 40 years.
I remember Dye Chrome K2 chemistry used to make a kit that used a split bleach step. A C.C Phifer made it. Used it to control contrast..
Called the number thats listed in Ctein's Post exposure book, but no answer.
I still print Ilfochrome,have 100 sheets left. After that i will try something else
,its too much money if you can even get the chemistry.
Wish some one thought about this ten years ago,for if i could get a steady supply of the stuff, its all i would print...
Last week i printed my last sheet of pearl...
I have a stack of out of date Ilfochrome classic and rapid paper and the chemistry is nearly impossible to get in Ireland, so I'd definitely be interested in some chemical experimentation.
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Count me in too. I bought an old darkroom setup with a RT Ilfochrome processor and haven't had a chance to try it out. I have some frozen paper and an old P3 1 liter kit to pitch in to the testing if needed.
OK Folks... Interest is now falling off! I would like first to deal with those who are in the US. Certainly Nicholas, and perhaps akaa. I will PM everyone shortly. One point however...In my hands, outdated ilfochrome is perfectly good for making formula changes, and assessing the resulting effects. However, in general, beyond 1-2 years post-date, the color values may get a bit muddy, with a greater propensity for the often mentioned cross-over condition where the lower densities go cyan, and the shadows go reddish. Before you begin, those of you with old paper should have some idea of how it performs currently using standard chemistry. Fresh ilfochrome is preferrable for any final result....yet, most of you have expressed your respective levels of poverty. Please give this some thought!
Ingredients of p3x bleach
Potassium Iodide CAS 7681-11-0
3 Mercapto-1 Propanesulfonic Acid sodium salt 17636-10-1
2,3,6, Trimethylquinoxaline 17635-21-1
Sodium Iodide 7681-82-5
Sodium Bromide 7647-15-6
Sulphuric Acid 7664-93-9
Sulphonated Trialkylphosphine 86563-95-3
Sodium 3Nitrobenzenesulfonate 127-68-4
You are spot on schlger! Quinoxaline 7K is 2,3,6-trimethylquinoxaline...the active dye bleach catalyst. This is the molecule that I now synthesize (its effectively impossible to purchase this). Some items on this list are expressly required for the compounding format of the P3X concentrates, as well as the fact that the mixed solution will be used in roller transport mode with essentially open tanks.
If anyone has any paper expired ilfochrome paper for me to buy that would be awesome.