Phenidone / Ascorbic Acid developers : E-72 and PC-TEA

Alan Johnson said:

Your optional "12 teaspoons of pyrogallol" per liter in post 1must surely hold the record as the most toxic paper developer ever published on photrio. Where did that come from?

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Thank you for pointing it out. I did add a warning about the high toxicity. There are several sources presenting similar paper developers using high concentrations of pyrogallol.


I guess I "calculated" the high maximum values for Pyrogallol, to offset the lack of Catechol in the formula.
One of the formulas gives 5g or pyro and 10g or catechol, the other gives 10g or pyro and 10g or catechol.
So I arrived at 5g of pyro (minimal amount of pyro and no substitution for the catechol) to 20g of pyro (10g of pyro plus full substitution for the 10g or catechol).
Yes, I know, I am about to get lynched.

PS I would not advise going down this route, but I added it as an option, as it did seem to work to increase activity in my experimentation. Which was my original problem. But it completely defeats the goal of having a safe vit. C based developer.

I would gladly remove any mention of this nasty stuff, if I was still able to edit the original post.
{Moderator note: toxicity warning added/emphasized in original post}

measwel said:

I would gladly remove any mention of this nasty stuff, if I was still able to edit the original post.

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@measwel ,
I have added extra warning language in your original post.

I have used E-72 for many years now. I keep a solution of 2g phenidone in 100ml denatured alcohol on hand and mix a working solution directly and right before printing. I get at least a few days of tray life from it.

For film, I've never tried PC-TEA, but used PC-Glycol for several years. I've now used E-76 for a few years. I switched from PC-glycol because I can use published D-76 developing times and be about right. Again, I mix directly to a working solution.

I find the phenidone-alcohol solution keeps well for at least 18 months, and that it doesn't keep five years. I'm not sure when it becomes bad. The 18 month shelf life is plenty for me, 100ml typically lasts me less than a year. I pre-mix the alkalai part of the recipe, so to mix a working solution it's phenidone-alc, alkalai solution, vitamin C measured with a measuring spoon, and a bit of Benzotriazole.

I've never had mysterious developer failure. My non-expert theory is keep all of the components except the alkalai water-free until use.