What's wrong with my Foma RC paper?

Well done dcy on finally sorting the issue out. In the distant past I had a similar problem and like you I finally sorted the problem out by making some fresh D72. The original stock developer looked good, so I didn't consider this to be the problem initially. So, sometimes the answer is right there, waiting for that Dohhh! moment to happen.

As for E23, I have used it and it was easy as any to mix up, but I generally ignore formulas which say, 'Add 1/2 of the final liquid amount and mix the chemicals in'. I now use 2/3 to 3/4 of the warm / hot water listed, and have found all chemicals mix in fine then. The mixture is then finally topped up to the recommended amount.

The only thing with home-mixed E23, as you will quickly find out, is it's short shelf life. The same with film developer E76. After much reading, I am trying out a chelating agent, of which I presume the Adox Eco developer uses, to extend the developers lifespan.

As for named paper developers, I used Ilford MG for many years, before starting to mixing my own, and found it to be great, both in use and its storage life. In fact, I recently found a single one litre bottle of the concentrate tucked away at the back of a darkroom shelf. It had been decanted from a five litre bottle, which is how I buy / bought my fixers and developers, as you basically get two litres free, when the prices are compared between one and five litre containers. It must be about five plus years old and it still works like it was freshly bought! But I'll carry on mixing my own various developers and toners, for like you, I enjoy it as part of my photography.

Terry S

Don_ih said:

I actually meant are you sure that what you think is ascorbic acid is actually ascorbic acid?

Click to expand...

Ah. That makes a lot more sense.

Yes. I did consider that also and that is in fact a very strong possibility. This is in fact the #1 thing I wanted to improve about my process before I even begun. I'll explain: The product I used is actually a set of Vitamin C tablets that I got from the grocery store a year ago when I decided to make PC-TEA. That means that, while they are mostly ascorbic acid, they also have other ingredients such as a binding agent to keep the tablet together. I still used them because they're still mostly ascorbic acid and my PC-TEA worked well. So my plan was to finish off most of the bottle and then order a bag of pure ascorbic acid. The E-72 that I just made was enough for that, and I did order a bag. Anyway, it is possible that either some of the binding agents or an imperfection in how I ground the tablets down made it harder to dissolve.

dcy said:

Anyway, it is possible that either some of the binding agents or an imperfection in how I ground the tablets down made it harder to dissolve.

Click to expand...

The fillers are typically stuff like calcium carbonate - which virtually doesn't dissolve. So yeah, the stuff floating around was mostly just basically inert material anyway.

That solves the mystery. And the stuff works, so that's good.

I think it’s cool you found different papers react differently to the D-23 you mixed.

If you’d used regular premixed developer you’d never have run into that.

Maybe you can find the root cause, which will make you better at mixing your own. Maybe the pH was too low and you could’ve just adjusted something. Maybe it was the water.

Bill Burk said:

I think it’s cool you found different papers react differently to the D-23 you mixed.

If you’d used regular premixed developer you’d never have run into that.

Click to expand...

No no no. The original problem was with a premixed developer. I was using the Arista paper developer. Problem was probably that a half-empty bottle of concentrate has a shelf life shorter than a year.

Bill Burk said:

Maybe it was the water.

Click to expand...

FWIW, I use distilled water for everything except the final rinse.

dcy said:

FWIW, I use distilled water for everything except the final rinse.

Click to expand...

If it's any consolation, the water is virtually never the problem, anyway. Commercial chemistry is formulated in such a way as to be tolerant of a wide range of water quality, which means that plain tap water will generally work in most parts of the world except perhaps in very extreme cases with e.g. exceptionally high iron content. With DIY chemistry you can notice cloudiness in e.g. developers if you don't use a sequestering agent. This is generally harmless.

dcy said:

No no no. The original problem was with a premixed developer. I was using the Arista paper developer. Problem was probably that a half-empty bottle of concentrate has a shelf life shorter than a year.




FWIW, I use distilled water for everything except the final rinse.

Click to expand...

Ok, maybe mixing your own would have been better.

I use bottled water to make the stock, but tap water to mix working solution and stop bath and fix (from concentrate). All the water goes through a single stage filter but I just use the bottled water sparingly. But then the final rinse with Photo-Flo (for film) I use bottled water again because I don’t want water spots.

To clarify, by "bottled water" I assume you mean distilled or demineralized water, correct? The term 'bottled water' can also refer to water sold for human consumption, sometimes called 'mineral water'. This is often relatively rich in dissolved salts, depending on origin.

Bill Burk said:

Ok, maybe mixing your own would have been better.

Click to expand...

I could also have transferred the contents to a smaller glass bottle. I did not think of this at the time.

Bill Burk said:

But then the final rinse with Photo-Flo (for film) I use bottled water again because I don’t want water spots.

Click to expand...

For film I use tap water for the Ilford wash, and then one last rinse with distilled water and Photo-Flo. That's probably excessive, as either just Photo-Flo or distilled water should be enough on its own, but distilled water is cheap and I happier knowing I won't get water spots.