Friday Tip - Why we can't and why we can use Ascorbic Acid with our FX-55 developer
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- Опубликовано: 3 авг 2024
- Crawley's FX-55 is normally made with sodium ascorbate but sometimes that's hard to get our we have ascorbic acid on hand. Well, this video describes how I can use my ascorbic acid with FX-55 easily without needing TEA or any other chemical but common sodium bicarbonate (baking soda).
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Excellent tip; I did not know about this.
Useful video and well explained as always
I think sodium carbonate with ascorbic acid makes some carbonic acid (that decomposes to water and CO2). The reason you need to wait for a bit is to let disolved CO2 escape. (If you used a different base like NaOH you'd no need for the wait for that reason and with such a strong base, you would probably need no excess).
You need a bit "excess" of carbonate because all the buffering effects where some reacts to bicarbonate taking only one proton instead of two like with carbonic acid. After all, it is a equilibrium with acid - bicarbonate -carbonate and especially bicarbonate is rather weak base and will not react quantitatively like stronger bases would.
I've found this recipe interesting. I'm going to try that out when I get some of the missing items I already ordered.
Interesting. Yes, give it a try, works very well.
Great video. I will order the chemicals and try it. How does FX-55 compare with Xtol?
Sharper
Very interesting. I tried some Vit C-based developers in the past but wasn't too impressed: too flat. But then I wondered whether the stuff I bought in my local pharmacy, L-ascorbic acid, was of the right kind. Perhaps not. Eventually I made my own Pyrocat-MC and that works very nicely indeed with ascorbic acid. I understand that it acts both as a developing agent and an anti-oxidant. Would sodium ascorbate also serve both functions?
Sodium ascorbate does indeed work as a developing agent and antioxidant (although FX-55 also has sulphite for that job). Sodium ascorbate also regenerates the phenidone like hydroquinone would have in the past - this too is done by ascorbic acid in other developers. Ascorbate doesn't dissolve in PG, TEA or other organic solvents but does well in water. As I mentioned it's almost neutral so doesn't effect a developers PH much. Ascorbic acid, OTOH is easily dissolved in organic solvents so is useful for PG Pyrocat developers, PC-TEA and 510-Pyro. These are formulated to correct the PH swing. After much use and testing I personally prefer the tonal qualities of sodium ascorbate. That is not to say the other developers are inferior, they have their own look and that's ok. I've always liked 510 and Pyrocat very much. But I find it interesting that there seems to be a difference. It could be that Crawley just got the perfect PH for sodium ascorbate with phenidone I suppose - he knew his stuff. Must say, I am enjoying not wearing gloves again with FX-55. It's very safe.
I experienced flat negs too with other vitamin-c developers in the past. I'd been using Xtol and was impressed by it. But trying to make my own like Mytol, E-76, and others never pleased me. They performed poorly for some reason and were thin and flat. It was a revelation to see my first FX-55 negatives. They were beautiful. Very slightly grainier than Xtol (lower sulphite) but sharper with wonderful contrast. I've preferred it ever since. It's totally dependable.
Hi! What is the shelf life of this solution?
Make it shortly before use. It's probably fine for half an hour or so.