CatPTEA

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andynguyen
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Joined: Wed Feb 24, 2016 8:45 pm

CatPTEA

Post by andynguyen »

Hi peeps,



I mixed up CatPTEA as per formula given in Darkroom Cookbook. Actually i wanted to do PCTEA, but ascorbic has yet to come in, so i settled for CatPTEA instead.

I dev-ed the film in CatPTEA 1+100 for 7.5 mins & it came out almost blank, to my surprise.

A quick search led me to some other forum where people states that TEA pH is not high enough to activate catechin.

To verify this, I mixed a so-called part B of carbonate, something like the 2-tablespoon of soda formula of Barry Thornton. & add to the CatPTEA. The new mixture, then, behaved as expected, yielded negative with good contrast, albeit with slightly coarse grain. I've tried it with several types of film & get good results with 7.5 min dev time @ 20C.

I, then, have a question: what modification can i make to this mix to control the grain?
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sanchell
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CatPTEA

Post by sanchell »

Perhaps the simplest method for reducing grain is the addition of sodium sulfite, as you suggested elsewhere. I would suggest mixing a 10% solution of sulfite and adding 10 ml to 1 Liter of working solution. Develop, inspect, add 10 ml more if the results aren't satisfactory, repeat.



10% solution: 100 grams sulfite to 1 liter of water



For testing I would expose one roll of 36 to a single subject, using a tripod. Include areas that you can judge grain, such as some blue sky, perhaps a gray card, perhaps a model for flesh tones (use a self-timer if you need to), etc. This will give you an idea of the gray scale as well as grain. If your only concern is grain photograph a clear blue sky (bald-headed sky as Ansel liked to call it). Nothing will allow you to compare grain better than a bald-headed sky - bit you won't have a gray scale to compare.



In the darkroom cut the roll into 4 equal parts and develop one at a time, adding sulfite as needed.
Do it in the Dark,



Steve Anchell
andynguyen
Posts: 37
Joined: Wed Feb 24, 2016 8:45 pm

CatPTEA

Post by andynguyen »

thank you Steve! As I break it down: 10ml of 10% solution means 1gr of sulfite in 1L of developer. would it be too little compared to, say, 100gr of sulfite per 1L of D76?... i'm thinking of going into the 10gr/L range for trial. I will do & update.
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sanchell
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Post by sanchell »

More would be fine. I didn't think it through all the way. You'll probably end up with 60 - 80 grams of sulfite to see a difference, so go ahead and start with as much as 30 g/L. BTW, once you have the results you want, be sure to share the formula on the forum. :-)
Do it in the Dark,



Steve Anchell
andynguyen
Posts: 37
Joined: Wed Feb 24, 2016 8:45 pm

CatPTEA

Post by andynguyen »

I've tried it, some 2 tea-spoon (which i guess amounts to around 15-20gr/L) seems to do the trick. Grain appears less offensive, especially in the highlight. This contradicts what is said that only beyond 50gr/L would sulfite shows solvent effect.



But well, Patrick Gainer had this to say: “I am doing some experiments with D-76 to try to separate out fact from fiction. I have varied the sulfite concentration while keeping everything else the same, and I have kept the sulfite constant while changing the dilution of the rest. The results are interesting. There's no noticeable difference in graininess in 30 power enlargements between 25 and 100 grams/liter of sodium sulfite. Go figure. I know that infectious development is very important to process photography of line art. It requires minimum sulfite, which is why all those developers are kept in two parts. I believe that Rodinal has some of the characteristics of a process developer and that its grain is not necessarily the 'full, unetched grain' that is often declared, but the result of grain growth through this infectious development. In a manner of speaking, all development is infectious. It begins with an invisible latent image in only a molecule or two in a crystal and spreads to the rest of the crystal. Sulfite inhibits this growth.”



I'll do further testing to ascertain this..



Btw, upon further calculation, CatPTEA (1+100) contains a surprisingly minute amount of developer (0.01g Cat & 0.005gr Phenidone per L) and yet it yields a dense & contrasty negative. is this superadditivity in play?
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