Soda Solvay instead sodium hydroxide

[ferod]

Hello everybody, i have a little problem, i use an formula of 2 bath dev. with (A) pyrocatechin, s.sulphite and (B) sodium hydroxide, now i had change the hydroxide (4.5g in 300ml) with soda Solvay (4.5g in 300ml) the result is the negative clean, no image or number and brand of film.
So somebody can help me for resolve this problem?

Thank you.

 

[Mike Wilde]

I sort of thought that soda solvay would be the solvay process of making sodium carbonate.

Sodium carbonate has a lower pH that which Hydroxide presents. Hope this may help.

I am not familar with your 2 bath process. I have done two bath d-76 in the past as a way to tame high dynamic range subjects.

I also use pyro, but my pyro recipe of choice is called PMK, and is and A and B stock solution mixed just prior to use. The A ia the devloping agets, being Pyro and Metol (with some sulfite, I think- it has been a few years since I mixed up the stock -it lasts a long time) , with the alkali being soduim metaborate, which offers a lower pH than the carbonate form.

So your mix should be viable. My experience with PMK pyro is that it is a slow developer; I have times that run to 14 minutes with the developer at warmer than 72F. Times at the usual 68F are longer still. So the change from hydroxide to carbonate, if that is what solvay is, may just need a longer development time, and warmer temp to compensate for the lower pH.

My only other thought is that the amount of alkali in 300mL seems a bit high to my experience. For full lithographic developers, also a plus B like D-85 the hydroxide I sem to think is only something like 5g/1000mL.

Sorry, I am answering from work and don't have reference books handy to further give ideas from.

 

[ferod]

Hi, Mike, thank you for your reply.
I will be explain my process
The dev. is a 2 bath separately, not mix before use
I have try with this quantity (1g, 3g, 4.5g and 7g in 300ml) so the result is still similar, nothing on the film, but i have use another dev.
" bath mix before use with 6g of Solvay in 300ml and it work well, so i can understand why when i use the 2 bath the film go to hell.
I hoper somebody can help me.
P.S. film is HP5@400iso

thanks

 

[gainer]

Can you test the pH of the second bath? I don't think that even a saturated solution of sodium carbonate will come up to the pH of 4.5 g NaOH in 300 ml. You might try a stronger concentration of the first solution.

Don't waste negatives on preliminary tests. A small piece of film developed in room light should turn black after a minute or so in the second bath. After you have achieved that, you can try a negative in your usual practice.