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Wednesday, July 26, 2017

Salt as a fixer is spreading

As soon as March 2012, I rediscovered salt as a possible alternative to known thiosulfates fixers.

A 300g/l solution of salt will fix normal B&W films in about 24 hours.

After that date, I started a series of tests in order to make the salt fixer faster.

I came to the conclusion that adding 2ml/liter of a 5% solution of household ammonia to the salt fixer, the time is reduced to as few as 2 hours. In this recipe I also included 2g/l of Potassium Bromide which also contributes to the speeding of the salt fixer. But it may be left away, if time may be longer than 2 hours, let us say 4 hours. Also Potassium Bromide is not a household stuff and this is actually the aim of the thing, no need of expensive products and hard to get!

It is already 5 years ago that I published the 'finding' and slowly this is spreading away.

Early recognized by the Caffenol Master Reinhold, that promoted some discussions about it in forums,  I am glad to see that my modest contribute to homemade film development is beeing announced here and there. I found it today at the fine blog of Profesora G. J. Yukavetsky.

My compliments and special thanks!

Thursday, July 13, 2017

Dignan 2-bath and Betadine

My last modification of the Dignan 2-bath developer in order to get better results, at room temperature, is as follows:

Bath A

500 ml water
9 g Sodium Sulfite
1 g Potassium Metabisulfite
11 g CD4
Water to make 1 liter

pH should be acid
Time duration: 10 minutes (or more)
Note: Keep bath A in a dark bottle to prevent oxidation and reusage

Bath B

500 ml water
25 g Potassium Carbonate
0,6g Potassium Bromide
Water to make 1 liter.

pH is aimed to be about 11.
Time duration: 10 minutes or longer with constant (non stop) agitation for less grain.
Bath B may be one shot or reusable. No rinse or wash between bath A and B.

After bath B, a stop bath with 40ml of Vinegar per liter water is good to prevent basic contamination of the bleach bath and fixer.

And now, which bleach bath is suitable? Ferric(III)-Ammonium EDTA based bleach is good and Ammonium Thiosulfate as fixer is also a good option. But there are some more alternatives like Ferricyanide and Copper Sulfate & Salt for the bleach and Sodium Thiosulfate (Hypo) for fixer.

What only few people know is that Povidone-Iodine (sold under the brand Betadine) may also be used as bleach. Using a 10% solution of Povidone-Iodine, it takes about one hour to act. Like other bleach baths, it also needs aeration to work better.

Some examples of photos developed with the modified Dignan 2-bath as above, bleached with Betadine and fixed with Sodium Thiosulfate based fixer. The fixer also needs much more time to act, also one hour.

Conclusion: Betadine (Povidone-Iodine) works very well (IR scanning didn't show any remaining silver) and Sodium Thiosulfate works well too, both need much more time than regular accepted bleach and fix baths.