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Monday, February 20, 2012

More CD-4, please!

Like I said before, the experiment using first a more concentrated bath of CD-4 during 5 minutes, followed by development in Caffenol 10 minutes, gave the best results until now, after I started using CD-4 powder!

I made a bath of 3% solution of CD-4 and some drops of lemon to prevent oxidation. This bath, lasting 5 minutes, the time may be exceeded without over-development, is made «at room temperature» . After that, and without  rinsing, a 500 ml bath of Caffenol made of 7 g (1 tsp) Sodium Carbonate, aka washing soda, and 14 g soluble coffee (4 tsp) lasting 10 minutes at 38 ºC. Maybe this bath can be shortened. After this, I fixed the film to see how it was. Very black silver. Then I bleached and fixed again to complete the process. And that is all. The Bleach was like previous made of Potassium Dichromate and Sulfuric Acid and the Fixer is the common one, Ammonium Thiosulfate.

And here are the photos





Actualization

Resuming, the normal procedure should be:


Bath
Duration /min.
Temperature / ºC
Obs.
CD-4
5
R.T.
First minute agitation
Caffenol
10
38
First minute agitation
Rinse
1
Warm from tap
3 times fill
Bleach
2
30-38
Continuos agitation
Rinse
1
Warm from tap
3 times fill
Fixer
5
20-30
First minute agitation
Washing
30
R.T.
3 times fill and then take from tank and leave in water
Dry
90 min.
R.T.



Formulary:

Developer (H. Sousa, 2012):

Bath A - 3% solution of CD-4 (CAS n.º 25646-77-9) with some drops of lemon juice to prevent oxidation
Bath B - 7 g soda + 14 g soluble coffee + water to make 500 ml

Bleach (Franz Dietrich ,1988)
9,5 g Potassium Dichromate, CAS number 7778-50-912 ml Sulfuric Acid Concentrate
Water to make 1000 ml
Diluted 1:3

Fixer (universal formula)
160ml Ammonium Thiosulfate 60%, CAS number 7783-18-8Water to make 1000 ml

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