From: Sandy King (sanking@hubcap.clemson.edu)
Date: 12/22/00-09:08:37 PM Z
Any carbro sensitizer should work with gelabrome and there are dozens
in the literature, distinguished primarily between single bath and
two-bath solutions. The formula given with succinic acid is a
single-bath carbro sensitizer, not one formulated specifically for
gelabrome. And no, I don't believe you will be able to substitute the
succinic acid without making major modifications to the other
chemicals.
A couple of other single bath sensitizing formulas are given below.
Both have worked fine for me with carbro, as has the one with
succinic acid. The directions are for carbro but their use should be
straight forward with gelabrome. Be advised, however, that the carbro
chemistry is precariously balanced and small changes in dilution can
lead to disastrous results.
Sandy King
1) Devin A-B-C Single Solution Sensitizer
Stock Solution A
Ammonium Dichromate 15.0g
Potassium Ferricyanide 50.0g
Potassium Bromide 50g
Distilled water to make 1000ml
Stock Solution B
Chromic Acid 10g
Distilled water to make 1000ml
Stock Solution C (optional)
Formaldehyde 15ml
Distilled water to make 1000ml
For 1000ml of working solution take:
No. 1-Stock 200ml
No. 2-Stock 75-135 ml
No. 3-Stock 20ml
A very limited control of contrast is possible by varying the amount
of Stock Solution B, whereas 75ml gives maximum contrast, 135ml
lowest contrast. Too little of the B solution will result in bald
highlights. Immerse the pigment tissue in the working solution (at
60-65° (15-18C)) and soak for three minutes before squeegeeing on to
the bromide. Leave the pigment and bromide in contact for fifteen
minutes. Discard the working bath after use.
2) Autotype Single-Solution Sensitizer
Stock Solution A
Potassium Bromide 48g
Potassium Ferricyanide 48g
Potassium Bromide 48g
Distilled water to make 1000ml
Stock Solution B
Chromic Acid 17g
Chrome Alum 33g
Distilled water to make 1000ml
For 1000ml of working solution take:
Stock Solution A 240ml
Stock Solution B 30ml
Water to make 1000ml
Soak tissue in water at 65° (18C) or less for two minutes. Drain
tissue for 20-30 seconds and immerse for one minute in the combined
working solution before squeegeeing the pigment and bromide together.
Leave tissue in contact with bromide for ten minutes. Discard working
bath after use.
>Hello!
>
>In the book HISTORIC PHOTOGRAPHIC PROCESSES it give a formula for
>Gelabrome sensitizer (below). It mention there are two bath
>sensitizers as well as variations on the single bath. My plan is to
>coat art paper with Silver Print liquid emulsion. I'd appreciate any
>other sensitizer formulas and comments which may be best.
>
>Also, is the a substitute for Succinic acid?
>
>SENSITIZER:
>
>POT. DICHRO. 12g
>POT. FERRI 16g
>POT. BROM. 8 g
>SUCCINIC ACID 2.5g
>POT. ALUM 1g
>WATER TO 1 liter
>
>Thanks!
>
>Mac
>
>
>
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