حمام الإيقاف .. كتاب التصوير الملون ، الكاتب عبد الفتاح رياض

P As in the case of “black and white” photography, the stop bath for color photography is a weak acid solution also containing acetic acid and Soduim Acetate. And the pH should not be less than (1) (H Value) and not more than 06. We have already mentioned the possibility of combining a suspension bath with an anorexia with an increase in hardness all in one solution (p. 186).

Stop Bath

It is usual to treat the image in this solution for about five minutes, followed by washing with water for ten minutes to remove all traces of it. We see in the following table on page (192) examples of the composition of suspension solutions, whether alone or mixed with stabilization solutions with an increase in hardness. Or with fixing solutions only, bleaching bath solutions, etc

Potassium fricyanide salt solution may be used alone, or one of the salts that work to regulate the degree of acidity or alkalinity (Value) may be added to it.

for him

(1) is actually the negative logarithmic value of the hydrogen ion concentration (P.H Value). For more information, please refer to the book “Development, Printing and Enlargement” by the author. (I) first edition. Publisher Anglo Egyptian Bookshop - 165 Mohamed Farid Street, Cairo. s

The bleaching process takes about (5 minutes), followed by another five minutes of washing with water, then fixation with hypo. This stabilizing solution may be a solution of sodium thiosulfate (hypo) alone, or mixed with a solution to increase hardness in addition to pH-regulating agents.

Although it is possible to simplify the work by combining two salt solutions that perform the whitening and stabilization processes together, as if we combined the hypo and fricyanide salt), but it is certain that the final solution will not have the ability to stay for a long time without deterioration, as is observed in the density reduction solution known as: Farmer's reducer), and that is why it is usually used in bleaching solutions (needed in the stages of colored negative presentation, with solutions that carry fricyanide salt. In the following table are examples of this, examples of the composition of bleaching solutions

whitening bath

A whitening bath and an acid hardness bleaching bath, PH 5.2

PH 7,8 alkaline

salts

acidic PH. 5,2

40 15

Potassium bromide Sodium Phosphate basic

Potassium Ferric yanide. Potassium bromide

80 grams

Sodium Phosphate Sodium Bisulfate

(

20 Ir

Sodium acetate (powder).

Sod. bisulphate

boric acid

Boric Acid Pot. Alum

potassium alum. The solution is water to make volume

Water

1000 cm

name 3

Notes: 1) It is recommended to use the alkaline bleaching bath shown in the last column when treating Kodak Kodacolor films - Ectachlor (2) We took the above table from the following reference, Ecta Chrome - P. 298 Jacobson - Developing, 15th edit.

However, there are other fixing and bleaching solutions together that are used in the processes of displaying colored positive images and prints and depend on the use of ferric salts mixed with a salt symbolized by EDTA, which are the initial letters of the following salt: