The DARKROOM COOKBOOK, Third Edition

NEGATIVE INTENSIFIERS
FORMULA #176
Chromium Intensifi er #1
*Potassium bichromate, 10% , 12.5 ml
Hydrochloric acid, concentrated, 0.3 ml
Water to make 100.0 ml
Formulas 305
* Potassium bichromate is an allergen to some people and a suspected carcinogen. See precautions
under potassium bichromate in Pharmacopoeia.
For instructions on chromium intensifi cation see Chapter 11, Photographic Reduction and
Intensifi cation.
Caution: Always add the hydrochloric acid to the water slowly, stirring constantly, and never
add the water to the acid.
FORMULA #177
Chromium Intensifi er #2
*Potassium bichromate, 10%, 12.5 ml
Hydrochloric acid, concentrated, 1.2 ml
Water to make 100.0 ml
* Potassium bichromate is an allergen to some people and a suspected carcinogen. See precautions
under potassium bichromate in Pharmacopoeia.
For instructions on chromium intensifi cation see Chapter 11, Photographic Reduction and
Intensifi cation.
Caution: Always add the hydrochloric acid to the water slowly, stirring constantly, and never
add the water to the acid.
FORMULA #178
Ilford In-3
Chromium Intensifi er
Bichromate stock solution:
*Potassium bichromate, 100.0 g
Distilled water to make 1.0 liter
* Potassium bichromate is an allergen to some people and a suspected carcinogen. See precautions
under potassium bichromate in Pharmacopoeia.