Potassium Dichromate is toxic.

Note: Always add the acid to the water slowly whilst stirring. It is hazardous to add the water to the acid.

Working solution : 1+10 water.

Film, which should be hardened, is bleached until completely yellow-buff in colour, washed 5 mins., then redeveloped in ordinary print dev. for approx. 5 mins. Over-development is not possible. Rinse, fix and wash for 5 mins. Ensure that redev. is complete before fixing otherwise some of the image may be lost. Process can be repeated for greater effect.