Formula for copper based rehalogenating bleach

[Mark Fisher]

I am looking for a copper based bleach to use with second pass lith printing. I can't find my Tim Rudman lith book (ugh!) and I looked all over the web and I can't seem to find what I am looking for. I used some potassium ferricyanide bleach last night with some pretty interesting results, but I want to try a different bleach to see what the difference might be.

Thanks -- Mark

 

[Ian Grant]

As a starter you could possibly use acidified Copper Sulphate and Potassium Bromide

Something like

Copper Sulphate (pentahydrate) 35g
Potassium Bromide 110g
Acetic acid (10%) 10ml
Water to 1 litre

Ian

 

[trotkiller]

Taken from page 99 of The Master Photographer's Lith Printing Course

Copper Sulphate 50 g
Sulphuric Acid 6.5 ml
Sodium Chloride 50 g
Water to 1 L

Dilute 1:9 for use

 

[Mark Fisher]

Thanks to both of you. This is exactly what I needed. I'll try it tomorrow evening!

 

[msonelson]

A reader might note that Dr. Rudman's formula calls for concentrated sulphuric acid. If you are using the 48% sulfuric acid solution double the quantity to 13ml.