Keeping properties of bleach?

winger · Apr 12, 2016

I've been itching to try some bleaching processes (second pass lith and bleaching out a print after drawing on it). I have the potassium bromide and potassium ferricyanide to make some from scratch. Once those are mixed with water to make a stock solution (there's a recipe in Christina Z. Anderson's book - The Experimental Photography Workbook), how long will it keep? Is it measured in hours, weeks, months, or more? I just know I may only have a chance to use some occasionally, so I wouldn't want to make a lot and have it be bad by the next time I want to use it. I intend to keep it and fixer separate.

Rich Ullsmith · Apr 12, 2016

Okay. I mix the KBr and Kferri into a stock solution of 100g+100g+1L water, and I draw off that for a couple years. I cannot recall ever the bleach going "bad."

Rich Ullsmith · Apr 12, 2016

Ah, sorry, unless you are doing multiple bleaching processes, then the bleach gets contaminated. Then I would dispose of it. If the bleach is seeing an archivally washed print, it works good and lasts long time.

Alan Johnson · Apr 13, 2016

I have a sealed bottle, used on multiple occasions, that is several years old and still works.
Keep the ferricyanide solution out of contact with air when not in use.

Doremus Scudder · Apr 13, 2016

Rich Ullsmith said:
Okay. I mix the KBr and Kferri into a stock solution of 100g+100g+1L water, and I draw off that for a couple years. I cannot recall ever the bleach going "bad."

This is what I do as well. Use good-quality bottles and the stock solutions should last a couple of years at least. Working solution goes bad easily when contaminated. Any trace of fixer will degrade the bleach very quickly. I just make up what I need for a session and then discard it afterward.

Doremus

bdial · Apr 13, 2016

I have a bottle of dilute sepia bleach that I mixed at least two years ago that is still working well, used a little of it yesterday to brighten some highlights. It's stored in a plastic juice bottle (relabeled).

winger · Apr 13, 2016

Cool! Thanks very much everyone - very good to know. And yes, I was planning on taking some from a stock bottle each time and discarding that after use. It was the keeping of the stock bottle I was curious about because I figured I'd make less of it if it was going to go bad soon.
Thank you all!

Gerald C Koch · Apr 13, 2016

I know how much APUGers seem to like making concentrates. Potassium ferricyanide is safe to use however if there has been any degradation there may be a problem. As a matter of caution potassium ferricyanide and its solutions are effected by light, heat and even age. Read the MSDS below.

Many photographers who use it for say bleaching prints just make it up by eye. That is to a certain yellow color. The darker the yellow the faster the bleaching. The used bleach solution should be discarded safely. Flush the sink afterwards. Avoid contact with acid solutions. Again its safe to use but be aware of the warnings. Any discolored solutions should not be used as they can cause staining of films and prints.

I include the MSDS which should be read for ALL chemicals before they are used.

http://www.sciencelab.com/msds.php?msdsId=9927405

bdial · Apr 13, 2016

Appreciate the warning Gerald; mine, FWIW, is a nice light yellow color.

winger · Apr 13, 2016

Gerald C Koch said:
I know how much APUGers seem to like making concentrates. Potassium ferricyanide is safe to use however if there has been any degradation there may be a problem. As a matter of caution potassium ferricyanide and its solutions are effected by light, heat and even age. Read the MSDS below.

Many photographers who use it for say bleaching prints just make it up by eye. That is to a certain yellow color. The darker the yellow the faster the bleaching. The used bleach solution should be discarded safely. Flush the sink afterwards. Avoid contact with acid solutions. Again its safe to use but be aware of the warnings. Any discolored solutions should not be used as they can cause staining of films and prints.

I include the MSDS which should be read for ALL chemicals before they are used.

http://www.sciencelab.com/msds.php?msdsId=9927405

I agree with the safety warnings (well versed in MSDS here). But as a forensic chemist (retired) I just have problems making up something to a "certain color." My first inclination is to ask what I'd get on a colorimeter or a spectrophotometer. Especially since I've never seen the "certain yellow color" in person. I know, I know, but my analytical side has to win occasionally over the artsy, bucket-chemistry side. So I do plan on mixing the stock solution as noted by Rich Ullsmith.

Gerald C Koch · Apr 13, 2016

winger said:
I agree with the safety warnings (well versed in MSDS here). But as a forensic chemist (retired) I just have problems making up something to a "certain color." My first inclination is to ask what I'd get on a colorimeter or a spectrophotometer. Especially since I've never seen the "certain yellow color" in person. I know, I know, but my analytical side has to win occasionally over the artsy, bucket-chemistry side. So I do plan on mixing the stock solution as noted by Rich Ullsmith.

My comment about mixing to a certain color was restricted to bleaching prints. The exact concentration of ferricyanide is not that important that you need weight it out. Old time photographers would just reach for the solid potassium ferricyanide and use enough based on color to bleach at the rate expected based on experience.

I doubt that Edward Weston ever owned a balance. The portrait photographer G Paul Bishop when making up his developer eyeballs the amount ingredients. There are times when you can cut corners and times when you can't.

Keeping properties of bleach?

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