How long does sepia bleach keep?

[pstake]

I mixed up some concentrate, 100ml pot ferri and 100ml kbr to make 1L, about four months ago. It's been stored in a plastic container about half full for the past two months.

Does it oxidize beyond usefulness?

Wondering if I ought to add more kbr or even mix up a whole new batch.

 

[jim appleyard]

I can't tell you exactly how long it lasts, but it does "go bad". I tried to bleach a print with some old bleach and I noticed it took quite a while. When I mixed a new batch, it bleached the print in no time. It's pretty cheap, so you may want to go new.

 

[Mike Crawford]

Can keep for a long time though am sure will oxidise in time. I used some stock recently I probably mixed up four or five months ago, maybe more, and was fine. Sometimes, older stock will have little bits floating in it which can be filtered out, but cheap enough and less messy, to mix up fresh.

 

[Mike Crawford]

PS. I should emphasise, my comments above are for unused stock solution and not diluted and pre-used bleach which would lose it's effectiveness a lot quicker.

 

[Gerald C Koch]

Considering how infrequently you use the bleach may I suggest that in the future you do what many photographers do and make it up as you need it. One less bottle in the darkroom.

 

[pstake]

Thanks, everyone.

The bleach was still good, mixed 1:50 with water for just some subtle highlight toning. As somebody else mentioned, I don't think its capacity was as good as fresh. Times to bleach grew steadily longer.

But I tossed it all afterward and will just mix fresh from now on since I'm already doing that with the sepia.

 

[Xmas]

The KBr is stable the bleach does go off but will notice.

 

[nworth]

It does go bad. The time seems to vary, but I haven't enough experience with it to judge its real aging characteristics. You can tell by trying to bleach a spare print. When it takes an excessively long time (like twice as long as with a fresh solution) or does not bleach completely, toss it. Several months is reasonable.