Brown fixer?

[domenico Foschi]

Well, this is what happened:
Today was sepia toning day of some Ilford Warmtone 16 x 20's .
The tray are as follow. Presoak, Bleach, Sepia, Fixer, and H2O.
When I print in neutral tone paper I do not use fixer, but with warmtone paper I do in order to stop the toning action which otherwise would go on even in a tray of water.
I normally put a tray of water between the bleach and the sepia and the sepia and the fix to prevent untimely exhaustion, but not this time for lack of space and bcause I didn't have many prints anyway.
Today, as soon as I put the first print in the fixer, a dark brown precipitate formed, seeming to come from the shadows that I very rarely tone, not this time anyway.
This gunk tends to stick and stain the paper, especially in the unexposed borders
The toner I use is always the same: the Kodak sepia toner in the bags, the old formula,The fixer is the Arista no hardener.
Hoping there is somebody knowledgeable of the causes of this accident ....
Thank you in advance.

[Michael Gudzinowicz]

There are a couple of probable causes. If the fixer has been used, it may contain a significant amount of complexed silver which will react with sulfide ions to form an insoluble silver sulfide precipitate. Likewise, if fresh fixer were used, it may solubulize bleached silver ions that have not reacted with sulfide permitting the formation of a precipitate if sulfide is carried over.

I'd bleach a scrap print, and tear it into sections. Tone one as you did, without washing, to see if the problem is reproducible. Wash the reamining scraps after bleaching, and tone in sulfide. Wash one after toning before transfering to fixer, and transfer another from toner to fixer directly. You could also add a few drops of sulfide toner to 1 ml or so of fixer to determine
if silver in the fixer reacts directly with the sulfide toner. If a short water rinse (15-30 sec) doesn't remove the toner prior to fixing, substituting hypoclear for the water may hasten the dilution of sulfide.

Anyway, if that approach doesn't sort out the problem, repost, and you might want to drop a note to Tim Rudman.

Mike.

[domenico Foschi]

Thank you Michael,
The fixer I used today had been used yesterday for printing.
I believe this is the cause of the mishap, but at any rate at next toning session I will do as you suggest and let you know.
Thank you.