Shelf life of fixer

[Petzi]

What is limiting the shelf life of fixer, especially the common liquid rapid fixer concentrate? What happens to fixer when it "expires"?

 

[Gerald Koch]

Usually when fixer starts to go bad it throws down a precipitate of sulfur. The solution will begin to turn milky and eventually yellow crystals of sulfur can be seen in the solution. However, ammonium thiosulfate fixer to which the hardener has not been added seems to have a long life.

 

[Photo Engineer]

Acidic fixers (pH lower than ~6) keep less well on the shelf than those above pH 6. Some fixers last for a shorter period of time even at the same pH. One brand of fixer lasted less than a year on the shelf sitting next to some Kodak fixer that made up to the same pH and was still ok.

PE