How does Hypo Clearing Agent Work? What's the Chemistry?

[MattKing]

If the fixer has no hypo in it, eg. Ilford Rapid Fixer, is there any point to using HCA?

Whether your fixer is a "standard" fixer using sodium thiosulfate (formerly known as sodium hyposulfate) or a "rapid" fixer using ammonium thiosulfate (which I guess in days of yore might have been called ammonium hyposulfate) is immaterial when it comes to the question - HCA will do the same job.

 

[markbau]

Of course one of the advantages of getting older is that the older you get the less you have to worry about archival business. On the last day I ever print I'm not even going to use HCA for my fibre prints, why would I?

 

[john_s]

Of course one of the advantages of getting older is that the older you get the less you have to worry about archival business. On the last day I ever print I'm not even going to use HCA for my fibre prints, why would I?

Will nobody ever want to see any of your prints after you're gone? I treasure an original print of my great grandparents taken in 1889, sepia toned, Taken at Violet Town (not so far from where you are at Woodend).

 

[darkroommike]

I have always been of the opinion that the liquid washing aids with the really, really, really short treatment times and the subsequent really, really, really short washing times were mostly photographic snake oil. Even KHCA's published instructions are in my opinion, overly optimistic. It pays to take all such claims with a grain of salt (or sulfite). You can only get the results you need after performing some simple tests. David Vestal's book, The Art of Black and White Enlarging, outlines some good procedures on testing all such claims. I can also recommend Dr. Richard Henry's book, Controls in Black and White Photography, for the real poop.