Deep in the instructions for the Kodak Hypo Estimator it says "This test procedure does not conform to the ANSI method of determining residual thiosulfate levels".

Likewise, on the Photographers' Formulary Residual Hypo Test it says "While the test is adequate for everyday printing, it is not sensitive enough to be used for archival printing".

I am not using Hypo Eliminator. I am using Hypo Clearing Agent.

My question is: will either or both of these tests tell me if my prints are being processed to archival standards?

-- J.L. Kennedy (jlkennedy@qnet.com), September 28, 1999

Answers

I think that if intelligently used, they can tell you if you are in the ballpark. But if the tests come out marginally, I would suggest you may not know for sure. In my own use of the residual hypo test, I get no stain at all after a 3 hour wash, and my belief is that that is as close to archival as I'm likely to get with paper. But only the methelyne blue test for residual thiosulfate can tell you precisely how much hypo is left in your emulsion. I'm betting that my great- grandson will still be able to print my negs 100 years from now, and that my photos will still be around in 200 years. But only time will tell.

-- Ed Buffaloe (edbuffaloe@unblinkingeye.com), September 29, 1999.