Hypo eliminator and archival processinggreenspun.com : LUSENET : B&W Photo - Printing & Finishing : One Thread
In a recent thread, Conrad Hoffman said that "Today's wisdom is that hypo eliminators are to be avoided. " I would like to hear more about this view by Conrad, how those chemicals can affect our prints and diminish their (archival ?) quality. Is there maybe someone else that has an opinion on this subject ? Since I have never stumbled on any information on this subject and never gave it any thought either, I am unaware of any minuses the use of HCA has. Isn't it supposed to do good (clear the fixing by-products off them) to the prints ?
-- George Papantoniou (firstname.lastname@example.org), February 25, 2002
Check out the following from Ryuji: http://rs.cncdsl.com/Photo-Tech/fixer.html
Essentially, HCL is good; HE is bad.
-- ricardo (email@example.com), February 25, 2002.
Yup, HE and HCA are two different things. HCA is good, but the old HE formulas may do more harm than good. For a real surprise, you can also find some studies that show trace amounts of hypo enhance archival qualities! Actually, all this may be less important then we've thought for so many years. It turns out that storage conditions (environmental factors) have as much or more to do with print life than initial processing conditions. Bad storage can negate just about any measures you take up front.
-- Conrad Hoffman (firstname.lastname@example.org), February 25, 2002.
As Conrad said, trace amount of thiosulfate is not necessarily bad, but I recommend against cutting the washing process based on this uncertain piece of information. (which, I don't think he recommended either.)
Residual fixer is not absolutely zero even after good wash processing, and the real danger is residual silver complex ions that come from intermediate step of fixing, especially with exhausted fixer. (But prolonged fixing in exhausted fixer makes it only worse -- use fresh chemical and time the fixing time carefully if you are doing quick Ilford system with fiber based papers) Fixer removers like Kodak HCA also helps wash out these complex ions.
If you want something be on the emulsion after processing to stabilize the image, use AGFA Sistan. A much better way than trace residual thiosulfate!
-- Ryuji Suzuki (email@example.com), February 25, 2002.
Thanks, Ryuji, that's exactly what I read in Anchell's book. The problem is not so great with sodium thiosulfate, but with the by- products of fixing, complex argentothiosulfates. Those are the nasty chemicals that HCA is supposed to clear our prints of, isn't it ? I have also heard of the study that resulted at the strange conclusion that small amounts of hypo are rather good for the archival quality of the print, but I don't think it is really doing something. I rather tend to believe that it is just not doing any harm. As for Sistan, doesn't it contain selenium ?
-- George Papantoniou (firstname.lastname@example.org), February 27, 2002.