First of all, I have discovered (probably lots of you knew already) that a fairly complete collection of the Journal of the Society of Motion Picture Engineers (later the Society of Motion Picture and Television Engineers) and also many of the earlier "Transactions of the SMPE" are available at http://www.archive.org These are free downloads. This site has a treasure of other stuff on it including old radio programs and many technical journals. I made an interesting discovery while re-reading a paper on sea water washing "Sea Water Washing" Eaton and Crabtree (of Kodak Research Labs) JSMPE V.VXL, June 1943 p.380 et seq. The research was done because of the limitations of availability of fresh water at many military installations such as ships at sea that nonetheless had to process film and prints. In this research Eaton and Crabtree discovered that sea water washing was considerably more efficient than fresh water washing and the results permanent providing the sea water wash was followed by a short fresh water wash. It was this research that inspired the later research that resulted in the development of Kodak Hypo Clearing Agent and the discovery that sulfites were even more effective that sea water in accelerating washing. It was later discovered by T.H.James, also of Kodak Research Labs, that excessive washing resulted in a loss of image stability. This was such heresy that James was reluctant to publish his results until similar research was published by a researcher at Fuji labs. It turns out that a slight amount of thiosulfate remaining in the emulsion stabilizes the image silver. Not as well as toning with a sulfiding toner or selemium or gold toners but considerably. Now, what caught my eye in reading Eaton and Crabtree is that they _discovered the same thing_! It was not followed up but they were able to wash both film and paper prints completely free of residual thiosulfate in their tests and found on accelerated aging that the images faded much faster than when some residual thiosulfate remained. They remark only that they thought the thiosulfate reacted with the silver to produce something more stable than if the thiosulfate was completely removed. This was in 1943 and the effect was not re-discovered for something like ten or more years. About the same time as the sea water washing was being researched Crabtree, et.al. published the paper showing the result of an ammonia and peroxide hypo eliminator. This eliminator has not been recommended for general use for many years for several reasons, one being its too complete removal of thiosufate (especially if some idodide is added). This paper is also in the JSMPE. I strongly recommend this site for anyone interested in researching the history of photography especially as it was practiced in the professional motion picture industry. FWIW, the washing recommendations provided by Kodak for KHCA take into account the problem of overwashing. KHCA is now discontinued but an essentially identical product is made by Ilford.
-- Richard Knoppow Los Angeles WB6KBLdickburk@xxxxxxxxxxxxx
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