"Metallic" build-up, older Tri-X Negativesgreenspun.com : LUSENET : Large format photography : One Thread
I recently pulled out some older Tri-X 4x5 negatives to reprint. I processed them in college some years ago, between 1986 and 1988. Many of the negatives are showing a spotty metallic build-up in the highlight areas; it was not noticeable when I last printed them 7-8 years ago. There does not appear to be any corresponding alteration within the shadow areas, and the mottling appears to be more prevalent in negatives that were (sometimes intentionally) overexposed. The build up has bluish cast on the emulsion side of the affected negatives, and shows as spots or blotches, especially when these areas are burned in. There is no corresponding build-up in T-Max negatives of the same vintage (perhaps due to the longer fixing times for T-max?). In those days, I did not mix my own chemistry, but was scrupulous about following recommended tank processing times. The negatives have been stored for 15-odd years in Print File archival pages, in a 3-ring binder. Some of the negatives have a bluish line about 3/4" from the bottom of the negative, opposite the slit opening in the PrintFile pages. I was wondering about 4 possible methods to remove the existing buildup or prevent any further damage: (1) Refix and rewash the negatives; (2) Experiment with Farmer's reducer (I have some duplicate negs that I would be willing to sacrifice in experiments); (3) Selenium toner; and (4) treating all of my negatives with Sistan. I would appreciate any suggestions about how to proceed. Thanks, Chris Avery.
-- Chris Avery (firstname.lastname@example.org), November 19, 2001
years ago when tmax developer first came out i was advised to use tmax instead of "tmax rs" to process my 4x5 negatives. i got a mysterious greenish metalic "stain" on all my films. it was a "dichrilic fog" (sorry if i spelled it wrong). the folks at kodak didn't know how to get rid of it, but paul crott at sprint chemistry in pawtucket rhode island told me what to do. i mixed farmers reducer (potassium ferrocyanide with his fixer dilute 2:8). i put the film in hangers, let it sit for about 15 seconds and then washed ... if they were still fogged i repeated until it was gone. this eventually got rid of it.
i am not sure if you have the same stains, or if farmers reducer will help you out. maybe others have a better idea and /or a better way to fix your film.
-- john nanian (email@example.com), November 19, 2001.
Kodak's book "Conservation of Photographs" gives a procedure for removing dichroic silver stain: a ball of absorbent cotton is dipped into a solution of ammonium hypo reducer and applied (rubbed?) in a cicular motion. This is shown in a photograph, Fig. 93. The ammonium hypo reducer is prepared by adding 15. grams of citric acid per liter to Kodak Rapid Fixer with hardner diluted to 1:3. It would be very wise to try this on an unimportant negative.
As to the likely cause, Table VIII-1 lists various stains, including "appearance of a metallic sheen of various colors. Usually bluish to brownish and often called a tarnish". The explanation is "silver stain resulting from oxidation of the silver in a non-image area" and the cause "incomplete removal of silver complexes". This doesn't quite fit your description since you see the sheen in the highlights. The appearence of dichroic silver is described as "a non-image stain yellow by transmitted light and grayish by reflected light".
After cleaning, refixing and rewashing sounds like a good idea.
You might want to buy this book or find it in a library.
-- Michael Briggs (firstname.lastname@example.org), November 20, 2001.