 BetterPhoto Member |
fiber paper yellowing I did a series of three photos and printed them on fiber paper. They are hanging in a hallway with recessed lighting and one has turned very yellow. What would be the reason for this? Did I not leave it in the fixer long enough?
|
|
|
|
||
|
Mark Feldstein |
It sounds like it could be a wash-time problem. If you reprint it, or reprint all 3, test or use fresh fixer (my own preference is Kodak Rapid Fixer) use hypo clearing agent to really cut down on your wash time, and then adequately wash and drip dry, no starch. ;>). That oughtta do it. Oh, one last thing: If you used a dry mount press, inadequately washing a print combined with high heat for press mounting, can yellow a fiber-based print too. AND..........since you seem to be one of us darkroom hands-on type people, check out the APUG.org site, sign up to support it and find incredibly accurate info about all types of photographic processes, cameras, darkroom equipment, etc., EXCEPT DIGITAL. [The Analog Photographers Users Group] It's a great haven for us film shooters.
|
|
|
|
||
|
Alan N. Marcus |
As you know, the developed image fades away unless adequately fixed and washed. The fixer’s action is complex but suffice to say: The fixer is a solvent for un-exposed and therefore un-developed salts of silver. We immerse the developed material in a fixer solution for about 5 to 10 minutes this “fixes” (renders permanent) the image. You can test the activity of the fixer: Lights on; watch a scrap piece of undeveloped black & white film as you place it in the fixer. The film goes in opaque and in just a few minutes, clears and becomes transparent. Time this operation with a watch. Double this time-to-clear, you have discovered the minimum safe fix time. After fixing comes a washing using running water. Single weight paper requires 30 minutes, double weight requires 1 hour. Washing with agitation for the above time will yield archrival standards. Use of a hypo eliminator bath reduces wash time to about 5 or 10 minutes. Immersing the material for a minute of two in a solution of ordinary table salt /sea water, followed by a fresh water wash of about 15 minutes, is just as good. Why we wash: Most papers are made of wood pulp. Wood has a cell structure that sponges up and retains chemicals. You must wash liberally to remove all traces from these cells or staining results. Modern papers are over-coated. This coat was originally a tree resin, now days it’s a polyester.. The name RC (resin coated) is retained. The RC’s purpose is to water proof the paper thus preventing the cells from sponging. RC paper has a wash time of just a few minutes. The chief ingredient in fixer is a sulfur compound. Sulfur, in time, attacks the silver based image causing it to tarnish. This is a brown-yellow stain. Stain also is caused by carryover spent developer that is oxidized. Actually the tarnish from the sulfur proved to be desirable as it converts the silver image to a silver sulfide image. This is an attractive warm brown image that is blissfully inert. Once appropriately tarnished, the image is quite stable and archrival. However, natural tarnish is often blotchy. Old time photographers resorted to intentionally pre-tarnishing using various solutions. These were collectively known as toners. Most converted silver to inert compounds some substituted other metals for the silver. All manor of browns and sepia and blue toned prints resulted Today most tones are admired for the mood they present, the archrival nature is lost to history. The answer is rub-a-dub-dub the prints in a tub. Alan Marcus
|
|
|
|
||
|
This old forum is now archived. Use improved Forum here
Report this Thread |
||