Hoy os enlazo nuevamente un poco de teoría de la buena. En este caso os muestro un interesante artículo donde su autor resume el procedimiento que sigue para obtener una "copia con calidad de archivo".
Archival Processing of Prints
by Ed Buffaloe
Silver halides are the most sensitive materials available for use in photographic emulsions, but unfortunately metallic silver oxidizes very readily, so that silver images formed in our photographic negatives and prints require protection or stabilization in some way. Archival processing involves fixing film and paper adequately to remove unexposed silver halides, washing appropriately to remove excess fixer, and preferably treatment with some sort of toning or sequestering solution to prevent the emulsion silver from oxidising in the presence of various environmental pollutants. In this article, I am primarily concerned with photographic prints rather than negatives. Fixing: Adequate fixing is necessary to remove unexposed silver halides, which, if left in place, would react with light and degrade the image. Most practitioners today use Ilford’s processing method for prints, which specifies rapid fix (with ammonium thiosulfate instead of sodium thiosulfate) at “film” strength, i.e., diluted 1:3 or 1:4 instead of the old “paper” dilution of 1:7, for about one minute (compared to the 5 to 10 minutes required in a sodium thiosulfate fix)...
The ILFORD PHOTO Archival Sequence is a method of processing fiber base papers for maximum longevity while reducing the amount of water and time used.
The method, which was fully tested more than a decade ago, requires the use of a non-hardening rapid fixer mixed at film strength.
After the paper has been developed and stopped, it is placed in such a fixer for 60 seconds with intermittent agitation.
Next the paper is placed in a running wash for five minutes, followed by an immersion in ILFORD PHOTO Wash Aid (1+4) for ten minutes with intermittent agitation.
The end of the sequence requires an additional five minute running wash.
Checking Paper For Adequate Fix
It is easy to test for residual silver salts in the paper and thus check whether the paper is adequately fixed.
Make up a stock testing solution by dissolving 2g of sodium sulfide in 125ml of water. Dilute this stock solution 1+9 with water for use. Place a drop of the solution on a white area of a print that is known to be well fixed and washed. Blot any excess solution. The barely visible cream tint that remains is the reference color for a well fixed and washed print.
Soak any prints that show a yellowing of the test spot in fresh water for five minutes, then repeat the recommended fixing and washing sequence using fresh fixer.
A full, tightly capped bottle of stock testing solution will keep in good condition for three months. Once diluted to make working strength solution,