Problem of oxidation on B&W prints

I am currently in my final year at the ENS Louis Lumiere (one of two french Photography schools) and am conducting research into a process of silver oxidation, the causes of which remain unexplained. This process affects black and white prints(RC or FB) notably on warm tone papers. The silver oxidation is characterized by a yellowing and sometimes silver mirroring along the lines of contrast between high and low lighting and can appear partially or cover the whole image. It seems to depend on the storage and viewing conditions. It is surprising because of the speed at which it develops, becoming apparent in only a few weeks or a few months in some cases, and because it usually appears on prints which have been treated with the utmost care. If you have ever encountered this problem, I would be very grateful if you could answer the following questions which would help me in my research. Thank you in advance. QUESTIONNAIRE : Which paper did you use ? Make / Type : RC ou FB : Which fixer did you use ? Make / Type : Dilution : Fixing time : Number of baths : How did you wash your prints ? Kind of water ( tap, treated, filtered, …) : Characteristics of the water : Temperature ( in C ): Washing time : Did you use a wash aid ? Yes / No If yes, Dilution : Make / Type: ( He1-hyposulphite elimination- / washing accelerator / stabiliser) Did you use a washer ? Yes / No If yes, Vertical ? Yes / No Make / Type : Did you use a toner ? Yes / No Kind of toner : How did you dry your prints ? In the open air : Yes / No If yes, how : using blotting paper : Yes / No If yes, type : Did you use a cooler ? Yes / No If yes, Name / make : How did you flatten your prints ? (In the) cold (state) : Yes / No If yes, Between pasteboards : Yes / No If yes, type : ( In the) hot (state) : Yes / No If yes, Name / Make of the press : Temperature ( in C) : Kind of pasteboards : Did you exhibit your prints ? Yes / No If yes, How long did you exhibit them : Description of the place where they were exhibited Geographic situation : Time of the year : Air conditioning : Illumination : Type of frame ( wood, aluminium…) : Were the pictures framed by a professional ? If yes,could you give me his/her name, address and phone number : If no, Type of pasteboard Name / Make : Type of adhesive ( Name / Make) Adhesive tape : Yes / No Corners : Yes / No Spray glue : Yes / No Heat sealed film : Yes / No If no, what were the conditions of storage ? Length of storage : Description of the place where your prints were storage : In the dark ? Yes / No Type of storage ( plastic envelope, Permanent paper, crystal, natural pasteboard or Special archive cardboard, picture albums …) : Name / Make : Were your prints in direct contact with each other ? Yes / No Environment of the prints : Illumination ( fluorescence, tungsten, natural light…) : Room Temperature (in C) : Relative humidity : observation of the phenomenon : colouring of the oxidation : type of oxidation(partial or total, in the high lights,low density…) : How long did it take to you to become aware of the phenomenon ? Remarks :

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