Silver reflections on bw film?

[LomoSnap]

I recently discovered that a section of the film I developed, which was outside the film bag and not enclosed within it,
was emitting a shiny silver reflection. The part inside the film bag was perfectly fine.

I would like to know what caused this silver reflection.

 

[koraks]

At first glance your film looks like it may not have been fixed completely. I base this on the silvering that apparently also exists on unexposed frame edges, where no silver should remain at all after processing.
There's also the possibility of 'silver mirroring' due to environmental conditions and aging: https://www.conservation-wiki.com/wiki/PMG_Silver_Mirroring But this is more common in old samples.

 

[FredK]

Yes, Koraks has this correct! Very heavily fogged film may require longer fixing to remove all of the developed silver because the fixer, at the micro level, becomes extinguished and requires more fresh chemistry to react with all the silver. If you are collecting your silver, re-fixing should do the trick to get that additional silver from the areas.

 

[Nicholas Lindan]

Silvering of a negative can be a result of "dichroic fog." Some developer & film combinations were, and it seems still are, very prone to this problem. Dichroic fog is usually uniform, from the pictures above it looks like the silvering is proportional to silver density, and so this may not be dichroic fog as we know it.

What film, developer and agitation were used to make these negatives?

Microdol developer (without the "X") was very prone to creating dichroic fog. When Kodak changed their black and white films c. 2005 the problem seems to have gone away (and I no longer had to scour ebay for packets of discontinued Microdol-X and could use the metol/sulfite/salt DIY Microdol). The "-X" indicated a magic silver sequestering agent that mitigated dichroic fog. Somewhere on Photrio/APUG Photo Engineer/Ron Mowery revealed the X compound to be a mercaptan, thankfully an oderless one.