Invisible Marks on Negatives

[jurgenestanislao]

I discovered something earlier while cleaning up after a platinum printing session.

I usually fire up my UV box just to check it before I put it away, while doing so in the dark, ambient UV from the box hit a few 8x10 negatives on a table nearby then I noticed something odd, all my negatives had weird markings.

And so I decided to place some of these negatives on inside my UV box and lo and behold—they all have the same marks (see attached) only visible under UV light. These markings are neither visible with the naked eye nor do they show up in scans.

This explains a test print I did a month ago that displayed some odd blotches (see attached) which I just shrugged off.

Any ideas what these might be?https://uploads.tapatalk-cdn.com/20200915/6036abff44bcd82e1aa855e0e489842c.jpghttps://uploads.tapatalk-cdn.com/20200915/973f1b51f310033d0e2c33b9ecbc46fa.jpg

Sent from my Pixel 4 XL using Tapatalk

[Vaughn]

Perhaps the anti-halation layer did not completely wash off...and it might have some UV blocking ability.

How are you developing your negatives?

[NER]

Based on the uniformity of the pattern and my astonishing ignorance of photography, I suggest these might be markings imprinted by machinery (e.g., cylinders, casting wheels, rollers, etc.) used in the manufacture of some component of the film. It does not appear to be a coating problem and, with all due respect to Vaughn, I suspect the pattern would not be so uniform if it were caused by incompletely removed anti-halation material.

N. Riley
http://normanrileyphotography.com

[Vaughn]

How do you develop your film?