Microscopic Dots on Old Black-and-White Negative

[Chris Kern]

I've been working lately with some recent scans of old black-and-white 35mm negatives made by my father during the early 1950s.  The negatives were stored for ~60 years, rolled-up, in the metal containers that the retail photofinisher used to return the film to my father.  Many are stained and contain numerous irregularly-shaped dust particles.  I had a lab rewash them for me before cutting them into fives or sixes and putting them in archival storage sleeves.  The rewashing removed some of the larger surface crud.  But many of the negatives are marred by thousands of tiny circular white dots (i.e., dark on the negative) which are surrounded by a dark (i.e., white on the negative) halo.

Anyone know what caused these?  They're much larger than the surrounding film grain and always very regularly shaped.  I've attached two samples of the same group of dots from a 1951 roll of Plus-X on acetate backing, the first a 1:1 image and the second a 4:1 image.  As a control, I checked some of my own negatives from the 1960s, which I developed myself.  None of them contained similar dots (although I saw plenty of other evidence of my own sloppy technique from that era).

[Schewe]

Could have been air bubbles on the film when the film was initially developed. White means either no exposure (unlikely) or no development. Not much to do about it now other than fix it, frame by frame.

[George Marinos]

Maybe also they are chemical particles left from an insufficient washing.

[howardm]

I'd guess insufficient initial agitation during development.

[snowrs]

Chris:

My best guess would be mold.  I shot a lot of film during the Korean 'conflict' which were subjected to a lot of humidity, and most of them ultimately looked similar to this.

Also, most of my lenses from that era ended up with mold spots on them too and ended up in the trash.

bob snow

[Steve House]

I second snowrs' guess of mold, especially if the negs were stored in a humid climate or area such a basement.

[BernardLanguillier]

Yep, it looks like mold.

May be worth checking if ICE can get rid of that at scanning?

Cheers,
Bernard

[Chris Kern]

May be worth checking if ICE can get rid of that at scanning?

Unfortunately, silver reflects infrared, so ICE and ICE-like spot-removal techniques which use that part of the spectrum don't work on black-and-white negatives.

I've resigned myself to doing as Jeff Schewe suggested in the first response to this thread: manually spotting the negatives I want to preserve frame-by-frame.  Photoshop's new "visualize spots" feature helps some, but it's still a chore.

[hjulenissen]

I've resigned myself to doing as Jeff Schewe suggested in the first response to this thread: manually spotting the negatives I want to preserve frame-by-frame.  Photoshop's new "visualize spots" feature helps some, but it's still a chore.

If these spots are really regular (highly circular, hat-with-rim profile of constant max/min values), the process may perhaps be reasonably automated using a tool of your choice. Mine would be MATLAB, but I am guessing that Photoshop gurus might be able to do something similar.

OTOH:
"if a continous circular block of pixels are all smaller than e.g. 5/256 of full brightness, assume that it is a "spot". Enlarge the area by a circumference 2 pixels wide and interpolate the entire area by surroundings".

Store the processed output and do final manual masking in something like Photoshop (to sort out cases that the algorithm did not catch).

-h