Clear spots in Tri-x Emulsion

[brian steinberger]

I just processed a roll of 120 Tri-x 400 in D-76. The roll was mostly clouds and sky. I hung the roll up to dry and noticed tiny clear spots in a few of the images. It looks like the emulsion is simply missing. They are so tiny, but would still result in tiny black specks in the print. There are no more than 2 or 3 on about 3 or 4 of all the photos, that I can notice. I bought the film USA from B&H, so it should be good. I'm just wondering if anyone has ever had this problem, or knows what this is. Thanks

[Frank Petronio]

usually it is dirt

[Craig Wactor]

yep, dust in the camera/film holder.

[Donald Qualls]

Conceivably, could also be due to bubbles in the developer that persisted through 80-90% of the process time. Typically, however, bubbles will be bigger than dust, and often have the characteristic bell shape (they were called "air bells" when I learned to develop film, 35 years or so ago, because of this).

Dust is a lot more likely, and is mainly a problem with removable backs or folding cameras, though it can also infest respooled film (for use in a 620 camera or rollfilm adapter).

[Terence Spross]

Tiny air bubbles can take that form if you rap the film (or tank) as you first put it in the developer as that gets rid of the larger air bubbles brought in as the film entered the liquid. But tiny air bubbles remain sometimes seeded by tiny dust particles chenical reaction and that remains when you don't agitate enough. By the time the film gets to the fixer those air bubbles are gone from the the stop bath and the action of re-imertion into the fixer and the silver gets fixed so the spots are clear.

So, try agitation more vigorously especially at the start of development. Also even bigger air bubbles won't be bell shaped if the film is horizontal in a tray process instead of a tank process. (When I do sheet film I use a tray process myself.) I realize that you probably don't do 120 film in a tray although I know someone who used to (long narrow trays).

I recommend using a fine (horsehair) brush on the film if its been respooled and/or brush it just after taking it off the backing paper and before putting it in the tank.

[John Cook]

Just to cover all the bases and mention every conceivable cause, here’s one more:

Tiny airborne crystals of hypo can land on wet film and completely eat away the emulsion.

Not a good idea to mix powdered hypo near where film or prints are dried. Always wipe up fixer spills before they dry.

Cleanliness is, indeed, next to Godliness.

[Brian C. Miller]

Since its roll film, I'll go along with the air bubbles. After every agitation cycle, bang the canister on the countertop. That will dislodge any air bubbles.