Air Bells

Appearance

If air bells occur during development, it shows as a small transparent spot. Sometimes a minute, dark streak leads from the spot. When the negative is rocked in a tray, the streak projects from each side of the transparent spot in the direction the tray is rocked. If the tray is rocked in two directions, the streak will form a cross with the transparent spot in the center. When air bells occur in tank development, the dark streak usually forms at the lower edge of the transparent spot. When air bells occur in the fixing bath, they show as small, round, dark areas.

Cause

The transparent spots that occur in the developer are caused by air bubbles on the emulsion surface, which prevent the developer from contact­ing the emulsion. The darkened streaks result from excess oxidation of the developer caused by the air in the bubbles. The dark spots that occur in the fixing bath are caused by a pocket of air holding the fixing bath away from the emulsion and allowing a slight continuation of development.

Remedy

Immerse film carefully and thoroughly in the developing and fix­ing solutions; move film during development and fixation in order to break up and prevent air bells. Water always contains some air and, when the tempera­ture rises, this air is expelled. It forms small bubbles on the inside of the tank and also adheres to the film surface during the preliminary stages of development.

Using a Tank (Patterson, Jobo)

If you use Photo-Flo or any similar product in the tank for the final rinse step (as some of us who follow the Ilford archival sequence do), be sure to rinse the tank and reels thoroughly after each session. Any residual surfactant when rewetted, especially in combination with certain developers, can produce foaming and bubble

Pre-Wash/Soak/Wetting the film seems to help a lot of people as well

If you use the Inversion technique you can try to bang the tank on the table once done. Seemingly this is will destroy the air bubbles