Airbells pinholes & white spots

[Gary Holliday]

I've had recurring problems with negatives and need some help identifying the culprit.

I can't post a picture so will do my best to describe the problem.

The emulsion has small "pinholes/ airbells" at random parts of the negative.They are usually light grey with a black ring around the edge and are approx 1mm diameter.

Efke 50 120 and possible other films.
Paterson Small tank
Rodinal 1+50
Water stop
Iford rapid fixer 1+4 for 5 mins max
2 inversions every 30s for the processes with continuous agitation at the start of each process.
Sometimes I tap the tank on a hard surface.
20 min wash in flowing tap water.

I don't pre-soak, but may try this.
I've cleaned out the film back.

The black rings are the interesting part, so does this suggest a problem at the developing stage?

 

[glbeas]

Have you noticed any particulates floating in your water and/or developer? If the developer has any chemicals precipitated out that sticks to the film it might cause what you are describing. Otherwise it sounds like an emulsion defect.

 

[Photo Engineer]

Airbells and pinholes are generally clear small spots on the negative with no ring and no darkening. I think Gary has hit it. Undissolved material will cause dark rings and dark dots.

PE

 

[Gary Holliday]

So oxidised Rodinal?

 

[Photo Engineer]

Undissolved chemical specs or something in the water?

PE

 

[Gary Holliday]

I've used two different locations for the water supply so I can rule that out. My agitation technique is good and I always use pre-prepared liquid chemicals.

My recently processed Acros looked good, so I'll hunt out the other negatives and see if it was a dodgy brick of Efke.