Pinholes on negative?

I just came back from an outdoor (subfreezing Minnesota) shoot, and processed a sheet of 4x5 (from a new box of FP4). The image has over a dozen clear pinholes. What causes these pinholes, so I can avoid doing whatever it was that caused it on this sheet?

Potential causes?
- dust from the camera bellows, (it's a 100 y.o. camera that hasn't been used lately);
- ice condensation on the film;
- some sort of chemical / pH issue (but it's boring old D-76 and Ilford hypo 1:4, with water rinse between baths);
- film coating defect;
- full moon...

Dear Robert,

Several years ago I had the same issue, and it was determined that my stop bath was too concentrated with glacial acetic acid, causing the pinholes to appear on my FP4 film. I cut the stop bath dilution to an acid volume that approximates 10ml for each litre of H2O, which eliminated my issue completely.

Are you using a stop bath after the developer?

Just curious... :)

jim k

Dust in the holders could be a problem.

Could also be caused by air bells on the film during development. What method are you using to develop?

doesn't Ilford recommend a water stop bath? Or is that Efke

Are you talking about actual pin holes or just spots on the negative? Real pin holes are pretty rare, I've never had one, but from reading about them my understanding is that they can be caused by a stop bath that's too strong or leaving film in the stop bath too long. But since you're not using a stop bath (as you should be) I'm guessing you don't really have pin holes, you have clear spots on the negative, usually caused by dust on the film.

I developed in D-76 full strength (in a 1 quart baggie), used a 30 second water stop bath/rinse, then went into Ilford rapid fixer 1:4, again in a baggie. I've used the baggie trick in the past with good results, and don't think that figures into the equation... I suspect it's dust coming off the (100+ year old) camera bellows.

I've heard these strong stop bath stories so I ran tests from plain water to 50% acetic acid without pin holes. My only experience with acid pin holes were with certain graphic arts films and those were rare.

Lynn