BW negative developement problem (lot of transparent spots)

[penauts]

Hi, I just started developing my own negatives at home.
Unluckily it happens that at the end of developing process I find on the negative a lot of small points where the emulsion is full transparent.
I attach a photo of the 4x5 negative for reference scale plus a detail.


I developed 20+ negatives and on every negative there are those little spots, sometimes less sometimes more.

This is how I develop films:
1-immersion in water 10 mins
2-I put film in developer and do the developement with agitations and stuff
3-I put the film in ilfostop for 30 secs
4-I put the film in ilford rapid fixer for 10 min
5-i wash the film for 10 mins
6-i wash film with wetting agent
7-i let the film dry.

-I mixed my chemicals with demineralized water
-I tried different films (both fresh and expired ones)
-I used two different developers (ID11 and perceptol, both stock solutions)

I tried using an ortho film, and I realized that the points are present after the first phase (developing), but I have no idea why they form.

Has anyone encountered the same problem and know how to fix it?
Thank you in advance!

[Tobias Key]

Could be dust. How are you loading your film?

[Jac@stafford.net]

I see white spots in the detail image. Is that what you mean?

[penauts]

I tried to blow air with a compressed air can to the negative (before shooting the photo) with no visible difference in the results

And yes, the white spots are what I mean. I didn't call them "white" because in fact they're transparent. For the photo detail I put the negative toward a light source.

[Jac@stafford.net]

My modest experience tells me the spots are too regular to be dust. My best guess is they are pinholes caused by the stop bath being too strong so that it makes little bubbles through the emulsion; they pop, expel gas and take bits of the emulsion off the film.

Best of luck, and thanks for the puzzle.

[penauts]

I used Ilford line film (not dated, I think that it's from the late '90) and Ilford FP4+ brand new (exp april 2018)

Thanx for the suggestion, I can try diluiting the stop bath (even if I mixed it following Ilford's instructions) and see if it goes better

[paulbarden]

TEN MINUTES in Rapid Fix? Seriously?

[penauts]

Yes, I read somewhere that those spots could be caused by incomplete fixing (?) so I doubled fixing times hoping for the better
but that didn't work

[Jim Noel]

These could be air bells. Agitate vigorously for the 1st 30 seconds in developer.
Switch to pure water for a stop bath. This eliminates the possibility of problems with difference in temperatures.

[penauts]

ok, I'll try those suggestions, thank you very much!