Problem developing 120 film

[LucianN]

Hy
Maybe this was posted before but i am a new user...
So, these days i was developing a B/W film in a Pentacon Triplex tank with a corex band. The method was 30 seconds agitation (rotation of spool) in the first minute and after yhat every 10 seconds of the next developing minute. After fixation and final washing i noticed some dots on the negativ film (trasparent ones) thrue the emulsion where the image is. The dots are just on the side of the negativ... sometimes clearly visble sometimes absent... on the same roll of film. Could someone explain the nature of those dots and how to get read of them? Mention: those are not air bubbles, the film beeing pre-wetted befor loading into the spool (air bubbles create black spots on negativs as i know).
Tnx for any suggestions!
Regards LucianN

[Ian Grant]

I've seen clear dots very few times in about 38 years, but there are two possible causes.

1. The tank was contaminated, maybe hadn't been washed properly and fixer has crystallised getting into the developer.

2. Far more likely - small particles of iron in the water used, these react with the fixer causing it to bleach the image, you can filter the water & solutions to prevent this.

Welcome to APUG by the way

Ian

[Trevor Crone]

Another possible cause is dust settling on the emulsion at the taking stage. These of course will print as tiny black dots.

Out of interest are there a few or many clear dots and are they really tiny or large?

Again welcome to the wonderful world of analogue.

[LucianN]

The tank was brand new (unvraped form the original box) when those spots appeared. And also after each developing the film is removed from tank and washed (stop bath in wather) afther that put back in and fixed... again out with the film for final wash... meantime the tank lays is water.... So contamination wiht fixer i gues is out of discuttion. The other hand dots are aligned in what seams to form a line... No random spots are present on the negativ... Is it possible to be caused by the corex band??? The pattern is likely... Butt i never see before such a problem to any other photographers using the same tank and corex band.
Mention: The corex band was not so tightly riped around the spool... to let the chemycals flow easely betwen the corex band and the film... others did the same and with good results...
Thanks for welcome wishes and for the answere Ian!

[LucianN]

Trevor - the dots are tiny at beginning ... groving to a point and after that decreasing again. The dots are trasparecies in the negativs at the margin of the image. So dust is not the cause of that.
Thank you for welcoming me... really a wonderfull world

[Ian Grant]

If it's only one film perhaps it's a coating fault.

Ian

[LucianN]

no.... multiple films same problem

[Ian Grant]

What make of film ?

Ian

[LucianN]

The film is Fomapan 100 ISO, but also developed T-Max 35mm with smaller amount of dots... I dought T-max is low quality on emulsion:| Could it be a mechanical problem.... corex band scratching slowly the emulsion on the film while i am agitating the spoll... ??? Still never see this kind of troubles before.

[Bob F.]

Can you post a scan of the offending negatives?

Cheers, Bob.