Shanghai GP3

Thanks scrambler for the tests. My presoak was about a minute with agitation in the middle of that, not very long at all, no second rinse, just presoak then dev.

Perhaps take note of the emulsion number perhaps for any bad rolls (they're below the expiry date).

I might roll up some of the backing paper with some scrap film and put it into developer together and see if it reacts and does something to the film.
I was deliberately OTT with the prewash for the first one, and accidentally for the third 🙂
 
Two unexposed rolls, one 5/2015, one 8/2015. No pre-soak (as it didn't seem to make a difference above)

No marks on either.

I may just not be turning up the random affected examples, but at least it shows that it's not simply a batch issue (i.e. some batches consistently have problems and some don't.)

What options are left?

It might be something to do with pressure plates and tension in the cameras? Though last test I had one really bad and one good from the same camera.

It requires exposed film? - but the marks showed very clearly on unexposed portions of the affected films which is why I tried the unexposed film.

4 of my last 5 developed rolls (admitted two unexposed) have been fine. This is the best run I've had with this purchase of GP3!
 
Next test: the last for today.

I checked the manufacturer website which states that the film needs to be stored at <21 degrees C and <65% humidity. In a sealed foil pouch I imagine the humidity element can be taken for granted ... but then some of the pouches have a nick for easier opening which could possibly make the pouch not moisture tight.

Choosing an unmarked pouch, I placed the film, still sealed, into a container of 45degree C/ 114 degree F water for 30 minutes and then developed with a 2 minute wash (just because it's satisfying seeing that blue rinse come out!)

Again, no marks.

I suppose next I should try moisture.

It's hard to work out how to avoid trouble if you can't provoke it, but it happens sometimes anyway!
 
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