uneven development

[numnutz]

Hi - For the last forty or so 5 x 4 inch exposures I have been using a Paterson Orbital tank (motorised) with Retro Pyro, developing for approximately 7 minutes depending on temperature. I have noticed on a few negatives, 4 or 5 out of the forty signs of uneven development in sky areas.

On the example attached the streaking is in the sky. It seems to be in a similar place on each example, but I don't keep a record of where in the tank an individual bit of film sits.

The film I normally use is HP5+ although the example attached is noticeably the worst so far and happens to be Rollie Infra Red.

Can anyone suggest a cause and / or cure?

nn

 

[Ian Grant]

Maybe there's insufficient developer ?

Try and get a Jobo tank, I have a couple of 2000 series that both take two sets of spirals 6 sheets/spiral so 12 per tank, much easier to use. Later Jobo's are available as well,

Ian

 

[Trevor Crone]

I do use my Orbital for the occasional processing of 4x5 using PMK pyro and so far negs. are very evenly developed. I use 150ml of dev. and I rotate the the Orbital manually (I don't have the motor). Use it manually with a couple of test negatives exposed to large amounts of sky area and see if there's an improvement.

My main dev. tank for 4x5 is the Combi Plan which I find very consistant in use. However as mentioned I do use the Orital when processing less then 4 negatives as it's very economical with chemistry.

 

[Jim Noel]

I am not familiar with the Orbital. Does it reverse directions, or does it always spin in one?
It needs to reverse to help eliminate streaking.
Sometimes the efforts to save on chemistry by using the minimum that will cover the film does not provide enough developing agent to do the job over the total area of the film.