Developing Sheet Film in a Paterson Orbital Processor
I use a Paterson Orbital for processing 5x7 and 8x10 film and if I only need to process one or two sheets of 4x5. I have two processors, one with the fins still in place and one where I’ve removed them and all I can say is film processed in either are identical, very evenly developed. However some folk have found the fins to be the cause of odd processing marks so it may be prudent to remove them. To date I’ve only used two developers with the Orbital, Rodinal and PMK pyro. My agitation plan is identical with both developers. I keep the processor flat, no manual base is used, I just tilt it gently L to R and corner to corner. I do this sequence about every 2-3 seconds throughout the development, that is tilt to the L, leave tank level for 2-3 seconds then tilt to the R and again leave tank still for another 2-3 seconds. I then tilt it to one of the corners then the opposite corner. When all four corners have had their tilt I revert back to L-R and so on. I use 250ml of working solution to be certain the film is evenly covered because my agitation is fairly gentle. Too vigorous agitation can give an increase to edge density - developer bouncing too much off the sides of the tank. The only time I've had problems is when I initially used the motorised base - this caused under development to the centre of the film. I always pre-soak the film in 600ml of filtered tap water for 2-3 minutes with occasional agitation before starting development..
Make sure you also keep the tank scrupulously clean. I always wash and dry mine after use.
A test I did some time ago was to place a dead sheet of 8x10 film in the tank without the lid and covered it with 250ml of water to see how the film physically responded to various methods of agitation, the tank needs very little movement to create an effective yet gentle flow paten and not once did the film float to the surface of the water.
Because the base of the tank is smooth it needs some form of modification so the film is fixed and washed properly and is clear of dye and anti-halation layer. Many folk have scored fine grooves in the base of their tanks which works fine, however on my tank I have stuck small self-adhesive clear plastic domes (see photograph) available from art supplies and not one has come unstuck or decolourised after over two years of use.
Please note these are my working methods which work well for me, they may not suit you but hopefully will provide a starting point to attaining your own level of complete satisfaction.
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"To the attentive eye, each moment of the year has its own beauty, and in the same field, it beholds, every hour, a picture which was never seen before, and which will never be seen again" Ralph Waldo Emerson.
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