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-   -   Developing Sheet Film in a Paterson Orbital Processor (http://www.film-and-darkroom-user.org.uk/forum/showthread.php?t=3926)

Trevor Crone 21st February 2011 11:14 PM

Developing Sheet Film in a Paterson Orbital Processor
 
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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 Iíve 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 Iíve 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.

Xpres 21st February 2011 11:40 PM

I like the 'domes'. Good idea which I think I'll try... thanks.:)

Neil Smith 22nd February 2011 11:22 AM

Thanks Trevor excellent article it will be useful to myself and I am sure many others, thanks very much it is appreciated.

Neil

vanannan 22nd February 2011 08:05 PM

Hi Trevor
Thanks for the interesting and helpful article, just curious as to how you control the processing temperature, I float my orbital in a large washing up bowl full of tempered water, this also makes the agitation very smooth only needing to lightly touch the sides and corners.

Trevor Crone 22nd February 2011 08:46 PM

Quote:

Originally Posted by vanannan (Post 47670)
Hi Trevor
Thanks for the interesting and helpful article, just curious as to how you control the processing temperature, I float my orbital in a large washing up bowl full of tempered water, this also makes the agitation very smooth only needing to lightly touch the sides and corners.

Hi Vanannan, that's an excellent idea. My darkroom is in the house so temperature is fairly constant at around 20C and as my development times are rarely more than 12 minutes temperature remains pretty steady.

SteveW 23rd February 2011 09:10 PM

Hi Trevor
I have a vague recollection of an article in the long gone and much missed Darkroom magazine from Ed Buziak regarding the use of the orbital. if I remember correctly he took a Dremel and roughed up the base with a grinder. I will have to try and dig it out.

Dave miller 24th February 2011 08:16 AM

Quote:

Originally Posted by SteveW (Post 47784)
Hi Trevor
I have a vague recollection of an article in the long gone and much missed Darkroom magazine from Ed Buziak regarding the use of the orbital. if I remember correctly he took a Dremel and roughed up the base with a grinder. I will have to try and dig it out.

It was an article by Roger Hicks who modified one to develop 10x8 sheet film. It was his article on which I based my own trials but ended up with a slightly different solution to the suction problem to his or Trevor's. Of them all I think Trevor's is the best simply because the modification is reversible.

Alan Clark 24th February 2011 09:35 AM

I think the question of what you do to the base of the processor is quite a complex one. I glued cocktail sticks to the base of mine (flat, not sticking up!) and this worked very well with 5 x 4 and 10 x 8 film. But when I started developing 5 x 7 film I was getting lines of overdevelopment across the negative. At first I thought these were caused by the fins then I realised they lined up with the cocktail sticks. Removing the cocktail sticks and scoring the base with a knife has cured the problem. I have no idea why these lines of overdevelopment occured, as the film had its emulsion side up.

Why should different film sizes make a difference? all I can think is that because of the curved base of the processor each size sits in a different relation to the curve of the base. 5 x 7 film sheets also have more room for side-to -side movement than the other sizes.
The main thing is that scored lines in the base, about 5mm apart, in two directions, making a diamond parrern, seems to have done the trick.

Alan

Michael 24th February 2011 11:26 PM

Back in the middle of '09 I posted pictures of a couple of removeable mats I made - see here. They do me fine, with just the occasional trace of AH left on the outer corner of the odd sheet from time to time - which washes off in a quick rinse under the tap.

So my one processor can be used for either film or paper.

Neil Smith 4th March 2011 11:41 AM

Trevor I processed in the Paterson Orbital using your method for the final tests for the Fomapan, worked a treat, processing was perfect with the fins attached. I used the self adhesive clear plastic domes you suggested on the base, brilliant.
So simple and economical it was easy using your method, thanks:)


Neil


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