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Old 18th July 2009, 04:19 PM
Michael Michael is offline
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Default Paterson Orbital processor revisited

I want to return to this subject, as I managed to get a Paterson Orbital processor on eBay last week. As I'm not keen on modifying things unless it's quite necessary, I re-invented the wheel yesterday and processed four sheets in it as bought.

Brief details: Delta 100 exposed at 100, developed 5'6" in Ilfotec HC 1+31 at 20C. I used 150 ml for developing, stopping and fixing and 200 ml for pre-soak and washes.

Narrative: There's no motor (R. Hicks argues against them, by the way); so I gave more or less continuous manual agitation right through. I washed (several changes, each double the length of the last) but didn't give a wetting agent rinse without inspection. That made sense, as there was still anti-halation coating when I opened the Paterson; so I transferred the sheets into my Doran tank and gave several more rinses. When the sheets were clear, I gave them a wetting agent bath and then hung them up to dry overnight. This morning, there was a tiny residue of anti-halation coating on the "drip corner" of one of the sheets. Apart from that (and it was on the rebate only), the sheets seem to me to be better processed than I have ever managed with the Doran (3 years' experience with LF processing).

Experiment: My next plan is to make a removable insert for the processor, to see whether it is feasible still to use it unmodified by drilling or resin bumps. In a cook shop on Thursday I found a "Silicone baking mat" (you can Google that expression), thin, flexible and, I hope, chemically inert. I plan to cut it to shape, punch holes in it for the pegs and try it out. It is quite smooth on one side and should adhere to the processor base in the way that film does: the other side has a small, regular bubble pattern, which should allow fluids to reach under the film.

Note: I've never given Delta 100 a pre-soak before; and I've never noticed the spent developer discoloured by anti-halation coating. CHS 50 is quite different in that respect. If the silicone mat works, then I hope that it will help the pre-soak. If it doesn't, then transferring to a deeper tank as I did is not a huge bind and I might just carry on that way. I'll be using Adox APH09 for CHS 50, the stronger dilute.

If you've read this far, thank you! Comments welcome, polemical or encouraging.
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Old 18th July 2009, 05:00 PM
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Trevor Crone Trevor Crone is offline
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Michael, the modification you mention sounds a good idea. FWIW I also use an Orbital processor mainly for 8x10 film but occasionally for 4x5, particularly if I only need to process a couple of sheets. I modified mine by sticking small self adhesive plastic domes available from art shops to the base (see attached picture). These have never come unstuck despite being exposed to chemicals and water.
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Old 18th July 2009, 06:57 PM
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Trevor - Thank you for that information. Oddly enough, we have packs of those bought as "clear door buffers" in a Lisburn hardware shop (our house is new and we're still faffing around with wee jobs like that). I'd much prefer your method to an irreversible one.

A little progress in my experiment: I have successfully cut out a piece of mat the right size, holed it using a piece of paper as a template and fitted it. The mat is 1.4mm thick. I have also subjected a piece of scrap to heavy doses of developer, stop and fixer with no apparent ill effects (either to the silicone or to the chemicals). So far so good. If it stops raining here, I'll expose and process more film tomorrow. At least the cricket detracted from the misery of the day - or added to it, if you don't like cricket.
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Old 20th July 2009, 08:34 PM
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Further progress: the mat works fine. What came out of the tank after a 200 ml, 4 minute agitated pre-soak was very colourful indeed. At the end of everything, the negatives were clear and even and still in place but not stuck: they are now drying.

Now I need to investigate light leaks at the negative corners. However carefully I seat the holders, I still get them from time to time.

Trevor (and Dave, for the original impetus and advice along the way), thank you very much. This makes 5x4 processing a lot easier. My only slight concern is friction and possible resultant wear between tank and base while agitating. I might try the Lewis Carroll solution for that.
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Old 21st July 2009, 07:17 AM
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Michael, pleased to read things are going well with your processing of sheet film.

With regard to friction of film base, using the self adhesive plastic domes as I've mentioned, doesn't in any way mark the film.

Light leaks, this could be the result of a number of causes, i.e. poor seating of the film holders in the camera back. I've also had slight fogging of the film corners when I used a too bright a room light above my Orbital processor, came through the pouring slot. So one corner was always slightly fogged. I simply cured this by using another light some distance from the processor.
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Old 21st July 2009, 01:15 PM
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Trevor - Your method has to be superior to mine on one major count; but I have a question for you.

Firstly, on inspecting my *dried* negatives, I notice small (but disastrous) marks from contact with the flow control vanes in the tank - or else from to strong a flow governed by those vanes. It's not quite clear which. That means to me that my mat is too thick overall, leaving too little room for the film to move. Back to square one.

Now, the question for you: your illustration shows a tank lid without those vanes. Has the lid been modified or did it never have them?

[Don't worry about my light leak business - it's a separate issue which I'm going to ask about in a separate thread].

Last edited by Michael; 21st July 2009 at 01:17 PM. Reason: underlining "dried" didn't work
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Old 21st July 2009, 01:26 PM
Dave miller Dave miller is offline
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Quote:
Originally Posted by Michael View Post
Trevor - Your method has to be superior to mine on one major count; but I have a question for you.

Firstly, on inspecting my *dried* negatives, I notice small (but disastrous) marks from contact with the flow control vanes in the tank - or else from to strong a flow governed by those vanes. It's not quite clear which. That means to me that my mat is too thick overall, leaving too little room for the film to move. Back to square one.

Now, the question for you: your illustration shows a tank lid without those vanes. Has the lid been modified or did it never have them?

[Don't worry about my light leak business - it's a separate issue which I'm going to ask about in a separate thread].
How thick is the matting that you've used?
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Old 21st July 2009, 02:06 PM
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1.4mm, Dave (I had buried that information in an earlier post). Its uniform thickness may go against it.
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Old 21st July 2009, 02:33 PM
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Michael, I removed the vanes from my processor for fear they would cause developer flow patterns. Although I have recently bought a second processor (so I can use one away from home) and have left the vanes in place and have not noticed any marks whatsoever from them. Perhaps the mat you are using is placing the film surface too close to these vanes?
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Old 21st July 2009, 03:02 PM
Dave miller Dave miller is offline
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Quote:
Originally Posted by Michael View Post
1.4mm, Dave (I had buried that information in an earlier post). Its uniform thickness may go against it.
There isn't much room between the vanes and the base. If you press a little modelling clay to one and then press the lid in place you will see just how little. I suspect your mat thickness is the problem. I haven't taken the vanes off any of mine, and it's not a problem I have ever experienced.
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