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  #11  
Old 21st July 2009, 04:31 PM
Paul Owen Paul Owen is offline
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I've recently switched to a Paterson Orbital after moving up to 5x7 from 5x4 as its the ideal way of processing 2 sheets of this bigger format.

I have made a few modifications to mine and have seen improved/more consistent results. I have discussed these in detail on my blog but very briefly these involved removing the fins, changing the pegs and altering the surface of the base with some "bumps"!
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  #12  
Old 21st July 2009, 05:56 PM
Dave miller Dave miller is offline
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Quote:
Originally Posted by Paul Owen View Post
I've recently switched to a Paterson Orbital after moving up to 5x7 from 5x4 as its the ideal way of processing 2 sheets of this bigger format.

I have made a few modifications to mine and have seen improved/more consistent results. I have discussed these in detail on my blog but very briefly these involved removing the fins, changing the pegs and altering the surface of the base with some "bumps"!
I’ve read you blog comments with interest Paul, but feel that I should point out that the fins were never intended to hold the paper, since that would have caused processing marks, their purpose is to spread the small amount of fluid that the processor was designed to use evenly across the base, especially to the middle. As the volume of fluid used is increased, their usefulness decreases, however I have never seen any bromide drag marks from them, only from the pegs. In my view there is no point in removing them.
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  #13  
Old 21st July 2009, 06:24 PM
Paul Owen Paul Owen is offline
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Interesting point Dave. I removed them simply because I was getting uneven development- however, I've come across people who've never had this problem - must be me
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  #14  
Old 21st July 2009, 06:28 PM
Michael Michael is online now
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Yes, I'm sure you're both right. I think I'll stick on those wee plastic domes.
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  #15  
Old 21st July 2009, 06:29 PM
Dave miller Dave miller is offline
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SNIP must be me
If only it were that simple.

It never ceases to amaze me that one person will get good results with a working method, or material that totally defeats another.
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  #16  
Old 21st July 2009, 06:30 PM
Dave miller Dave miller is offline
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Yes, I'm sure you're both right. I think I'll stick on those wee plastic domes.
They do seem to be a much neater solution than my epoxy glue splattering.
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  #17  
Old 22nd July 2009, 10:51 AM
Michael Michael is online now
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Last night I developed 4 sheets of CHS 50 (APH09, 4.5 ml in 180 as I'd read that 1 5x4 sheet needs 1 ml of concentrate, 9 minutes of continuous agitation but gently). Before totally discarding my mat, I decided to cut away any part of it directly under the vanes. Ended up basically with a cross shape, each arm held down by a peg. That actually has worked pretty well: the pre-soak was extremely colourful, the film didn't stay sucked on to the tank base and development was as even as I could wish (I'm really going to take to CHS 50 and don't mind the non-availability of Pan F+ at all now).

I scanned the negatives this morning: the images aren't great but I'll make blueprints of a couple.

Thank you, everyone for the moral support in this thread. I'm going to persist with the cut down mat for a little longer, keeping the Crone hemispheres (nice anatomical-looking term, that) up my sleeve in reserve.

Last edited by Michael; 22nd July 2009 at 10:52 AM. Reason: APH09 for AP09
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  #18  
Old 22nd July 2009, 12:15 PM
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Trevor Crone Trevor Crone is offline
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BIG SNIP;..........keeping the Crone hemispheres (nice anatomical-looking term, that) up my sleeve in reserve.
I really must go on a diet. There's no way my hemishperes would fit up your sleeve Michael
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  #19  
Old 25th July 2009, 08:59 AM
Dave miller Dave miller is offline
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I was using my Patterson unit yesterday and found myself thinking about this thread, particularly the subject of what the two vanes are for, and whether they serve any useful purpose with regard to film development.
When a sheet of 10 x 8 r/c paper is placed in the unit it is obvious that they are not there for the purpose of holding that it in place, since the curve of the base does that. They may come into play when two, or four small sheets are developed.

What was obvious, when using the unit with the lid off, and the unit on the motorbase, was that the small amount of fluid recommended for paper development does not reach the centre, but rather chases around the edge under the action of rotation. If the amount of fluid is increased to about a 100ml then it starts to spread to the centre, but the majority of the flow is still at the edge. It is not until the fluid is increased to about 150ml that I would judge the fluid level in the centre to be adequate. However the majority of the turbulent flow is still around the tray edge. So, it is obvious to me that the primary purpose of the vanes is to direct some of the fluid across the centre of the medium and even out the flow rate.
Without the vanes I would be concerned about the higher level of developer activity towards the perimeter of the tray. None of this applies if the tray is hand-held and agitated in a random fashion, or filled to the extent that the whole base is covered with the unit at rest, about 350ml is necessary to achieve this later state.
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  #20  
Old 25th July 2009, 12:17 PM
Paul Owen Paul Owen is offline
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I think herein lies the problem ... if you increase the amount of chemistry in the processor to between 180 and 200ml then the film does float and does come into contact with the fins. I have a number of negatives clearly showing banding that corresponds to the position of the fins; if you reduce the amount of fluid then the film is less likely to float - but with the "bumps" installed there is still a chance as chemistry is under the film.

However, I think Dave has hit the nail on the head ...

I, for one, have not tried manual agitation with my Orbital. Could this be the main problem? Maybe the modifications are only useful for lazy B's like me who can't be bothered to use elbow power? The mods I've carried out ensure "perfect" negs for me - but perhaps they would be of little use to someone who manually agitates the processor? Just a thought!
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