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> Paterson Orbital processor revisited |
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#21
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Dave and Paul - When you refer to "manual agitation", don't forget that it's not that random. Putting the tank on to its base does guide your movements, the only un-automated factor then being the speed of agitation.
I'm trying another subvariant of my "mat" experiment, as I turned up some sheeting I bought to stick to a shoulder bag's sling, to stop it slipping off my arm. Unlike my solid silicone mat, this stuff is mesh and a bit thinner. My last run of 4 sheets showed even development and no sign of vane interference; so this stuff might be a further improvement. |
#22
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By manual agitation I mean not using a base at all, so that the agitation is random.
I should explain for those unfamiliar with this equipment, and trying to follow this discussion, that the unit was supplier with a separate base on which the tray was placed and rocked by hand. This gave a imparted a rotating motion. An optional accessory was an electrically motorised based that provides the same rocking movement. I can now understand what you are describing Paul, that the film can float up under the action of the swirling chemical and hit the bottom of the vanes. That makes sense, except it's something I've not experienced, maybe my dev is thicker than yours. Have you tried using some spoilt negatives and a water fill to use the unit without the lid fitted to observe what happens? |
#23
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I have always developed 5 x 4 sheet film in an open dish, but recently aquired a Paterson orbital processer without the base. I glued some cocktail sticks to the base of mine, two under each sheet of film, using waterproof Anglers Superglue, and was ready to start using it when I came across this thread. So I started experimenting as Dave suggested, and discovered the following:
1. 300 mls of liquid is not enough to cover the outer edges of the film. 500mls barely covers them. 600 mls does the trick but initial vigorous agitation is needed to get the film sheets to sink. 2. There is a headroom gap of at least 10mm between the top of the cocktail sticks and the plastic fins, so once the film has sunk it shouldn't come in contact with the fins. So I will try some film but will use 600mls and give initial vigorous agitation, to sink the film. And keep my fingers crossed.... Alan Clark |
#24
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Alan, I don't think that you and Dave are correct in thinking that so much fluid is necessary. The largest amount of developer I have used has been 180 ml; and uneven development has simply not been an issue. The only problems I've had, in four separate runs now, are (a) one sheet being marked by the vane when my mat was under the vane and (b) my first four sheets needing a separate wash to remove the anti-halation coating.
In addition, I think that 10mm is quite an over-estimate of the space between the cocktail stick and the bottom of the vane. Dave did a test with modelling material, which he refers to earlier. |
#25
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Quote:
I was sceptical at first but you can prove the theory by trying it with some scrap negatives (or some recently processed negatives at the washing stage) and putting water in with the lid off. My modification was to score the base so the negatives will still be at the intended height. If you add dots of glue or silicon or use some other anti-stick method which raises the negatives slightly then it is possible that a bit more solution is needed but it wouldn't be much. Steve. |
#26
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I use an Orbital for development of N+/- negs. I bought mine from a fellow UKLFPGer with small blobs of silcone sealant distributed over the bottom to ensure removal of the AH layer, the standard red pegs and with the vanes intact.
I use 200ml of developer and when it comes to agitation, I use a manual base, rotating slowly in one direction for two or three turns, then reversing the direction for the next two or three turns; I don't get any problems of swirl marks from the blades. Alan, part of the method for the Orbital is that the film is not covered at all times, otherwise you tend to get a different rate of development. Don't forget that the developer is acting at a reducing rate as it gets left on the film. I have found that, despite what could be regarded as continuous agitation, because the film is not covered all the time, there is no need to reduce the development time, as I would when using my Jobo ATL1500; now that is truly constant agitation!! As Dave did, I experimented with various levels of developer (with the lid off) and found that 200ml seemed to be an optimal choice between the Yorkshireness () of less developer and the possibility of developer slopping out. |
#27
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Quote:
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#28
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I don't do much 5x4 but I'm sure I use more than specified despite confirming for myself that the Paterson specified 60ml (or whatever it is) was enough. 100ml (or even 150ml) is still a small amount compared to 600ml for a 120 film. Steve. |
#29
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I have never used these tanks but one thought occurs is whether the 60ml or whatever you use contains enough active ingredient to develop the film correctly. This is rarely a problem with large tanks that hold several hundred millilitres or developers but 60ml of Rodinal at 1:25 means only about 2.5ml of stock when Agfa recommend (IIRC) 10ml stock per roll of 35mm film (or four sheets of 5x4").
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#30
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Quote:
Anyone care to experiment? |
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