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  #11  
Old 8th January 2014, 09:10 PM
JOReynolds JOReynolds is offline
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Default Excess grain from continuous agitation?

Can any theoreticians explain why continuous agitation should encourage clumping of partly-reduced silver halide crystals during development?
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  #12  
Old 8th January 2014, 09:38 PM
Rob Hale Rob Hale is offline
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Hi Alastair,
Ummm sheet film and Rodinal. I use Rodinal in Jobo drums a lot and don’t have a problem with grain so I wonder what you do differently.
How many cc /mls of Rodinal stock ( liquid ex the bottle ) per sheet of 4x5 do you use ?
Regards
Rob.
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  #13  
Old 8th January 2014, 09:42 PM
Mike O'Pray Mike O'Pray is offline
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Good question. I suspect I may have seen an answer or possibly several answers on another forum but cannot now recall what they were.

I think I have a better chance of remembering answers I see on this forum. More isn't always better.

So I look forward to learning something.

Mike
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  #14  
Old 8th January 2014, 10:18 PM
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dsallen dsallen is offline
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A two-bath developer such as Thornton's will give you excellent results provided that the subject has normal to high contrast. The key characteristic is that it stops blown-out highlights which happen with many 'normal' developers when used for continuous development.

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  #15  
Old 13th March 2014, 10:00 AM
JOReynolds JOReynolds is offline
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I added the text below to another thread but it did not appear in the 'New Posts' section, so here it is again.
I'd like to put in a good word for XTOL in rotary processing. Around twelve years ago I had to write process sequences for a rotary-discard machine that we were developing (sorry for the pun) for processing odds and sods in minilabs. One of the requirements was that all sequences, including B&W, should work well at elevated temperatures (think midday without air-conditioning in a tropical minilab). I discussed this with experts at several industry specialists and we reckoned that we needed to get good results with Kodak, Ilford, Fuji and Agfa monochrome films at up to 30°C. We did not test other brands. Because development times might be quite short we decided to incorporate a temperature-controlled pre-rinse. This helped with even initial wetting and ensured that the stainless-steel reels (loaded with the help of an infra-red TV camera) did not depress the developer temperature. Then I exposed many rolls of test film to a target intended to show up streaking (a black blob on a white background and a white blob on a black velvet background). Since whichever developer was drawn from a tank below the drum, it had to have good storage characteristics in ready-to-use form. The tank had a capacity of 5 litres and had a floating lid.
None of the films tested in any of the usual developers at 24°C reticulated or edge-frilled - a good start. I persuaded some technicians at Kodak Harrow to measure granularity with their microdensitometer - no change in frequency or amplitude from 20°C. But XTOL 1+1 stood out in three areas - the keeping qualities were good, there was remarkably little streaking (which has always been a problem with rotary processors) compared with D76 and Microphen and it was the only developer that did not cause edge frilling at 30°C (slitting weakens the cut edge of the emulsion, which causes little threads and fronds to separate and float off in the developer).
Unlike C41, for which standardised process control strips are available, there is no reference for B&W speed and contrast, so development times were decided by the suck-it-and see method. That was before Ilford's excellent time/temperature graph and the Massive online database. I regret not testing Rodinal, which I now use in a standard inversion tank, but its legendary longevity may not have worked when stored diluted 1+50.
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  #16  
Old 13th March 2014, 10:49 AM
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richardw richardw is offline
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Quote:
Originally Posted by Alastair View Post
Hey all,

Looking for some advice on developer suitable for continuous agitation in my Paterson Orbital. I'm currently using Rodinal but have found that it becomes very grainy when you agitation throughout the development stage. I'm ideally looking for a liquid developer that I can use as and when rather than mixing up powder a la D76.

I tend to use TMax 100 and 400 although have a bunch of Tri-X in the fridge as well as some Foma 400. All sheet film.

Thinking Ultrafin possibly but anything else that might be suitable?

Cheers!
How about not doing continuous agitation?

If you modify your Orbital a little, eschew the Orbital Base and instead stand the Processor flat on your worktop you can gain the benefits of semi-stand and stand routines, get more control over the highlights and avoid that grain problem.

http://freepdfhosting.com/f640343f29.pdf

Are you okay to make up your own developer from raw chemicals?

If so you might like to try OBSIDIAN AQUA for very fine grain and yet very sharp negatives.

http://freepdfhosting.com/aa330a94ce.pdf

On the second page of this pdf is how I prefer to use OBSIDIAN AQUA, which could be a starting point for you to work from towards your own preferences...

http://freepdfhosting.com/3e906fe75d.pdf

That constant agitation routine is okay for colour with the minimum amount of solution in at a time but for panchromatic film you get more control and versatility with intermittent agitation routines. OBSIDIAN AQUA is so economical it matters not a jot that you use 500ml of working solution each time instead of 50 to 150ml.

richard
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  #17  
Old 13th March 2014, 10:59 PM
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Bill Bill is offline
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Quote:
Originally Posted by JOReynolds View Post
I added the text below to another thread but it did not appear in the 'New Posts' section, so here it is again.
I saw is as a new post when you posted it in the other thread.

I think that you will not have seen it as a new post is because your own posts do not show up. It is only the posts by others that will show.

Hope this clears things up.

Bill
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  #18  
Old 14th March 2014, 09:59 AM
JOReynolds JOReynolds is offline
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Thanks, Bill
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