Paper Chemistry for Machine Processing?

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I'd like to try running B&W RC paper in the Jobo ATL, and we're also acquiring a Colex Colette 20" RT processor. This is designed for RA4 but of course suitable for B&W as well. Just looking for recommendations on chemistry suitable for machine processing.
 

Tom Kershaw

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I'd like to try running B&W RC paper in the Jobo ATL

Considering the small volumes involved in Jobo rocessing, I'd look at simple one-shot development with Ilford Multigrade developer or similar.

For machine processing I have used ILFORD 2000 RT in the past, run through a Thermaphot 20" RT processor with good results.
 
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Considering the small volumes involved in Jobo rocessing, I'd look at simple one-shot development with Ilford Multigrade developer or similar.

For machine processing I have used ILFORD 2000 RT in the past, run through a Thermaphot 20" RT processor with good results.

I'd been using Moersch ECO 4812 recently because of it's long keeping properties. And of course TF5. Maybe I'll write to Moersch to ask about use in a rotary system, temps, etc. When you can run the developer at very specific temps and it's going to be subject to a lot of agitation I think the conditions are different enough from a tray to warrant asking if it's a good idea.
 
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Does anyone know if I should adjust the processing time for rotary? I'm not sure if paper process developers are 'too completion' or not. Normally in Eco I do 2 minutes for RC.
 

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I'm not sure if paper process developers are 'too completion' or not.

Yes, in principle, they are. I say 'in principle' because of two reasons:
1: A pure 'to completion' process would theoretically give the same tonal scale and dmax even if the print is developed infinitely. Clearly, in reality, at some point the print starts to fog, so there's a limit to how far you can take this.
2: There may/will be subtle differences in tonal rendering between two prints that are both developed 'long enough', but one being developed significantly longer than another. If these differences are meaningful enough to worry about, I leave up to you to decide.

Personally I'd be inclined to keep it as simple as possible and determine a minimum development time for which additional development gives to appreciable change in print densities, and a maximum development time that does not yet result in fogging or meaningful changes in the h/d curve. Then you have a window you could stay in without having to worry too much about very subtle differences within that window.
 
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Yes, in principle, they are. I say 'in principle' because of two reasons:
1: A pure 'to completion' process would theoretically give the same tonal scale and dmax even if the print is developed infinitely. Clearly, in reality, at some point the print starts to fog, so there's a limit to how far you can take this.
2: There may/will be subtle differences in tonal rendering between two prints that are both developed 'long enough', but one being developed significantly longer than another. If these differences are meaningful enough to worry about, I leave up to you to decide.

Personally I'd be inclined to keep it as simple as possible and determine a minimum development time for which additional development gives to appreciable change in print densities, and a maximum development time that does not yet result in fogging or meaningful changes in the h/d curve. Then you have a window you could stay in without having to worry too much about very subtle differences within that window.

Is there a minimum development time test?
 

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I'd expose some step wedges and develop them for increasing amounts of time. Compare them (visually, or by measurement) and note the shortest time that gives full development and after which no change occurs. Not sure if it's documented somewhere; I'm sure it must be, but it's quite straightforward I think.
 
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I'd expose some step wedges and develop them for increasing amounts of time. Compare them (visually, or by measurement) and note the shortest time that gives full development and after which no change occurs. Not sure if it's documented somewhere; I'm sure it must be, but it's quite straightforward I think.

The term full development is misleading, it should be the minimum time to reach Dmax plus around another 10 to 20% safety factor. The problem is extending development longer shifts the mid tones and blocks up the shadow details.

Unfortunately MG is not as long lasting as I need it to be. One of the benefits of Eco is that it lasts I think like 8 months when kept in full bottles.

I mix my own PQ print developers based on Ilford published formulae using Phenidone, however to commercial strength, using Potassium Carbonate and Hydroxide instead of Sodium Carbonate. I find the shelf life is a lot better even in partially filled bottles than the reformulated Ilford Dimezone versions. I'm talking about over a year in partially filled bottles..

You need a developer like 2000 RT because it's specifically designed for self replenishment in an RT machine, I'm sure other developers would work initially, but you run the risk of much earlier collapse with some formulae, making them significantly less economic.

Ian
 

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Would LPD work in this instance? It is self replenishing. It's also fairly inexpensive, one shot use in JOBO wouldn't break the bank.
 
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The term full development is misleading, it should be the minimum time to reach Dmax plus around another 10 to 20% safety factor. The problem is extending development longer shifts the mid tones and blocks up the shadow details.



I mix my own PQ print developers based on Ilford published formulae using Phenidone, however to commercial strength, using Potassium Carbonate and Hydroxide instead of Sodium Carbonate. I find the shelf life is a lot better even in partially filled bottles than the reformulated Ilford Dimezone versions. I'm talking about over a year in partially filled bottles..

You need a developer like 2000 RT because it's specifically designed for self replenishment in an RT machine, I'm sure other developers would work initially, but you run the risk of much earlier collapse with some formulae, making them significantly less economic.

Ian

I forgot to update this thread, totally spaced. I'm going to stick with RA4 in the Colex and try to do RC B&W processing in the Jobo ATL 2500. That's why I'm considering Eco 4812. It'll do a lot of sheets and lasts for months. If I keep 5L in the self re-filling system and track the sheets it could be pretty efficient. I'm just not sure what time and temp to use. The Jobo can do around 21-24C with no problem. Might have a hard time maintaining 20C in the warmer months.
 

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I'd expose some step wedges and develop them for increasing amounts of time. Compare them (visually, or by measurement) and note the shortest time that gives full development and after which no change occurs. Not sure if it's documented somewhere; I'm sure it must be, but it's quite straightforward I think.

Good idea!
 

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I forgot to update this thread, totally spaced. I'm going to stick with RA4 in the Colex and try to do RC B&W processing in the Jobo ATL 2500. That's why I'm considering Eco 4812. It'll do a lot of sheets and lasts for months. If I keep 5L in the self re-filling system and track the sheets it could be pretty efficient. I'm just not sure what time and temp to use. The Jobo can do around 21-24C with no problem. Might have a hard time maintaining 20C in the warmer months.

I've done some totally uncontrolled experiments using a Kodak Rapid Color processor. These things are like Uber Jobos, extreme agitation. I had Bromophen, so I used Bromophen. I was even processing at 95-100°F. Totally crazy, but I was getting prints, RC and fiber.
I think the Jobo would work well at much lower temperatures (I was just playing) . Fogging would be my concern. I had a chance to get 3 Ilford 2150 processors for free! Instead my friend sawed them up with a Sawzall. Parts were saved.
 

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I forgot to update this thread, totally spaced. I'm going to stick with RA4 in the Colex and try to do RC B&W processing in the Jobo ATL 2500. That's why I'm considering Eco 4812. It'll do a lot of sheets and lasts for months. If I keep 5L in the self re-filling system and track the sheets it could be pretty efficient. I'm just not sure what time and temp to use. The Jobo can do around 21-24C with no problem. Might have a hard time maintaining 20C in the warmer months.

Forget the Jobo ATL for B&W prints, it's an unnecessary and complete waste of your time, very slow, just dish process with a timer. I used to help a friend, a top commercial/advertising photographer on his longer print runs, that would be hundreds of prints off each negative. It was easy.

You are overthinking making B&W RC prints.

Ian
 

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Thought I'd clarify why the ATL is not commercially viable for B&W RC prints, the time loading it the process cycle, uneconomic in terms of chemistry, the cleaning/drying etc. Fantastic for film processing, or for colour prints.

The Colex is as you've decided better for your colour print processing, if you ultimately want an RT machine for B&W there are simpler/cheaper options. One advantage of dish processing is it is cheap, you can process a few prints in a tray at the same time. A print dryer might be useful.

Ian
 
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Thought I'd clarify why the ATL is not commercially viable for B&W RC prints, the time loading it the process cycle, uneconomic in terms of chemistry, the cleaning/drying etc. Fantastic for film processing, or for colour prints.

The Colex is as you've decided better for your colour print processing, if you ultimately want an RT machine for B&W there are simpler/cheaper options. One advantage of dish processing is it is cheap, you can process a few prints in a tray at the same time. A print dryer might be useful.

Ian

Oh I'm not so sure still. Certainly 8x10s are easy to crank out in trays but 16x20s and 20x24s could hold some advantages with rotary. I think chemical usage would in fact be more economical because I can just pour the 'just used' solution back into the working bottle and go on. Plus the ATL 2500 has floating lids in the re-fill tanks and the tempered bottles are pretty full at all times. At the very least I'll try it out.

For dryer, I have an Arkay RC 2100. As I get older, and I'm not that old, time is so much more important to me so I've set up efficiencies where I can.
 

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Oh I'm not so sure still. Certainly 8x10s are easy to crank out in trays but 16x20s and 20x24s could hold some advantages with rotary. I think chemical usage would in fact be more economical because I can just pour the 'just used' solution back into the working bottle and go on. Plus the ATL 2500 has floating lids in the re-fill tanks and the tempered bottles are pretty full at all times. At the very least I'll try it out.

For dryer, I have an Arkay RC 2100. As I get older, and I'm not that old, time is so much more important to me so I've set up efficiencies where I can.

I picked up a couple Jobo 3005 sheet film drums. These work nice for processing prints. I use the Ilford RC print dryer, that like your Arkay is fabulous.
 

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I print up to 24"x20", sometimes larger with a 40" wide rolls of paper, but my regular sizes are 16"x12" or 20"x16", almost all Fibre based papers. RC papers are easier to handle and have shorter development times.

It would be worth trying dish processing and the ATL 2500 for the larger sizes to see which is the faster work flow.

Ian
 

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If you have lots of money and are processing murals these are amazing
 
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If you have lots of money and are processing murals these are amazing

Biggest I'd go is 20x24. After that chemical processing gets crazy. That's what inkjet is for!
 
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