Developing time for FB paper

pentaxuser said:

So from the technical data sheet is it not possible to work out a replenishment rate?

Click to expand...

No.

pentaxuser said:

For simplicity let's say that I use MG developer and RC paper only ( which is actually the case) Ilford says I can do 100 sheets of 8x10 with 1 ltr. So if I do 10 sheets in a session I have used 10% of that 1 litre's capacity in which case I replenish that one litre with 10% of fresh developer which is 100ml

Click to expand...

Here's a better way to look at it. The fresh developer has a certain concentration of "developing agent" according to Ilford's manufacturing specs. Per your example "... if I do 10 sheets in a session I have used 10% of that 1 litre's capacity..."

So you presumably have used up something like 10% of the "reserve quantity" of the "developing agent." Whatever this actual amount is, it's clear that the concentration of "developing agent" is now less than 100% of the original specification. So the question is, how much of that "fresh developer" do you need to add to bring that used developer back to the original 100% concentration of "developing agent?"

In case the answer is not obvious, you would have to replace ALL of the used developer. This is the reason why a proper replenished system uses a special replenisher formula; it will be extra-strong with respect to concentration of the "developing agent." So one is able to use a moderately smaller amount of developer replenisher to bring the used developer back to 100% of spec for "developing agent" concentration.

Now, in the real world there is probably a lot of tolerance in the Ilford paper developer, so one could probably find, by trial and error, a "usable" method of periodically splashing some quantity of fresh developer into the tank. But I don't know if this would bring cost savings or not. All things considered a small scale user is probably better off to just follow the manufacturer's instructions.

FWIW an example of a "proper" replenished developer system would be Kodak's C-41 (color neg film) process. It's replenisher is designed to 1) dilute the byproducts of development down to spec, 2) restore the developing agent concentration back to spec, 3) bring the antioxidant package back to spec, and 4) keep the correct pH. The replenishers typically come in several versions depending on your process conditions. So this gives one an idea of what would be involved in making a proper b&w replenisher.

pentaxuser said:

So from the technical data sheet is it not possible to work out a replenishment rate? For simplicity let's say that I use MG developer and RC paper only ( which is actually the case) Ilford says I can do 100 sheets of 8x10 with 1 ltr. So if I do 10 sheets in a session I have used 10% of that 1 litre's capacity in which case I replenish that one litre with 10% of fresh developer which is 100ml

Now bear in mind that I have said before when giving my reasons for not trying factorial development that I have a Nova slot processor. The nature of the slots means that less than an inch of developer is exposed to the air and at the end of the session the slot is covered by a tube and in my case cling film forming an air tight barrier or as near as makes no difference so the next night the developer is as good as it was the night before when for sake of argument I do another 10 prints and now the 2 day old developer has only 80% of the original developer. In 10 days the developer has changed completely

Do I do 10 prints a night? Yes, I have done but not on a regular basis of night after night and in addition I may do no printing at all for weeks when even the life of my developer in its Nova slot may have expired and I do not want to take a chance of using it.

Click to expand...

I tried to track down the manuals for Nova processors with limited success. I found one relating to the black and white processors. It was two pages and didn't mention replenishment or life of the developer. It is possible that what I found was the first part of a longer manual which did address those points. I also found a manual for Nova color processors. It suggested a replenishing schema, but then color print developers are designed for replenishment, so that came as no surprise. The manual said that the life of the color print chemicals was weeks, also no great surprise.

So my question is are you using the color print developer replenishment schema for black and white developers which are not designed for replenishment? How long (time) are you using your black and white developer, with or without replenishment, before tossing it and starting with fresh developer? Days? Weeks? Months?

Roger Cole said:

I DID read it, thankyouverymuch. That said absolutely nothing about what YOU ACTUALLY DID.

Click to expand...

This is exactly what I wrote before -- and exactly what I did:

7. Test for fog from too long a development time.

• A. Turn off all lights, including the safelights.
• B. Cut an 8x10 sheet of paper into 1 inch strips.
• C. Fix and wash an unexposed, undeveloped strip of paper as determined in the first tests. This will be your comparative strip with no development.
• D. Develop each additional strip for 1, 2, 3, 4, 5, 6, 7, etc. minutes. Then fix and wash, as determined in earlier tests.
• E. Compare strips. Any greying, even a little, indicates fogging due to too long a development time. With most papers, usually anything less than five minutes is OK. Run fine-tuning tests if you think they are appropriate.

Mr Bill said:

No.



Here's a better way to look at it. The fresh developer has a certain concentration of "developing agent" according to Ilford's manufacturing specs. Per your example "... if I do 10 sheets in a session I have used 10% of that 1 litre's capacity..."

So you presumably have used up something like 10% of the "reserve quantity" of the "developing agent." Whatever this actual amount is, it's clear that the concentration of "developing agent" is now less than 100% of the original specification. So the question is, how much of that "fresh developer" do you need to add to bring that used developer back to the original 100% concentration of "developing agent?"

In case the answer is not obvious, you would have to replace ALL of the used developer. This is the reason why a proper replenished system uses a special replenisher formula; it will be extra-strong with respect to concentration of the "developing agent." So one is able to use a moderately smaller amount of developer replenisher to bring the used developer back to 100% of spec for "developing agent" concentration.

Now, in the real world there is probably a lot of tolerance in the Ilford paper developer, so one could probably find, by trial and error, a "usable" method of periodically splashing some quantity of fresh developer into the tank. But I don't know if this would bring cost savings or not. All things considered a small scale user is probably better off to just follow the manufacturer's instructions.

FWIW an example of a "proper" replenished developer system would be Kodak's C-41 (color neg film) process. It's replenisher is designed to 1) dilute the byproducts of development down to spec, 2) restore the developing agent concentration back to spec, 3) bring the antioxidant package back to spec, and 4) keep the correct pH. The replenishers typically come in several versions depending on your process conditions. So this gives one an idea of what would be involved in making a proper b&w replenisher.

Click to expand...

Thank you Mr Bill So on that basis the Xtol replenishment method of 65-70 ml of stock is not proper replenishment but seems to work. I based this on statements from its users some of whom are experienced and appear trustworthy So by the same token isn't a replenishment system with MG possible and will work to the extent of reproducing the same quality of prints that to all intents and purposes look the same to the viewers eye even if on the basis of what you have said there would be differences in the prints if measured with an appropriate instrument?

Can I ask; Is it your interpretation of what Ilford is saying is that in its quoted 100 prints with the same 1ltr print 100 will be identical to print 1 and what do you think happens after print 100. Does the quality "fall of a cliff" as they say within a few prints?

Thanks

pentaxuser

Photo Knowledge said:

What is RTFM?

Click to expand...

Read The Friendly Manual <=== the polite version

Photo Knowledge said:

What is OP? And yes I got some knowledge and now since I'm familiar with the site I'll post questions where they are supposed to go. I don't need to be given a hard time I'm just learning and it's my first time ever joining a website like this!

Click to expand...

OP is the original poster. In this thread you.

Photo Knowledge said:

What is OP? And yes I got some knowledge and now since I'm familiar with the site I'll post questions where they are supposed to go. I don't need to be given a hard time I'm just learning and it's my first time ever joining a website like this!

Click to expand...

None of us was born with this knowledge. It takes time for every thing to fall into place. We will help you get there.

Pieter12 said:

It just seems like an exercise of limited use. Why bother? I would only test for maximum black if I was not satisfied with the blacks in a print for some reason. There are data sheets for recommended development time, an excellent starting point, plus paper has a wide latitude for development to completion.

Click to expand...

I agree. Most of us have a real life and do not need to get into endless testing of every single part.

pentaxuser said:

So from the technical data sheet is it not possible to work out a replenishment rate? For simplicity let's say that I use MG developer and RC paper only ( which is actually the case) Ilford says I can do 100 sheets of 8x10 with 1 ltr. So if I do 10 sheets in a session I have used 10% of that 1 litre's capacity in which case I replenish that one litre with 10% of fresh developer which is 100ml

Now bear in mind that I have said before when giving my reasons for not trying factorial development that I have a Nova slot processor. The nature of the slots means that less than an inch of developer is exposed to the air and at the end of the session the slot is covered by a tube and in my case cling film forming an air tight barrier or as near as makes no difference so the next night the developer is as good as it was the night before when for sake of argument I do another 10 prints and now the 2 day old developer has only 80% of the original developer. In 10 days the developer has changed completely

Do I do 10 prints a night? Yes, I have done but not on a regular basis of night after night and in addition I may do no printing at all for weeks when even the life of my developer in its Nova slot may have expired and I do not want to take a chance of using it.

However for those using trays who do lengthy printing sessions at a time and then pour the developer back into bottles and then do the same again the next day/night, I can see that in their case factorial development might enable them to use that same 1ltr rather than dump it and start afresh and still get the same quality of prints. If they were regular printers then in addition to producing the same quality over a session and over time, it gives them a cost saving. Are those factors big enough to be bothered about and is it worth it for most printers? I don't know. Is it worth it for you? No, by the sound of it but it clearly is for others who use that method and I can see the logic of doing it.

There's not much more for us to exchange now by way of extra discussion, is there? I don't think it will get either of us any closer to agreement. except maybe on this last point, namely, that we won't get any close to agreement

It has been an interesting discussion however

pentaxuser

Click to expand...

I do not bother to replenish fixer. After about 100 photographs I dump the fixer and make a new batch.

I only mix enough of anything for a single day's session, then toss it.

DREW WILEY said:

I only mix enough of anything for a single day's session, then toss it.

Click to expand...

Same for me.

pentaxuser said:

Thank you Mr Bill So on that basis the Xtol replenishment method of 65-70 ml of stock is not proper replenishment but seems to work.

Click to expand...

Yes, in my view replenished Xtol is NOT a "proper" replenished system. Although it "seems to work" the result is NOT the same as a fresh Xtol mix. I see it (replenished Xtol) as something of a "kludge" that more or less works as a lower activity version of original Xtol. As such it has some of the advantages of a proper (in my view) replenished system, and this working system can be maintained without much critical attention.

In contrast to this a replenished C-41 developer should result in exactly the same activity level as a fresh mix, and this can be maintained indefinitely. There are versions, such as Kodak LORR, that can run with a replenishment rate 2 or 3 times lower than that of Xtol-R, where chemical costs are in the area of 10 times lower than single use C-41. But... these systems take special attention, in the form of equipment and labor, to maintain a stable process. So this is one tradeoff of such a system.

pentaxuser said:

So by the same token isn't a replenishment system with MG possible...

Click to expand...

I would say that if Ilford designed it as a replenished system then definitely it is possible. Otherwise, I can't say for sure. (I could hypothesize about this all day but the bottom line is that I don't know for sure.)

Fwiw there used to be a number of options for replenished paper developers. In my earlier days, still wet behind the ears, of doing photo lab QC work, we ran a dedicated processing machine for rolls of double weight b&w fiber base paper. (For anyone who might remember it was a Kodak 4C type machine, leader-fed continuous machine, using something like a 5-foot diameter drum dryer.) We ran mostly 10 or 11 inch wide rolls, although the machine could probably handle 16", maybe 20" wide. This machine was also setup with an optional Kodak Polytoner step, depending on the choice of the department printing the work. Everything was replenished via rotameters, manually set by the operator according to paper width.

Kodak used to have machine-process versions of their more commonly known professional developers. Many here are probably familiar with Selectol developer. The machine version, designed for replenishment, was named, as I recall, Selectomat, and this is what we ran on this particular machine. If the machine had to be refilled from scratch it was done using a combination of "starter solution," water, and Selectomat replenisher. I have little doubt that Ilford, in the day, had similar products. But being in the US Kodak was our main source of materials, with a Kodak TSR spending probably a couple half-days per week in our facility. All of this stuff was new and exciting to me, things one never heard about outside of actual labs. Advancing my photo education by basically working cheap.

pentaxuser said:

Can I ask; Is it your interpretation of what Ilford is saying is that in its quoted 100 prints with the same 1ltr print 100 will be identical to print 1 and what do you think happens after print 100. Does the quality "fall of a cliff" as they say within a few prints?

Click to expand...

No, quality does not "fall off a cliff." Rather the developer activity just gradually falls off more and more. For some time one can deal with this, but eventually something has to be done.

Most of the people here, I think, are making exposures, then developing, then evaluate, etc. In the good old days commercial lab work was typically exposed in one place (in rolls) then taken to the processing machine where the operator would process the roll(s) under standard conditions. Then the printer would make corrections and reprint. Now, it might be hours between cycles, so it was necessary that the processing machine produce stable results. Otherwise it becomes a moving target for the printer.

As a QC guy in those days it was our job to keep the machines stable. We had the operators process control strips periodically, then we read and plot on a chart. As the contrast or overall density slowly drifts off we make adjustments to the replenishment rates. (We periodically make calibration charts for the rotameters so we can easily get the necessary settings for a rate change. ) Then we tape some new pointers on the rotameter for the different paper widths.

Periodically the operator forgets to turn a replenisher on or off, so developer activity shifts. There might be hours worth of already exposed paper which will become trash if processed under those conditions. So it becomes necessary to try to restore the processing machine to its aim activity level.

It's a completely different situation from what a hobbyist does in their own darkroom, developing by eye in a tray.

Depends on the developer. Some are capable of being replenished; others do suddenly drop off a cliff at a certain point, even within a single day. And even in the cases when replenishment is hypothetically realistic, most amateur darkrooms don't have the kind of sophisticated monitoring and automated replenishment machines that big commercial labs do. I'd rather not worry about the issue and its effects at all, so only mix enough of anything for my own daily session needs. I'm way more interested in negative and print quality rather than quantity.

Developers die from use or age -- just like us. Add use & age together and you have a recipe for disaster. You'll never really know when it dies, sometimes quickly, but it usually just dies off slowly -- just like us.

That's why I use fresh chemicals with each print -- it's easier and cheaper.

xkaes said:

Developers die from use or age -- just like us. Add use & age together and you have a recipe for disaster. You'll never really know when it dies, sometimes quickly, but it usually just dies off slowly -- just like us.

That's why I use fresh chemicals with each print -- it's easier and cheaper.

Click to expand...

Each print? That seems excessive.

When developer does start drifting, it's perfectly obvious print to print, provided one actually looks at them. But with experience, we learn what to expect, and when. I know how long one of my typical work sessions is going to be, and how many sheets of paper will be involved, both final and trial ones. If the session is going to be excessive, I will prioritize the images I want cooler toned and harder contrast first, and the ones more amenable to a softer rendition last. I don't need a calculator to figure any of this out. My own eyes do it better.

DREW WILEY said:

When developer does start drifting, it's perfectly obvious print to print, provided one actually looks at them. But with experience, we learn what to expect, and when. I know how long one of my typical work sessions is going to be, and how many sheets of paper will be involved, both final and trial ones. If the session is going to be excessive, I will prioritize the images I want cooler toned and harder contrast first, and the ones more amenable to a softer rendition last. I don't need a calculator to figure any of this out. My own eyes do it better.

Click to expand...

Yes indeed....

DREW WILEY said:

Depends on the developer. Some are capable of being replenished; others do suddenly drop off a cliff at a certain point, even within a single day.

Click to expand...

Yeah, I guess "drop off a cliff" sorta depends on how one views or defines the time frame. Ignoring things like the self-destructive A and B litho developers I would say that nearly every developer has a predictable pattern of losing activity before complete death.

If your definition of "sudden death" is fine one day, totally dead the next, I'd say there is a point somewhere between the two where a test strip shows significant degradation. So again, it depends on how one defines things.

Someone else might say, this developer was fine two weeks ago... maybe a month, and today it's totally dead - so they consider it to be sudden death.

Reminds me of those old antique photos where they didn't change the developer or fixer until there were bullfrogs in it.
That bad habit led to a lot of splotchy fading and differential "bronzing" over time, due to improper fixing in particular. I found certain examples of that to be downright beautiful, when thumbing through stack of antique silver prints. But I didn't want anything fugitive about my own prints, so learned to mimic the look via split toning.

DREW WILEY said:

Reminds me of those old antique photos where they didn't change the developer or fixer until there were bullfrogs in it.

Click to expand...

Right. I don't want bullfrogs in my developer either. That's where I draw the line. Tadpoles are okay, they provide gentle agitation, but you have keep an eye out for bullfrogs. They sort of sneak up on you if you are not vigilant. Also, those webbed feet leave splotches on your underdeveloped prints, compounding the problem. That's why I replace my developer early and often. Besides I don't want to spend the extra time watching a print slowly develop during extended development.

Mr Bill said:

Yes, in my view replenished Xtol is NOT a "proper" replenished system. Although it "seems to work" the result is NOT the same as a fresh Xtol mix. I see it (replenished Xtol) as something of a "kludge" that more or less works as a lower activity version of original Xtol. As such it has some of the advantages of a proper (in my view) replenished system, and this working system can be maintained without much critical attention.

In contrast to this a replenished C-41 developer should result in exactly the same activity level as a fresh mix, and this can be maintained indefinitely. There are versions, such as Kodak LORR, that can run with a replenishment rate 2 or 3 times lower than that of Xtol-R, where chemical costs are in the area of 10 times lower than single use C-41. But... these systems take special attention, in the form of equipment and labor, to maintain a stable process. So this is one tradeoff of such a system.

Click to expand...

If one comes from a colour film background, as Mr. Bill certainly does, a "true" replenishment system needs to be interchangeable with a system that uses fresh chemicals, including using the exact same development times, and providing the exact same contrast response for all colours.
As X-Tol replenished doesn't need to do that, it differs.
I would argue that it is best to consider replenished X-Tol on its own - essentially as a different developer. If you do that, and you like its performance, than the question becomes does it do what it does consistently, when appropriately maintained.

Mr Bill said:

No, quality does not "fall off a cliff."

Click to expand...

It can, it depends on the developer volume and size of paper. if you are processing 4x6 prints in a large volume of developer the reduction in activity isn't very noticeable. A lot different for processing a 20x24 print, when you could see a lot of variance from sheet to sheet, depending on the developer volume in the tray.

xkaes said:

Developers die from use or age -- just like us. Add use & age together and you have a recipe for disaster. You'll never really know when it dies, sometimes quickly, but it usually just dies off slowly -- just like us.

Click to expand...

UNLESS you're running a proper replenished system, with appropriate "monitoring." In this case the developer can essentially live "forever."

If you had started up a proper replenished C-41 system, say 10 or 20 years ago, and nothing specific happened to destroy the developer, it could still be producing the exact same processing quality as it did then.

The thing with a replenished system is that new developer is constantly being introduced into the system while old is constantly being flushed out. So the thing essentially becomes a steady-state system. But... there are conditions to be met - you need some minimum quantity of film to be processed, you can't let the developer become overly oxidized, etc.

Craig said:

It can, it depends on the developer volume and size of paper. if you are processing 4x6 prints in a large volume of developer the reduction in activity isn't very noticeable. A lot different for processing a 20x24 print, when you could see a lot of variance from sheet to sheet, depending on the developer volume in the tray.

Click to expand...

Well yeah, you're right. But I would make the case that the developer is being a bit abused, or at least being used in a situation where one is going against generally accepted practice. Where the quantity of paper in one shot is excessive for the quantity of developer.

If, instead of the entire sheet of 20x24" paper, you tore it in half (yeah I know this would be a dumb thing to do) and first developed one half, then I would say you would see more of a gradual degradation of the developer.

Someone might also say, what if I bubble oxygen through the developer for a while, won't that cause sudden death (of the developer, not the guy making bubbles)? So yeah, that would do it in pretty short order. (I would probably consider that to be sudden death.) I should probably be more careful with the set up conditions when I make posts.