Dektol used stock... How long can I re-use it?

Hello everyone,

I've been using 3 liters of (homemade) Dektol stock to process a bunch of contact-sheets.At the end of the session I poured the dev back in its jug.
Now I'd like to know if there's a method to know how many times I can re-use my Dektol (stock again)?

Ilford tech brochure says I should be able to use it for 2 months but I'm not that optimistic. Three weeks would be wonderful.

Thanks for all your replies and suggestions!

Dektol is a Kodak product. What Ilford brochure gives you advice on using Kodak products?

Beyond that, I'm used to diluting Dektol 1+2 for print development, and using it only for a single printing session (by the time I've developed a dozen or so prints, it should be getting rather exhausted anyway). On the rare occasions I've used it for film, I dilute 1+9 -- and again, discard after processing a single tank.

At a minimum, reusing stock solution that's had used developer mixed back in will reduce the activity of the developer. Most prints are developed to completion, but you may find, after using the stock solution for a number of printing sessions, that you start getting uneven development or losing contrast and highlight detail due to progressive exhaustion; extending tray time will likely fix this up to a point. Seems to me the Kodak publication on Dektol gives a number of prints you can develop in a given amount of 1+2 working solution -- it may also say something about capacity of the stock, if Kodak actually recommends using Dektol that way.

Um... stock solutions should be diluted for normal use. Print developers usually get used for only one or two sessions. Sometimes a full-strength stock solution gets used when one is striving for additional contrast, but otherwise there is no particularly good reason to use the undiluted stock solution to develop prints with, especially contact sheets.

What you should be doing is diluting your stock. (Homemade "Dektol" is likely D-72; or... what is that you really use?. If it is D-72, then 1+2 is the standard dilution. If it's something else, then the dilution may be different.) After a session or two, the developer will be oxidized to the point it is no longer useful and should be discarded.

Reusing print developer in the way you describe is really not best practice. The developer will gradually lose strength and the entire stock will become unusable. You'll get more prints out of it by diluting it and using it as directed.

Best,

Doremus

How many days can you leave a hamburger out before it makes you sick eating it? Pouring back anything sounds nuts to me.

Dektol, or at least what has been published as D-72 on digitaltruth.com, is my goto developer in a dark room I share with a few analog enthusiasts in my town. We typically meet once a week and run anywhere from 10 to 40 sheets.

We typically start with 2 liters of freshly mixed developer, and since dry paper soaks up developer and carries it into the stop bath, the amount of developer goes down over time. As a result, I have to mix a new batch every couple of months, and in times of lower throughput I sometimes mixed just one liter to top off the canister. I have not seen this developer going weak or inactive in all those years, except for periods of very low use, where a batch would sit around for >6 months.

In order for this to work you must not dilute the developer. Concentrated solutions dissolve less Oxygen, therefore Dektol stock lasts much longer than diluted working solutions. I have never had a problem developing prints in stock solution.

Thanks for all the replies and special thanks to Rudeofus for the heartwarming words! ;-)

There are print developers that are designed for re-use and long life - Liquidol comes to mind.

Given the high cost of printing paper relative to developer cost I'd hesitate to carry the developer over. If you must for a few hours, try floating a sheet of plastic wrap on the developer in the tray.

You can put a spritz of something that is heavier than air in the bottle to preserve it for a long time. I use butane but you could use the stuff to preserve wine or paint. Developer will last a really long time in a glass bottle that way. I've had them last over a year. Since I use different developers depending on my mood and I don't print all that often anymore, I've made this standard practice over the last few years.

Well, here's an interesting data point for genuine Kodak Dektol: today, I developed 1998-expired Tri-X 320 in Dektol I mixed at double stock strength in 2005, from (don't recall when) expired powder (and stored in a glass jar with minimum airspace). Diluted 1+9 (1+19 from the double stock), developed 6:30 with agitation ten seconds each minute, and the negatives look just fine. No excessive fog, normal looking contrast, and apparently normal speed (at least by eyeballing the negatives).

The real deal is some good stuff. That said, I still wouldn't develop anything in the stock solution without good reason -- the only application I've heard of for that is if you're hyper-pushing film (TriX 400 exposed at 3200 or higher, for instance) -- and I wouldn't reuse the stock without at least running some tests on film exposed for the purpose to determine how much to adjust development time. And, as noted, you'll get more film or paper developed more consistently by diluting the stock appropriately and discarding it after use.

Pat Erson said:

Hello everyone,

I've been using 3 liters of (homemade) Dektol stock to process a bunch of contact-sheets.At the end of the session I poured the dev back in its jug.
Now I'd like to know if there's a method to know how many times I can re-use my Dektol (stock again)?

Ilford tech brochure says I should be able to use it for 2 months but I'm not that optimistic. Three weeks would be wonderful.

Thanks for all your replies and suggestions!

Click to expand...

I use the 2 minute rule. The image should emerge within 2 minutes with a deep black. Exhausted developer will take longer for the image to come up and it’s hard to get a deep black.

Donald Qualls said:

The real deal is some good stuff. That said, I still wouldn't develop anything in the stock solution without good reason -- the only application I've heard of for that is if you're hyper-pushing film (TriX 400 exposed at 3200 or higher, for instance) -- and I wouldn't reuse the stock without at least running some tests on film exposed for the purpose to determine how much to adjust development time. And, as noted, you'll get more film or paper developed more consistently by diluting the stock appropriately and discarding it after use.

Click to expand...

I believe, that Pat wanted to use his batch of Dektol for printing on photographic paper, not for developing film. In Pat's case the use of stock solution makes a lot of sense. I can understand, how someone uses diluted print developer mixed from liquid concentrate, but when it comes to powder packs or home brew, I prefer concentrated soups and storage over 3-6 months.

Rudeofus said:

Dektol, or at least what has been published as D-72 on digitaltruth.com, is my goto developer in a dark room I share with a few analog enthusiasts in my town. We typically meet once a week and run anywhere from 10 to 40 sheets.

We typically start with 2 liters of freshly mixed developer, and since dry paper soaks up developer and carries it into the stop bath, the amount of developer goes down over time. As a result, I have to mix a new batch every couple of months, and in times of lower throughput I sometimes mixed just one liter to top off the canister. I have not seen this developer going weak or inactive in all those years, except for periods of very low use, where a batch would sit around for >6 months.

In order for this to work you must not dilute the developer. Concentrated solutions dissolve less Oxygen, therefore Dektol stock lasts much longer than diluted working solutions. I have never had a problem developing prints in stock solution.

Click to expand...

Rudi,

Let me get this right: You use D-72 stock to develop prints, returning it to the bottle after use and use it for months at a time with good results?

If so, and this works well, I have to do a couple of things. First is to apologize to the OP for assuming he was making some kind of procedural error. It appears I need some educating here...

So, the second thing is to ask you to elaborate on the practice and maybe compare it with the conventional method of diluting and using print developer for a session or two, either till it is exhausted or oxidized to the point of losing activity. Thoughts about throughput, capacity and shelf-life would be welcome.

FWIW, I'm using either D-72 or (more often now) ID-62 these days. I mix a working solution according to the directions (1+2 from stock for D72, 1+3 from stock for ID-62) and use it till it starts to degrade for whatever reason. These days, I'm spending 4-5 hours a day printing. A working solution of ID-62 lasts three, maybe four sessions when stored in a mostly-full bottle between sessions. I discard when oxidation starts to slow it down, but before the blacks in the prints are affected adversely (just longer developing times). D-72 behaves similarly, with maybe a bit less longevity.

TIA,

Doremus

Dektol is quite robust.

I’d say, out of solid experience (yes, 20 years and many thousands of prints, with more than a thousand just in the past 2 months) that you can reuse the 1+2 solution (if it’s back into the bottle after each session) for about a week, or 40 8x10 per Liter capacity, whichever comes first.

all I’m saying is that from experience, it shall last about a week. Discard as soon as you’re unhappy with blacks.

Rudeofus said:

Dektol, or at least what has been published as D-72 on digitaltruth.com, is my goto developer in a dark room I share with a few analog enthusiasts in my town. We typically meet once a week and run anywhere from 10 to 40 sheets.

We typically start with 2 liters of freshly mixed developer, and since dry paper soaks up developer and carries it into the stop bath, the amount of developer goes down over time. As a result, I have to mix a new batch every couple of months, and in times of lower throughput I sometimes mixed just one liter to top off the canister. I have not seen this developer going weak or inactive in all those years, except for periods of very low use, where a batch would sit around for >6 months.

In order for this to work you must not dilute the developer. Concentrated solutions dissolve less Oxygen, therefore Dektol stock lasts much longer than diluted working solutions. I have never had a problem developing prints in stock solution.

Click to expand...

There's two versions of the Dektol/D72 formula, the one you link to is the more accurate Metric version, but Kodak also rounded the converted weights from US Avoirdupois up/down in amateur publications.

Personally I'd rather dilute fresh each time and will mix what I neend for a session, and that could be very little developer. But taht's teh way I prefer to work and it's been perfect for over 50 years

Ian

I reuse paper developer all the time. I mix up one liter of working solution and pour it back into a bottle when I’m done. I put inert gas in the bottle, too. Once a month I mix up 200ml of fresh working soliton and mix it in. I’ve been doing that for at least two years now. This is Neutol WA. Not sure if this will work for Dektol. But I’ll try it when I run out.

Doremus Scudder said:

So, the second thing is to ask you to elaborate on the practice and maybe compare it with the conventional method of diluting and using print developer for a session or two, either till it is exhausted or oxidized to the point of losing activity. Thoughts about throughput, capacity and shelf-life would be welcome.

Click to expand...

It all started during a time, when I was pretty much the only one using our dark room. There were some folks from the photo club coming in for a chat and some laughter, but I was the only analog photog back then in this club. Throughput was very low, and the practice of mixing 1-2 liters of Ilford PQ every week appeared wasteful to me. I knew from practical experience, that dilute developers made from liquid concentrates sometimes lasted less than a week. This is when I started looking at developers, which would last a lot longer as working solution. My first choice back then was Ansco 130. I would get 25 grams of Glycin and mix a fresh batch of Ansco 130, about 2.5 liters. Knowing, that concentrated solutions would last much longer than dilute solutions, I used the developer as stock solution. A batch of Asco 130 would last for about 6-9 months, then it would become very slow or ineffective.

One day my ancient batch of Ansco 130 went bad and I had no Glycin, so I mixed a batch of D-72 following the metric digitaltruth recipe. This put me back in action, and I would simply observe, how long this batch would last. It turned out, that D-72 stock solution lasts just as well as Ansco 130. In the mean time more people started showing up with their negatives, so throughput went up. Currently a two liter batch of D-72/Dektol runs down to one liter (due to carry over) within two or three months, at which point I simply replenish with one liter of fresh D-72. This process has given me consistently good results for the last few years, there is no magic involved in this. I do mix my D-72 from cheap raw chems of, let's say, unspecified purity, my stashes of Metol and HQ are both multiple years old, both started out as medium gray powders and were kept in a cool but damp basement. My Carbonate, Sulfite and Bromide stashes are of better quality, and I follow the recipe to the letter, no sequestering agent added. The developer is dark brown, but as effective as it was on day one.

Average throughput right now is about 20 sheets of 8x10" RC paper per week, and developer capacity is mostly limited by developer carryover into the stop bath tray. We use mostly Fomaspeed Variant, sometimes Ilford RC MGIV, with the rare sheet of Ilford FB MGWT thrown into the mix. All these papers show very little variation with different developers, and I get very consistent results regardless of the age of my developer batch. I am aware, that some other papers are more sensitive to developer variations, these papers may show differences over time.

Effectively, then, you're replenishing D-72 stock with its own stock solution. Very economical, and surprising (to me) that it works well. I wouldn't have expected this.

If you always develop to completion, you'll see a lot less variation in the effect of old or partially exhausted developer -- if you develop by time, on the other hand, you'll notice changes as the developer weakens (even as it reduces in volume from carry-over), and then again when you replenish.

If it works for you, though, then it works.

I do develop to completion, yes. Or at least until there is no observable change in the images. I already stated, that the papers I use very much favor this mode of operation, and that my way of using D-72 may not give consistent results for people with finicky papers.

ericdan said:

I reuse paper developer all the time. I mix up one liter of working solution and pour it back into a bottle when I’m done. I put inert gas in the bottle, too. Once a month I mix up 200ml of fresh working soliton and mix it in. I’ve been doing that for at least two years now. This is Neutol WA. Not sure if this will work for Dektol. But I’ll try it when I run out.

Click to expand...

What inert gas do you use? A truly inert gas, like argon, or something which wouldn't react with the developer, perhaps nitrogen? Any suggestions for readily available gasses??

GRHazelton said:

What inert gas do you use? A truly inert gas, like argon, or something which wouldn't react with the developer, perhaps nitrogen? Any suggestions for readily available gasses??

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Cheapest solution is store brand butane lighter fuel. Heavier than air, blankets oxygen, and won't react with developer.

NOTE: do not use in a candle-lit period-correct wet plate darkroom!

Rudi,

Thanks for your explanation. It seems that your method of using stock D-72 and replenishing works well for low-volume use and should be the answer to the OP's question. I've never used the stock concentrate for regular print development, just for those times when I'm trying to eke out a bit more contrast from a graded paper (less often these days...).

It seems that the higher sulfite concentration in the stock solution works well to counter the effects of oxidation on the developing agents until the next replenishment. The things that do get oxidized aren't enough to weaken the developer appreciably, just darken it, and the replenishment happens often enough to keep activity constant enough for your papers and times. If I ever need to work just a few prints a week, I may give this method a try. At the moment, my throughput for a printing session is often more than 20 11x14s per session.

Best from sunny Eugene, OR and keep healthy during the lockdown there.

Doremus

There is more than just the sulfite to protect the stock solution from oxidation:

1. Oxygen doesn't dissolve all that well in water, and if there are other compounds dissolved in water, Oxygen solubility will go way down. There's an online calculator to show this. As soon, as salinity reaches 100 (which equals 10% ions in water), Oxygen solubility goes down by quite a bit. D-72 stock salinity is somewhere between 120 and 130.
   
2. There is more sulfite and Metol/HQ to deal with, so more Oxygen is needed to deteriorate the same relative amount of development agent and sulfite.

Donald Qualls said:

Cheapest solution is store brand butane lighter fuel. Heavier than air, blankets oxygen, and won't react with developer.

NOTE: do not use in a candle-lit period-correct wet plate darkroom!

Click to expand...

There's also this.
https://www.freestylephoto.biz/105193-Tetenal-Protectan-Spray-400ml

GRHazelton said:

What inert gas do you use? A truly inert gas, like argon, or something which wouldn't react with the developer, perhaps nitrogen? Any suggestions for readily available gasses??

Click to expand...

I just use wine preserver gas. It’s a mixture but mainly argon.