Maintaining Potassium Oxalate Developer Solution Over Time

[Neil Poulsen]

I recently purchased and have been reading Dick Arrantz's book on Pl and Pt Printing (2nd Ed.).

In this book, he states that developer is never discarded, that the age of his developer is 20 years. He recommends adding water when crystallization starts to appear.

While I find this interesting for an archival process, I like the environental implications. But versus watching for crystalization, what's a better way to monitor the health of this bath? For example, could one monitor pH and add water when the pH extends beyond predefined limits? Or, perhaps one could monitor density and add water when it goes out of range?

And, what about buffers or contaminates from countless sheets of paper entering this bath over time? Can their accumulation have negative consequences? I imagine such a bath eventually reaches some sort of equilibrium.

 

[sanking]

Bear in mind that each time you develop a print some of the developer is used up so in practice one must constanly add back to the main solution to top it off. I add back about 50ml of new solution for every 80-100 square inches of print development. So if you doing a lot of printing you will have replaced the entire contents of a liter of devleoper through topping it off.

Secondly, it is important to monitor the pH of the developer to make sure it stays acidic. As you run paper through the developer, especially papers that are a bit alkaline, the solution may become more base unless you take steps to counter it. I add oxalic acid to the solution to keep the pH at around 6.0.

From time to time I filter the solution.

That is about it.

Sandy

I recently purchased and have been reading Dick Arrantz's book on Pl and Pt Printing (2nd Ed.).

In this book, he states that developer is never discarded, that the age of his developer is 20 years. He recommends adding water when crystallization starts to appear.

While I find this interesting for an archival process, I like the environental implications. But versus watching for crystalization, what's a better way to monitor the health of this bath? For example, could one monitor pH and add water when the pH extends beyond predefined limits? Or, perhaps one could monitor density and add water when it goes out of range? Or both? When does one know to add more potassium oxalate?

And, what about buffers or contaminates from countless sheets of paper entering this bath over time? Can their accumulation have negative consequences? I imagine such a bath eventually reaches some sort of equilibrium.

 

[Michael Mutmansky]

Neil,

There are very few things that Dick had in either book that are incorrect. This is one that is true; the PO will be functional as long as it is not destroyed or lost. However, I disagree with Dick on this for a variety of reasons, not the least of which is the contaminants that you mention (which is quite considerable, especially if the developer is used warm or hot).

Plus, you ultimately do not know what the FO pt and/or pd salts, restrainers, and other hangers-on will do to your image. What I mean is, develop one in fresh developer, and then develop one in aged developer and you will probably see a difference. Can you quantify the difference? No. You only really know that the fres PO is fresh, and that is a somewhat repeatable starting point for future printing.

This is especially a problem if you use the dichromate method of contrast control, as I believe the dichromate becomes consumed somewhat, by the development, or possibly the buffers react with it, causing the contrast to drift a bit with continued use.

PO is not expensive if you mix it yourself, and it is not an environmentally harmful chemical that I'm aware of, so it makes sense to me to be more agressive about replenishment of the developer. It should help produce more consistant results in the long run.

The most important concern for maintaining the developer is the pH. There was a discussion about that recently here, but generally most people aim for about ph of 5 to 6. As the pH climbs, it becomes less effective as an initial clearing bath. As it crosses over to the basic side, it will actually hinder clearing by converting the FO into a less soluble version.

I us pH strips from Edmunds (100 strips for $1.00) to test. If it is above 6, I add a little oxalic acid to drop it down a bit.


---Michael

 

[photomc]

would like to add one more question to Neils excellent post....what is meant by "topping off" ? Do you add x amount of water, water + PO? Sorry, this is probably clear to everyone but me...I understand if you made up 1 liter of PO, after a period of use, it could be reduced down to say 950 ml, would you then add water back to equal 1 liter, or would you add 50 ml of water + x grams of PO?

TIA

 

[Mateo]

Another thing to think about is that as you print allot your developer will disapear. A dry peice of paper goes in the developer and then transfers to the clearing bath wet; you will lose some of your developer with each sheet. So replenishing is automatic by necessity. I don't use Dichromate and simply top off what I lose and the PH of my PO stays acidic. The PH strips are really good to have around.

 

[Mateo]

Mike,

The PO is pretty much a saturated solution at I think around 33%. If you lose 100ml just measure 33gm, mix it to make 100ml and add away. My method is allot more low tech and it works. If you use your developer real hot you'll be dealing with crystals all the time and figure out that the percentage of PO will almost automatically stay above the saturation point.

 

[sanking]

As indicated, I top off by adding back to the developer about 50ml of fresh solution for every 100 square inches of print development. I use dichromate control and add back the dichromate in the fresh solution in the same ratio as it is found in the main solution. For example, if the main solution contains 2ml of a 5% potassium dichromate solution per liter of solution, when I top it off with 100 ml of fresh solution I also add four drops potassum dichromate (where twenty drops = 1 ml).

Sandy

would like to add one more question to Neils excellent post....what is meant by "topping off" ? Do you add x amount of water, water + PO? Sorry, this is probably clear to everyone but me...I understand if you made up 1 liter of PO, after a period of use, it could be reduced down to say 950 ml, would you then add water back to equal 1 liter, or would you add 50 ml of water + x grams of PO?

TIA

 

[photomc]

Thanks Mateo and Sandy....that is Exactly what I needed.

 

[Neil Poulsen]

Contrast Agent

Out the starting gate, I purchased potassium chlorate from P.F. for my contrast agent. Does this have the same affect on the developer as the potassium dichromate?

Sandy, I just saw your second response. I'm not quite following when you say,

"I use dichromate control and add back the dichromate in the fresh solution in the same ratio as it is found in the main solution."

Is the "main solution" to which you refer the coating solution or the developer solution? My understanding is that potasium dichromate enters the developer through the print coating.

I like the idea of not tossing developing chemistry, just adding to it. I'm wondering about having a bottle of developer available for each paper so as to minimize the effect of one paper on the development of another, to avoid cross-contamination.

 

[sanking]

Neil,

I use the dichromate in the developer, not in the coating solution. What I am trying to convey is that I replenish the main solutin of developer with fresh solution that contains proprotially the same amount of dichromate.

Sandy

Out the starting gate, I purchased potassium chlorate from P.F. for my contrast agent. Does this have the same affect on the developer as the potassium dichromate?

Sandy, I just saw your second response. I'm not quite following when you say,

"I use dichromate control and add back the dichromate in the fresh solution in the same ratio as it is found in the main solution."

Is the "main solution" to which you refer the coating solution or the developer solution? My understanding is that potasium dichromate enters the developer through the print coating.

I like the idea of not tossing developing chemistry, just adding to it. I'm wondering about having a bottle of developer available for each paper so as to minimize the effect of one paper on the development of another, to avoid cross-contamination.

 

[Neil Poulsen]

I use the dichromate in the developer, not in the coating solution. What I am trying to convey is that I replenish the main solutin of developer with fresh solution that contains proprotially the same amount of dichromate.

Sandy, Is including dichromate in your developer part of your contrast control? What's your method of controlling contrast? Do you use any kind of contrast control agent in your coating, like with an "A" and a "B"? Thanks, Neil

 

[Michael Mutmansky]

Neil,

Most serious printers that I know use the dichromate contrast control method for reasons of consistancy and workflow. It is described in Dick's book somewhere, unless he took it out of the 2nd edition.

For the same reason, most serious printers will replenish their developer faster than minimally necessary. If you plan to make a print or two now and again, using old developer will work fine, as Sandy does it. If you want to be serious about pt/pd printing and desire the predictability and consistancy to make high quality prints efficiently, you will probably come around to a point where you are not using heavily aged PO.


---Michael

 

[sanking]

Neil,

Including dichromate in the developer is indeed part of my contrast control. I don't usually include anything in the coating, though from time to time I also use the Na2 method of contrast control, which does involve adding a bit of Na2 to the coating mixture.

You can follow the directions in Arentz' book for dichromate control, and by the way it works for pure palladium as well as Pt./Pd. I believe Dick mentioned somewhere that dichromate control would not work with palladium, but it sure does for me. BTW, any of the dichromates will work, though I believe Dick specifies sodium dichromate. My own system is based on adding very small quantities (2ml to 12 ml of a 5% potsssium dichromate solution per liter of developer). 2ml gives least contrast, 12ml gives greatest).

Sandy

Sandy, Is including dichromate in your developer part of your contrast control? What's your method of controlling contrast? Do you use any kind of contrast control agent in your coating, like with an "A" and a "B"? Thanks, Neil

 

[sanking]

Michael,

What is your replenishment system?

At my stated rate, which is 50ml of fresh solution of potassium oxalate for every 80-100 square inches of prints developed there is a 100% turn-over of all of the solution in a liter of developer for every 6-7 prints of 12X20 size. At this rate of replenishment I have not had any problem at all with consistency.

With kallitype, where I use sodium citrate, I must replenish at a much higher rate to avoid staining from ferrous build-up. In fact, my prefered way of working with kallitype is to just use the developer one-shot and then discard.


Sandy

Neil,

Most serious printers that I know use the dichromate contrast control method for reasons of consistancy and workflow. It is described in Dick's book somewhere, unless he took it out of the 2nd edition.

For the same reason, most serious printers will replenish their developer faster than minimally necessary. If you plan to make a print or two now and again, using old developer will work fine, as Sandy does it. If you want to be serious about pt/pd printing and desire the predictability and consistancy to make high quality prints efficiently, you will probably come around to a point where you are not using heavily aged PO.


---Michael

 

[Allen Friday]

Hello Neil,

Dick's book outlines three methods to control the contrast of platinum/palladium prints. He discusses each in the section on "Choose your method." The three methods are (using nontechnical terms) 1. The standard method. Use Ferric Ox. 1 + FO 2 in different proportions, the contrast agent is in the second bottle of FOS. By following the drop schedule for the two FOs, one can adjust the contrast of the print. The chart relates the platinum print to the paper grades on silver enlarging papers. In using this method, one uses a "straight developer", one with no contrast agent added. The problem with this method is that with flat negs, you have to use a lot of F02--which leads to all sorts of print problems like "grainy" prints.

2. The NA2 method. This is the method that Dick emphasizes in the second edition of the book. NA2 is combined with the FO1 to control contrast. The main benefit to this method is that one can print very high and low contrast images without the problems in the traditional method. It's particular benefit is that you can use a pure or very high palladium mix for the emulsion. This makes the prints very warm and very long scale. Palladiu is about 1/4 the cost of platinum. The down side is that you still have to mix the chemicals for each print. If you want to change contrast, you have to do a new batch of coating for the paper.

3. The contrast agent in the developer method. In this method, no FO2 or NA2 is used in the coating. The contrast agent, usually Sodium Dic. is added to the developer Pot. Ox. For example, to make developer solution #3, 4 drops of Sod. Dic. is added to each 200 ml. of developer. To make #4, 8 drops is added to each 200 ml. It is my understanding that this method only works with PO developer. I have not tried it with other developers. The down side to this method is that you have to keep a different bottle of solution for each contrast grade, up to eight different bottles. In practice, I only keep three bottles of developer, #3, 4 and 5. My negs generally print within that range, with most printing on #3.

Which method you choose is up to you. There are advantages and disadvantages to each method. Personally, I use the third method for most of my prints. The main advantage to me is it speeds up the test strip part of the process. When I print, I usually have a pretty good idea of which contrast level to start with. Using this method, I will often cut an exposed test print in half and develop one side at #3 and the other half at #4. I can then compare the two halfs side by side. Also, I can coat multiple peices of paper at the begining of a session and print different contrast negs just by changing developer.

If I have a very contrasty neg, which will not print on #3, I usually go with the NA2 method and straight PO developer.

Any of the methods can be used to make great looking prints. Which you choose should be based on your work flow, budget, and other variables particular to you.

One thing I do recommend is to keep the variables to a minimum when starting out. Decide if you like warm, neutral or cold prints. Pick an emulsion mix based on that choice, and then stick with it until you have printing with that mix down. Pick one developer, again based on print tone, and stick with it. Based on the above two choices, pick a method to control contrast and stick with it until you know its limitations. Once you have one method down, start playing.

 

[Michael Mutmansky]

Sandy,

I probably replenish at about 2X the rate you mention. I have noticed (especially with low amounts or restrainer) that there will be a bit of contrast drift in fairly short order, and it is very hard to maintian consistancy without dilligence.

You threw me a little by using the term 'topping off', because that implies that all you are doing is adding more developer to maintain a certain amount of solution. I generally will siphon off some developer every few prints and mix in some fresh. Typically, I'll pour off the top to keep, and the pour out the bottom where all the buffers and other contaminants have settled. Then, I'll replenish with fresh developer and add the dichromate needed.

I don't need to filter the solution this way, and even though I keep it hot, it is covered, and I rarely have any devloper drop crystals out when it gets cold. Ultimately, there is no reason to be working with the developer anywher near the saturation point. I mix mine to about a 20% solution.


---Michael

 

[EricNeilsen]

Michael,
Potassium Oxalate solutions that get too dilute can decrease printing speed and increase the grain of the print. At 20%, I'd only expect to see crystals form around the edges or top of your container.

 

[Michael Mutmansky]

Eric,

I mix to about 20% but I expect the developer is higher than that as I use it fairly warm most of the time. I figure that I replenish at 20% and the older developer is maybe getting up to 30% at most, and when mixed, it probably produces about a 25% mix or thereabout.

I haven't seen any speed loss using that approach, and I don't have problems with crystals, so I figure things are working fine. I used to use a more saturated developer, and I felt that having to deal with saturated solution was a hassle, so I backed off the mix a little. Works well for me, anyway.


---Michael