Mixing up old (20 y/o+) D-76 from powder.

JLeichtPhoto · Oct 3, 2021

Hello all! I have enough powder D76 to mix up 5 gal. but I'm not even sure it's still working. It's been basement-stored for the last 20 years, but wasn't opened until a couple summers ago when I checked to see if it had clumped or had any moisture in it at all. It's currently still in the basement, and to my knowledge has no moisture in it. If I wanted to mix up enough for one roll of 35mm in a Paterson tank to test it still works, what amount of the powder would I need to mix into the water? What ratio? Thanks in advance!

Paul Howell · Oct 3, 2021

That diffluent to do, either in cans or bags the dry chemicals can separate and using enough for a single roll you run the risk of not having a sample that has the right amount of each ingredient. As the question is "still good" I would mix the entire batch, test and if good use within 6 months or so.

MattKing · Oct 3, 2021

What Paul Howell said.
And I know, 5 gallons of D-76 is a lot of D-76.
Opening it two summers ago may mean it is now toast.

Nicholas Lindan · Oct 3, 2021

Powder mixing in Kodak chemicals is pretty good. They went to great pains to get the crystals of the various components all the same size.

I have experience in mixing up batches of powder for the medical industry. It really isn't that hard. The chemicals are all dumped into a large funnel shaped vat and stirred together. The resulting mixture is dispensed from the vat into vials. Dust is the big problem.

If the can was opened several years ago and then kept in the basement I can't say my prognosis would be good. If the powder is white and free flowing it is probably OK. The formula for D-76 is published. You should be able to calculate the grams of dry mix to 8 oz of developer ratio.

pentaxuser · Oct 3, 2021

So I think,Nicholas, that you are saying that Kodak did a good enough job of mixing the chemicals that it is possible to make up small batches of powder into a smaller liquid quantity than the 5 gallons that the whole amount of powder could produce?

Is this "in theory" or have you done it successfully yourself? Can you say what the actual formula would be for say dividing the powder to make 5 gal into grammes to make say 500ml of liquid?

Thanks

pentaxuser

mshchem · Oct 3, 2021

mshchem · Oct 3, 2021

Powders can be divided, otherwise Kodak couldn't have made the stuff in the first place. Suffice it to say Kodak was about as good at what they did (do) as it got (gets)

cliveh · Oct 3, 2021

Don't divide it, just mix the whole lot up and store in an air proof container. It will be useable for about 2 years.

MattKing · Oct 3, 2021

mshchem said:
Powders can be divided, otherwise Kodak couldn't have made the stuff in the first place. Suffice it to say Kodak was about as good at what they did (do) as it got (gets)

In a lot of cases, the powders were actually mixed either in the bags themselves, or in a container immediately before filling the bags. So there is absolutely no guarantee of homogeneity - particularly in a package designed to make 5 gallons of stock developer.

AgX · Oct 3, 2021

mshchem said:
Powders can be divided, otherwise Kodak couldn't have made the stuff in the first place.

But Kodak made their blends from pure ingredients, not from already blended stuff.

Thus Pentaxuser put up the crucial question, trickled by what Nicholas said: Did Kodak made blends with the intention of it getting parted for making smaller volumes of solution ?

To be fair, all classic washing powder is a blend to be parted for use. And basicallly, once a blend has been made, one may bind it so that all resulting particles are of, more or less, the same blend.

pentaxuser · Oct 3, 2021

I am being possibly premature in asking this question as Nicholas may not have had a chance to answer but has anyone tried mixing small quantities from larger quantities to make up, say, just enough to make 500ml or less? Was it successful and how did you then store the packs that were opened but still had lots of powder in them?

The danger here is that we get into an argument of two theories. One says that it cannot be successfully divided into smaller quantities and the other says that Kodak had the skill to mix it in such a way that it can be divided.

Actual user experience both good and bad is really what is needed

Thanks

pentaxuser

MattKing · Oct 3, 2021

If anyone has tried to ignore the manufacturer's recommendations in the way pantaxuser suggests, have you done accurate sensitometric tests to measure the difference (if any) in results?

Don_ih · Oct 3, 2021

I used to measure out small amounts of d76 to mix in 300ml of water. It worked fine. Any small difference in component chemicals from one amount to the next was not significant. The powder is obviously mixed thoroughly before being put in the envelopes. I don't do it anymore because I mix it from bulk chemicals.

Don_ih · Oct 3, 2021

Oh, and I wouldn't try it with Arista chemistry or Legacy Pro. Those powders are just not homogeneous enough.

Paul Howell · Oct 3, 2021

I've know of folks who have tired, mix results, some times spot on, sometimes close enough for government work, other times not at all, don't know how to predict. Considering the cost of film, maybe the cost of shooting a roll, why roll the dice, a gallon of Legacy Pro is 6.99, Ultrafine version of D76 is 5.49.

mshchem · Oct 3, 2021

MattKing said:
In a lot of cases, the powders were actually mixed either in the bags themselves, or in a container immediately before filling the bags. So there is absolutely no guarantee of homogeneity - particularly in a package designed to make 5 gallons of stock developer.

I disagree. I worked in the animal food and human food industries. As long as the particle sizes are close (you can't mix BBs and bowling balls) . We blended granular materials, medicated animal feed concentrates. Batch sizes ranging from 2,000 lbs to 40,000 lbs. This would be bagged, it was very consistent.

I worked in cereal plants, everything was blended and transferred in bulk throughout the operation.

I wouldn't waste my time trying to divide photo powders, waste of time and money. It can be done, if you follow a proven method.
Believe it or not.

gone · Oct 4, 2021

I've read of people dividing it up and using it one shot. It should be doable, but I'd use the old stuff from auctions in cans or pouches. That early D76 comes from the original Kodak company, not the new "improved" version. Whenever I've bought it this way, it's worked just like it should. If that old developer remains sealed, it might outlive even the youngest of us here.

Which is why powders can be a good thing, the convenience of liquid developer is weighed against the powders longer shelf life.

reddesert · Oct 4, 2021

JLeichtPhoto said:
Hello all! I have enough powder D76 to mix up 5 gal. but I'm not even sure it's still working. It's been basement-stored for the last 20 years, but wasn't opened until a couple summers ago when I checked to see if it had clumped or had any moisture in it at all.

Emphasis added. Developing agents are reducing agents, which means they can oxidize and become inactive, especially with exposure to air. Some developers keep well and some don't, and generally developers in sealed pouches keep well. But once it's opened then the clock is ticking.

The debate about whether you can mix a small portion of the package is legitimate, but that's a debate about whether the mixture will work optimally. I think you should mix a small portion of the package and test it on some film leader, because there's some possibility it won't work at all. It may have survived after two years open in powder form, but you just don't know.

MattKing · Oct 4, 2021

Here, as an example, is one mix yourself version of D-76.

I think most would agree that the Metol and Hydroquinone are both critical components, and that the relative proportions of Metol and Hydroquinone to the other components - particularly the Sodium Sulfite - is important.
The OP is starting out with a package that is 19 times larger than the recipe shown. The likelihood that a small portion of that much larger package will have, relatively speaking, the same proportion of components is quite small, no matter how much the package is shaken up beforehand.

Don_ih · Oct 4, 2021

It is virtually impossible that Kodak filled their various size packages of D76 in any way other than fully blending all the chemicals beforehand. Does anyone think they had someone measuring out exact amounts of individual chemicals to go into thousands of little bags, bigger bags, bigger cans, even bigger cans? No - they mixed a dumptruck load and then used that to fill envelopes, cans, and barrels.
Anyway, it does work to mix proportional amount.

RalphLambrecht · Oct 4, 2021

JLeichtPhoto said:
Hello all! I have enough powder D76 to mix up 5 gal. but I'm not even sure it's still working. It's been basement-stored for the last 20 years, but wasn't opened until a couple summers ago when I checked to see if it had clumped or had any moisture in it at all. It's currently still in the basement, and to my knowledge has no moisture in it. If I wanted to mix up enough for one roll of 35mm in a Paterson tank to test it still works, what amount of the powder would I need to mix into the water? What ratio? Thanks in advance!

It should tell you that right on the box.

Don_ih · Oct 4, 2021

Based on the current weight of a 3.8 litre envelope (415g), you need 54.6 g for 500 ml of stock solution. So, 27 grams will give you 500 ml of 1:1 solution.

Nicholas Lindan · Oct 4, 2021

Despite the hysteria, the folks who have worked in industrial compounding can attest that uniform powder mixtures are not a problem.

As to the criticality of developer formulas - if you are within 10% you are golden. Quantities like 100gm, 2gm and 5gm are a give-away. If it was a critical formula the quantities would be expressed with some precision as 89.7gm, 1.803gm and 5.34gm. When they are rounded to the nearest 25% the whole thing is pretty sloppy. Going through the evolution of formulae there are examples of 3 oz morphing into 100gm - a 10% increase and without a word spoken. Given the success of developing film in coffee and rosemary leaves (formula: 2 handfuls) I think we can all agree there is a lot of margin for error and most anything goes.

Worrying about things that don't really matter is comforting, I know - I do enough of it myself. So I guess the best advice about using small bits of powder from a large quantity of same is - if it feels right, do it. But don't post too much about it, it will just start a row.

mshchem · Oct 4, 2021

Don Heisz said:
It is virtually impossible that Kodak filled their various size packages of D76 in any way other than fully blending all the chemicals beforehand. Does anyone think they had someone measuring out exact amounts of individual chemicals to go into thousands of little bags, bigger bags, bigger cans, even bigger cans? No - they mixed a dumptruck load and then used that to fill envelopes, cans, and barrels.
Anyway, it does work to mix proportional amount.

Correct, but they use very sophisticated packaging equipment that keeps it from separating. Blending materials requires very uniform components. It's not difficult, if you can source or manufacture high quality ingredients.
I have a stash of 5lb bottles of Kodak sodium sulfite, the stuff is beautiful.
I would do one thing with a big old OPENED package of D76, THROW IT AWAY. Any old pouches of powder are suspect to begin with.
If one looks in the old text books there are methods listed for sampling ores, ground feeds, everything where you divide a pile. It's a pain not worth it.

I agree with Matt, keep the components separate and mix your own as needed. I've got Ohaus mechanical balances that I can weigh from 1mg up to 20 kg. No one want the old reliable mechanical balances, everyone is after the electronic cheapo Chinese junk.

MattKing · Oct 4, 2021

Don Heisz said:
Based on the current weight of a 3.8 litre envelope (415g), you need 54.6 g for 500 ml of stock solution. So, 27 grams will give you 500 ml of 1:1 solution.

And the OP's container has ~4,150 gm in it, so proceeding this way will mean you will be doing this 176 times.
The likelihood of the mixture being effectively the same (first to last) after that many iterations is not great.

Mixing up old (20 y/o+) D-76 from powder.

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