What's the use of stock solution?

hadeer · Jun 24, 2008

I develop my films in D-76H, for which I prepare a stock solution of 1 ltre a time. I dissolve the chemicals in water of 50°C (122°F). That gives me 4 shots of a 1:1 working solution. The problem with this method is that you have to cool down or heat up the prepared working solution every time you use it because the tap water is seldom the right temperature so as to end up with 20°C (68°F).
I wondered whether it would be feasible to keep the chemicals premixed in dry form (just as the Kodak D-76) and weigh off the right portion for 1 shot of 1:1 working solution every time I need to develop a film. That would give me a fresh working solution of the right temperature every time, plus it avoids the risk of storage detoriation of the stock solution in bottles that are only half full.
Another possiblity would be to prepare two to four (full) 0,5 ltre bottles with a 1:1 working solution and use them as needed.
Has anybody experience with this way of working? Would there be negative effects on the mix of chemicals? I would guess not as Kodak does exactly the same in their commercial packaging.
Thanks for any thoughts on this point.
Hans

RobC · Jun 24, 2008

No you can't split the dry chemicals. Dry chemicals don't mix evenly like chemicals dissolved in liquid do, so you cannot guarantee equal parts of each constituent when you split it. Only if each chemical were isolated could you do that.
You could always order the individual chemicals from the formulary and then only mix what you want.
Its actually more accurate measuring larger volumes of chemicals, so making up the stock solution and dividing that into 4 four bottles would give you the most consistent developer strength for each film development.

jim appleyard · Jun 24, 2008

I don't think you want to measure out small portions of an already mixed powder; you cannot guarantee that the proper amounts of each chem will be there.

For heating up solutions a microwave oven comes in very handy. For cooling, there are ice cubes, or better yet, take a couple of old plastic 35mm film holders,(the plastic thing that the 35mm cassette comes in) partially fill with water and then freeze. They do the same as ice cubes, but will not dilute your solution.

hadeer · Jun 24, 2008

jim appleyard said:
...you cannot guarantee that the proper amounts of each chem will be there.
For heating up solutions a microwave oven comes in very handy. For cooling, .... take a couple of old plastic 35mm film holders

I see the problem with the dry chemicals.
The suggestion to use frozen film holders looks very practical. (Now if I only can claim sufficient room in my wife's freezer.....).
Thanks Rob, Jim.
How about the idea of preparing several one shot 0,5 ltre bottles of working (1:1) solution? Would they be less stable than a stock solution in a bottle that might not be filled entirely after a certain amount of time (let's say 4-6 weeks)?
Hans

Colin Corneau · Jun 24, 2008

If you're worried about temperature, I buy a big jug of distilled water and keep it in the darkroom - when I mix up chemistry it's already at room temperature (20 degrees C) and ready to go...FWIW.

Monophoto · Jun 24, 2008

To cool down solutions, put some ice cubes in a plastic bag, and drop the bag into the solution. When done, store the plastic bag in the freezer.

I've used an immersion heater to quickly warm solutions.

But this issue is, for me, another argument in favor of HC-110 as my developer, especially in dilution H. Because the amount of stock solution required to produce a quantity of dilution H is rather small, the temperature of the stock solution isn't a major factor in determining the temperature of the working solution. It's relatively easy to fill a pitcher of water at a desired working temperature - just jockey the hot and cold to achieve the temperature you want. Then, the required amount of stock to a graduate, and then add water at the intended temperature to make the final working solution.

RobC · Jun 24, 2008

Its the volume of air that can oxidise the stock solution which is the major problem. If your storage bottles are full to brim then there is little if any air to oxidise the solution. So one bottle or four makes no difference if you don't get the air out. I use the collapsable bottles for stock. That way when I use some, I just compress the bottle to bring solution to brim and put top on. And keep it in fridge which reduces rate of oxidation.
Bringing to temp for developing is not a problem as I mix chems in a bottle with lid and drop it in a water resevoir at desired temp and leave it for ten minutes occasionally giving it a gentle shake( so as not to oxidise it rapidly).

HC110 is great stuff because it lasts for ages, doesn't seem to go off even in half full bottles and you can mix direct from syrup without first creating a stock solution. But you do need to be very accurate with measuring because such a small amount is used each time. A syringe is perfect for this.

jim appleyard · Jun 24, 2008

You can't store a 1+1 solution. Its life is only a few hours.

As said, HC-110 is a great dev. One reason is that the syrup lasts forever. I think Ilford makes an equivilent version. Rodinal is great for this, too.

bobwysiwyg · Jun 24, 2008

hadeer said:
I see the problem with the dry chemicals.
The suggestion to use frozen film holders looks very practical. (Now if I only can claim sufficient room in my wife's freezer.....).
Thanks Rob, Jim.
How about the idea of preparing several one shot 0,5 ltre bottles of working (1:1) solution? Would they be less stable than a stock solution in a bottle that might not be filled entirely after a certain amount of time (let's say 4-6 weeks)?
Hans

You can also use CoolBlues Reusable Ice Cubes. You can use them in drinks as well to get by the "freezer police."

RobC · Jun 24, 2008

jim appleyard said:
You can't store a 1+1 solution. Its life is only a few hours.

As said, HC-110 is a great dev. One reason is that the syrup lasts forever. I think Ilford makes an equivilent version. Rodinal is great for this, too.

I agree, storing working strength solution is not a good idea. It doesn't keep, except in a few cases where you use stock strength as working strength.

srs5694 · Jun 24, 2008

As others have said, storing working-strength film developer for any length of time is generally inadvisable. (How inadvisable depends on the developer.) It is possible, though, to store concentrate in one-shot quantities. For instance, if you use 250ml to develop a roll of film, you could measure out your stock solution into 125ml bottles. You'd then use one of these bottles plus an equal amount of water to mix your working solution. If you've got bottles that have slightly greater than 125ml capacity (say, 130ml), you could even "top up" to eliminate air in the bottle; up to a point, that might be preferable to keeping a more concentrated solution with an air gap in the bottle.

Concerning the temperature issue, there are time/temperature adjustment charts and tables available. These will tell you how to adjust for temperature deviations from 20 degrees C (or whatever you use as a standard) -- for instance, 8:30 at 20C is equivalent to 6:00 at 24C. I tend to use this method for small deviations in temperature, but beyond a few degrees I use hot or cold water baths.

Stephanie Brim · Jun 24, 2008

You know, I have an alternate experience with splitting a package of D76.

I did it because all I could find were the gallon packets and I really only needed a quart at a time. I shook the packet up well before I opened it, measured out the dry chemical into 4 equal amounts, and made up my quarts as needed. I tested, and times didn't differ from times on the Kodak website.

Then again, I'm often called a photographic nut case because I try everything.

nworth · Jun 24, 2008

Back to the point about storing the premixed ingredients in dry form, you can, but not like the powders you get from Kodak. The problem is that metol, unless specially treated, forms an insoluble adduct with sulfite. The way to get around this is to store the metol in one container and everything else in another, then be careful to dissolve the metol first. This is pretty impractical when you are mixing small quantities like one liter. Kodak used to sell small quantities of dry developer in sealed foil packets (and before that in glass ampules) before they discovered how to put everything in one bag, but you can't package things that way. There are other incompatibilities between the ingredients of other formulas that mean they can't just be all dumped in together, too.

Anscojohn · Jun 24, 2008

At the risk of beating a dead horse, your "problem" is just incredibly simple to solve. Make up a large amount of stock solution and store it in smaller bottles. At souping time, measure out the amount of stock you need. Take the temp. Get your diluting water about the same number of degrees above or below your needed developing temperature before you mix it with the stock. Your working solution should then be just about dead on. Use a water bath to hold it if necessary during the souping cycle.

gainer · Jun 24, 2008

I must have missed something. Did not Hadeer say he used D-76H? Does Kodak sell the kit to make that? IIRC, that is D-76 without hydroquinone.

I believe D-76 can be mixed twice as strong as standard, and stronger yet if part of the sulfite is left out. If necessary, the missing sulfite can be added to the working solution. I did some experiments once in which I reduced the amount of sulfite to as little as 1/8 the standard 100 g/l before a noticeable change in characteristics resulted.

You might find that PC-TEA will satisfy your needs. It can be used in various dilutions and the stock lasts a long time. If you have a "Thing" against Phenidone, you can use p-aminophenol base which is quite soluble in TEA or propylene glycol along with ascorbic acid and has, according to reports, characteristics similar to Metol. I'm just suggesting alternatives, not pushing. It's because I made my living as an aerospace engineer and had my fun (other than making kids) as a musician, an oboist at that. I was taught to spend part of my time trying new reed-making techniques. Now, the oboe is known as "the ill wind that nobody blows good" but I blew it good enough to be first chair in the Norfolk Symphony and the Governor's Palace Orchestra at Colonial Williamsburg. So I try new developers, etc., even while using the old ones for the occasional important photos.

dancqu · Jun 24, 2008

gainer said:
IIRC, that is D-76 without hydroquinone.

D-76H is a watered down D-23 with a pinch
of borax. With all that sulfite and little metol
it should be great for Smooth grain.

BTW that pinch of borax serves no purpose
in the absence of hydroquinone. Who came
up with that one? Dan

gainer · Jun 24, 2008

Maybe it was added on the theory it would keep the developer pH more constant during development. I think it was originally D-76 that someone left the hydroquinone out of. If it had started life as D-23, it would have no borax. A lot of people just change things to see what will happen and make up a theory if it does. Of course, I would NEVER do such a thing.

Lee L · Jun 24, 2008

dancqu said:
D-76H is a watered down D-23 with a pinch
of borax. With all that sulfite and little metol
it should be great for Smooth grain.

BTW that pinch of borax serves no purpose
in the absence of hydroquinone. Who came
up with that one? Dan

Grant Haist, the H in D76H, according to Anchell and Troop. The borax is there to retain working properties equivalent to D76. (p. 42, The Film Developing Cookbook)

Lee

dancqu · Jun 25, 2008

Lee L said:
The borax is there to retain working properties equivalent
to D76. (p. 42, The Film Developing Cookbook) Lee

So D-76H equals D-76 but is minus the regeneration
provided by hydroquinone. Some one must have
run out of hydroquinone. Dan

Lee L · Jun 25, 2008

dancqu said:
So D-76H equals D-76 but is minus the regeneration
provided by hydroquinone. Some one must have run out of hydroquinone. Dan

The problem was with fresh D76 having a pH of 8.3, at which point the hydroquinone is essentially inactive. Over a few months the pH rises, to up to 9, activating the hydroquinone. This was discovered a couple of years after the introduction of D76. With time, the original D76 formula changes character and becomes a hotter developer. Haist's solution to this problem was to drop the hydroquinone and increase either metol or borax by half a gram/liter, which gives working properties indistinguishable from the original formula without the inconsistent behavior. So it's more a case of "losing" the hydroquinone as opposed to running out.

Others have reformulated D76 in other ways to try and make it more consistent over time, changing alkali and adding KBr. Anchell and Troop report that these versions aren't as true to the original formula's characteristics as Haist's revision.

Lee

hka · Jun 25, 2008

The problem with leaving the HQ out of the D76 is the short selflife of the stock solution.
Within a month or 2 the developer is more or less inactive.
That's why I mix up small badges of it to avoid this problem.

hadeer · Jun 25, 2008

srs5694 said:
Concerning the temperature issue, there are time/temperature adjustment charts and tables available. These will tell you how to adjust for temperature deviations from 20 degrees C (or whatever you use as a standard) -- for instance, 8:30 at 20C is equivalent to 6:00 at 24C. I tend to use this method for small deviations in temperature, but beyond a few degrees I use hot or cold water baths.

I used to do this, but I now standardize on 20°C as I feel that this just eliminates one more variable in the process. I imagine that I have more consistant results now.

hadeer · Jun 25, 2008

gainer said:
...... Did not Hadeer say he used D-76H? Does Kodak sell the kit to make that? IIRC, that is D-76 without hydroquinone.....

Gainer, that's right, I use D-76-H which I mix from bulk chemicals. (Grant Haist formulas) There's no hydroquinone in the formula. I have tested the mix at different ISO speeds to determine the right film sensitivity and I see virtually no or very little difference with the Kodak commercial packaging. For me it works reliable and economically as well.
Hans

hadeer · Jun 25, 2008

hka said:
The problem with leaving the HQ out of the D76 is the short selflife of the stock solution.
Within a month or 2 the developer is more or less inactive.
That's why I mix up small badges of it to avoid this problem.

Harry, That's one of the reasons I switched to mixing from bulk chemicals. If necessary I make a one shot working solution for the occasion. No more dilemma's like 'Should I throw away this bottle or not...?' when returning home from a long trip or picking up darkroom activities after a hot summer month.
Hans

hadeer · Jun 25, 2008

Stephanie Brim said:
You know, I have an alternate experience with splitting a package of D76.

I did it because all I could find were the gallon packets and I really only needed a quart at a time. I shook the packet up well before I opened it, measured out the dry chemical into 4 equal amounts, and made up my quarts as needed. I tested, and times didn't differ from times on the Kodak website.

Then again, I'm often called a photographic nut case because I try everything.

Hi Stephanie,
I used to do this before I switched to mixing bulk chemicals. Worked like a charm, even with quantities for just one film. This is what triggered my question to the forum in the first place, because I found it so convenient. But I can understand the risk mentioned above with stability and uneven mixed ingredient with the DIYS-method.
Hans

What's the use of stock solution?

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