How many ML of D-76 powder do I mix with how many ML of water.

[Kirk Keyes]

An inert atmosphere not uncommon in industrial processes.

And not all that uncommon in the home darkroom. I and others use nitrogen to fill the Jobo tank when using developers like PMK. It's pretty cheap, once you set up the tank and regulator. And it works really well.

 

[Bob-D659]

At the moment I am using Argon, but will be buying nitrogen next, it's somewhat cheaper, and way more inert than the contents of other cylinders of welding gases I have. Works well for blowing the dust off of negatives as well.

 

[gainer]

Now tell me again why I cannot make my own D-76 from raw ingredients Metol, Hydroquinone, sodium sulfite and borax, using a set of measuring spoons, at a fraction of the cost and without whirly tumblers and nitrogen atmosphere. You see why Kodak would rather sell large packages of XTOL. The larger the sample, the less chance of deviation from norm. That is why we cannot recommend using part of a 5-liter package.

 

[Kirk Keyes]

Now tell me why you cannot make D-76 from raw ingredients; Metol, Hydroquinone, sodium sulfite and borax, using a set of measuring spoons for less than Kodak can on a commercial scale without whirly tumblers and nitrogen atmosphere.

What's your point?

 

[gainer]

Kirk, I didn't expect that kind of response from a person of your intelligence.

In 1973 I wrote about using the spoons in Petersen's Photographic and have been more or less derided ever since. The arguments against it are generally that we cannot be assured of getting the same weight in a spoonful every time. It turns out that for making a liter at a time, my approach might just be better than Kodak's.

Kodak appears to do on a larger scale just what we are told not to do for fear of getting a non-representative sample: mix part of a 5 liter package to make 1 liter. They can mix part of, say, a 500 liter package to get the 5 liter package they sell.

 

[skahde]

That is why we cannot recommend using part of a 5-liter package.

And it gets worse: XTol doesn't keep well once the original package is opened. Although I vacuum-sealed the smaller parts, after the first three batches convinced me of the inconsitency of the method, the remaining two became yellow and baked within half a year. Looked exactly like the baked 1L packages Kodak sold me back when XTol was released.
My partial packets Xtol kept worse than stock solution.

In a word: There simply is no point making partial packets from XTol.

best

Stefan

 

[Photo Engineer]

Patrick;

I have said before that Kodak mills to a common size particle as much as is possible and encapsulates some of the powders in coatings to prevent aerial oxidation. The packets are packed in an inert atmosphere. Without this the material would be an oxidized mass when you get it off the shelf.

Now, as to accuracy, that is done to better than 5%, probably closer to 1% on the scale that Kodak does it. We cannot do that with the raw chemicals that we buy due to the variations in size of crystals. I have posted here a weight/volume photo and comparison of 2 samples of KBr which vary in weight by 20% with the same volume. This would cause a serious problem in mixing a developer by using spoons. The sensitometry and sharpness alone would vary from the norm with these two KBr samples used in a B&W or color developer.

When I posted that, you compared your volumetric measure to reloading shells IIRC. Well, powder is extruded to an exact consistant size for just this purpose, and when you use a volumetric measure, you can cut grains to get a very precise measure. However, even so, precision shooters such as snipers hand load shells and do it by weight.

PE

 

[Kirk Keyes]

Kirk, I didn't expect that kind of response from a person of your intelligence.

Likewise, Pat.

They can mix part of, say, a 500 liter package to get the 5 liter package they sell.

PE has described the process that one needs to go to in order to insure uniformity when packaging large batches of dry chemicals. Your spoon comparison and assumptions of precision are simply not equitable.

 

[gainer]

But you missed part of my 1973 presentation. When you buy this KBr, for example, you usually pay for a certain total weight. The volume of that total weight in ml divided by 5 tells how many teaspoons are in that container. So what if it is different from the last you bought? Now, of course, you would be depending on the packager of the KBr to give you the weight you paid for if you did not have a means of weighing.

There is no question that the probable composition of a sample from any random mixture of solid particles varies with the size of the sample, no matter if the particles are uniform in weight and size. Suppose there are 4 substances required, as in D-76. There is a minimum number of particles that will have any chance of giving you D-76 when you dissolve them. That would be 109. The probability that any random sample of 109 particles will have the correct number of particles of each substance is practically nil. I suppose that there was a time when I could have calculated that probability, but that would have been at least 40 years ago.

The analogy with snipers or match shooters, as I once was, depends on the demands for accuracy being the same as for a photographic developer. That is not usually the case. I demonstrated in my original article that a deviation of 1/8 teaspoon plus or minus in the developing agents in 1 quart or liter of D-76 would not be noticed. I found that the variance in weight of 10 teaspoon measurements of any of the materials I used was much less than that.

The ten ring of a 50 ft 22 caliber match target is the size of the bullet. I could not have score 187 out of 200 possible in that Hearst Trophy match in St. Louis if the match ammunition had not been much better than I was. We fired single shot, gently pushing the cartridge into the chamber so as not to scrape any lead from the bullet. I tied for second place. I was 13 years old. The winner was a girl, and I shared second place with a girl.

I had no intention of suggesting that you should use spoon measurements in your lab work. Further, anyone who suffers from OCD would shudder at the thought. My disorder is the opposite. I like to see how far I can get from ideal and still make good pictures.

 

[Photo Engineer]

Patrick;

In a match shoot, the measure is quantitative. By that I mean that you can physically measure the deviation of any bullet hole from where it should be on the target. Included in this is the measure of distance from the target, of course, to insure that everyone is 50 ft from the target.

With photographic developers, this is also the case when you measure H&D curve, grain and sharpness.

For your article, did you do all 3 of the above or only eyeball prints? If you only qualitatively judged prints, this would be like using a pair of binoculars from 50 ft to look at the target and judge who won based on tiny positioning of groups. That would not be fair.

In our experiments we were required to do all of the above to get approval on a developer.

PE

 

[Kirk Keyes]

But you missed part of my 1973 presentation.

Actually, I have the Peterson's issue with your 1973 article around somewhere.

When you buy this KBr, for example, you usually pay for a certain total weight. The volume of that total weight in ml divided by 5 tells how many teaspoons are in that container. So what if it is different from the last you bought? Now, of course, you would be depending on the packager of the KBr to give you the weight you paid for if you did not have a means of weighing.

From what I can tell, NIST covers the methods and accuracy requirements for dry materials like powdered developers. See Fourth Edition NIST Handbook 133 (2005), Checking the Net Contents of Packaged Goods January 2005:
Dead Link Removed
Look in Chapter 2. As powdered developers are sold in seal containers, we don't need to worry about variation in wieght due to water uptake/loss.

The way I read this, we are to use the sampling plan in Table 2.1 for non-food consumer products. We could determine the maximum allowable variance (MAV) with 6 samples, and not have any significant correction to the variance that we measure. The number of Minus Package Errors Allowed to Exceed the MAV is zero.

Since our packages are labelled by weight, we then go to Table 2-5. Part B of Xtol, in the 5 litre size says it weighs 248 grams. For packages that range from 208 to 263 grams, NIST says that we can have a MAV of 12.7 grams. That works out to 5.1% MAV.

Now that said, those are appear to be the requirements laid out by NIST. Kodak may actually have a smaller MAV for their packaging requirements. And these requirements also do not cover the variation of the product contained in the package.

There's even a section on your old friend Borax there! (Section 2.4) You get a lot of allowance with Borax since NIST says it can loose up to 23% of its weight in moisture.

There is no question that the probable composition of a sample from any random mixture of solid particles varies with the size of the sample, no matter if the particles are uniform in weight and size. Suppose there are 4 substances required, as in D-76. There is a minimum number of particles that will have any chance of giving you D-76 when you dissolve them. That would be 109. The probability that any random sample of 109 particles will have the correct number of particles of each substance is practically nil. I suppose that there was a time when I could have calculated that probability, but that would have been at least 40 years ago.

I don't understand how you get "109" particles. Particles?? What?

I tied for second place. I was 13 years old. The winner was a girl, and I shared second place with a girl.

I hope the US Army hired them!

 

[Photo Engineer]

See my post in the color forum on hand mixing color developers. I have given several formulas that must be accurate to the milligram or tenths of a milligram level to give proper image quality. Same goes for pH. You can't get that with teaspoons and do an quantitative analysis of the results and come out looking good!

PE

 

[gainer]

I'll try to answer all at once. The statement was made earlier by PE that Kodak was working on ways to make particles of the various developer components of similar weight and whatever other qualities so there would be little or no differential settling. For the sake of argument, I ass-u-med that goal had been achieved. We have a mixture of particles of Metol, hydroquinone, sodium sulfite and borax that cannot be distinguished by weigh and volume. (I didn't say it was possible to do so.) Thus 2 particles of Metol, 5 particles of hydroquinone, 2 particles of borax and 100 particles of sodium sulfite are needed to make the smallest amount of D-76 that can be made from this fictitious mixture. What chance is there that 109 particles chosen at random from a batch that has some large multiple of 109 particles will make D-76? I think anyone would agree there is practically no chance.

How large a sample would be necessary to guarantee that 90% or more samples of that size would make D-76? I don't know, but a practising statistician might be able to say.

I never once suggested that color developer ingredients should or even could be measured by the spoonful. I will say that putting my faith in a well known commercial manufacturer of processing kits for color negative film didn't keep me from being screwed once. I had used some of the first chromogenic B&W film to take pictures of a concert of a Youth Orchestra. Bought the kit, used it exactly as per instructions, and got zilch.

We were all too young to join the U. S. Army. When I did join about 5 years later, my score with the Garand M1 was 185, enough to get me the expert medal. That was the last time I ever fired it. The war was over and my MOS was Topographic Computing in the Corps of Engineers.

Any way you choose to look at it, the probability of getting a representative sample of a large batch of developer or concrete or any other mixture of solids is greater the larger the sample.

 

[Photo Engineer]

Patrick;

Your assumptions are based on lack of understanding of materials science and manufaturing technology used in this particular field.

Actually, the HQ and Metol are encapsulated in a matrix of sulfite for extra protection. This along with other technical legerdemain leaves us with basically 2 or 3 particle types of equal size. It turns out that the models of rocks percolating to the top in shaken mixtures are based on equal density but different SIZE. This, I think, you missed in my original premise here.

However, results show that equal size and unequal density is also important. Therefore both are in play!

Thus the milled particles are made in the blending machine to have as close to the same density and size as possible, but to prevent problems they are constantly mixed and the package is intended to be used en-mass, not in bits and pieces.

Sodium Bromide batches come with different crystal sizes and crystal habits as do HQ and Metol. This is why using volumetric measure is difficult, as packing density varies by as much as 20%. If I cannot convince you of this, then I am truly sorry, but it is fact!

A gram of HQ = 1 gram of Sodium Sulfite ANH. This is a weight measure. But, the fluffy needles of HQ may occupy more than 2x the volume of the Sulfite therefore being even further outside of my 20% factor noted above.

PE

 

[gainer]

So, you are saying that two batches of KBr may have different weights per tsp without showing a difference in the volumes of the 100 grams I ordered from the two sources?

Where on earth would you get the idea that I said that a tsp of hydroquinone weighs the same as a tsp of Sodium Sulfite ANH? Any weights/tsp that I reported in 1973 were obtained by measuring and weighing 10 teaspoonfuls of the substance in question, 1 at a time, and using the average, and I reported also the variance of those measurements.

All measurements are subject to error. That is why someone invented the repeating theodolite for 1st order surveying. That is why the baseline length is measured many times with the tape under specified tension. If you are as wise to laboratory techniques as I think you are, you will repeat measurements numerous time, both to find if there is a variance and to use the RMS average.

Before you can know whether the variance of measurement is significant, you must know the variance in magnitude that can be tolerated by the system for which you are doing the measurement. In development of film, we may have both systematic and random errors of measurement of components of the developer, time and temperature of development, as well as errors in measuring the results. How precisely must we obtain the desired negative CI in order to make the print we want? How does that precision correlate with variations in the developer contents, time and temperature, phase of the moon, etc.

Whom do you know that looks at the first print off the perfect negative who does not say "Hmm. I think I might do a little better."? Does PE think "I measured the exposure, the film developer, ... everything that went into this print to the greatest possible precision. Therefore, this is the perfect print. Noone can do it any better."?

 

[Photo Engineer]

So, you are saying that two batches of KBr may have different weights per tsp without showing a difference in the volumes of the 100 grams I ordered from the two sources?

Where on earth would you get the idea that I said that a tsp of hydroquinone weighs the same as a tsp of Sodium Sulfite ANH?

With regard to the first paragraph, YES 1 kg of KBr may occupy a different volume and the same volume may have different weights. I showed this before and the variation I got with 2 samples of KBr was about 20% on average. I posted pictures of three crystal types from 3 bottles of KBr I have here. I include it again.

I never said that a tsp of HQ and Na2SO3 had the same weight and I never said you did. I used that to illustrate that they do NOT and that is the problem. Even the same chemical in two different crystal habits have different volumes or weights, depending.

Attached photo left, small KBr crystals, middle cubic large KBr crystals and right, fine powder KBr. Total variation on average samples measuring weight vs volume is +/- 20%. Therefore if the aim was 2.0 grams, the variation using volumetric measure could be as much as 1.6 - 2.4 grams. The difficulty of smoothing out the teaspoon measure of the coarser crystals compounded the error.

Sorry for the quality of the image, but that is digital for you!

PE

 

[gainer]

My point was that as soon as you receive shipment of a particular weight of any given powdered substance, you can measure the volume of that shipment and tell immediately if it is more or less "dense" than the previous shipment, and can convert the volume to units of standard teaspoons or measuring cups. Whether the accuracy of using volumetric units is sufficient for practical use is another matter. Kodak said long ago that if you want to weigh and mix developers you should have a scale or balance with a resolution of 0.1 gram. The recipes referred to were usually to make 1 quart.

You don't have to prove to me that volumetric measurements have a greater variance than your lab balance measurements. What you should prove is that the variance in performance of the developers made with volumetric measurements of ingredients is intolerable for practical photography. I tried to do that in my original article and failed. Now if I had been trying to use the spoons in a comparison test of two different developers, I would not have printed the results, nor would I personally have used the results myself without knowing the tolerance of each formula for measurement errors. That information BTW should be posted along with any new formula.

 

[Photo Engineer]

Patrick;

I agree with what you say on the face of it, but consider this....

You are therefore making what would be a simple problem of weighing out the ingredients for a developer into a continuing calibration and recalibration of the methods you use, keeping track of the weight/volume parameters of every chemical or batch of chemical. This turns lab work into a nightmare, but seems, at first glance, to simplifiy it when it in fact does not. It also introduces more error. For one example, it is impossible to take the coarse grained KBr and get a level teaspoonfull.

If you wish to solve the problem, you need a pharmacists ceramic mortar and pestle to grind all materials to a common size at least. Then the problem with varying crystal habit is at least minimized. You would still have to keep a complex chart of teaspoon = gram equivalents for every darkroom chemical, but at least not one for every batch.

PE

 

[gainer]

My original premise was that the usual amateur did not own anything better than a kitchen-type spring scale. I got my first one in 1973. I found it in my automobile under the seat. My thought was that some hippie had hidden it there. I was hoping it was not one of my teenagers. I never asked. I had been mixing my own developers by the spoonful, but they were my own concoctions, not attempts to copy D-76. Well, maybe a little D-23 now and then. When I came upon this balance, I started weighing my spoonfuls so I could tell those who had balances how to use my formulas without hearing them make fun of my spoon measures.

 

[Photo Engineer]

Well, Patrick, lets agree to disagree.

Ron

 

[monkeykoder]

I think the argument is if you don't have the equipment to mix their own but want to try it out. I may be wrong though.

 

[Kirk Keyes]

I can't stand working with english measurements for volume. If I had to figure out I needed 4 Tsp and 1 tsp and 1/4 tsp to measure something out, I would go mad. But if all I need to do is measure 25g of something, well, that's a lot more straightforward to me.

Also, it seems that if I have a scale/balance to measure the entire contents of my 1 lb bottle ( because we evidently can't really trust the bottle to accurately contain 1 lb of whatever is in it) then I might as well just measure out the stuff on my scale/balance. Why add an extra step?

 

[Ian Grant]

I can't stand working with english measurements for volume. If I had to figure out I needed 4 Tsp and 1 tsp and 1/4 tsp to measure something out, I would go mad. But if all I need to do is measure 25g of something, well, that's a lot more straightforward to me.

US weights and measures are just as bad, the tea-spoon method is also US. Thanks to the French we have the far easier Metric system, which is now International.

Ian

 

[eddym]

Note to OP:
Use HC110 instead. You can mix only as much as you need at any given moment, and the residual in the bottle will not go bad, and there will be no variability problem.

 

[Thanasis]

Note to OP:
Use HC110 instead. You can mix only as much as you need at any given moment, and the residual in the bottle will not go bad, and there will be no variability problem.

At the risk of sounding cynical, I can't believe it's taken 8 pages of posts to arrive at this. This thread is going on my ignore list and it's going on with extreme prejudice.