Teaspoon measuring

[Photo Engineer]

You know, the late Barry Thornton put forth the "two teaspoons of sodium sulfite" theory of film developing. The very much alive Ken Lee put forth the "two teaspoons of sodium sulfite" hypo clearing theory.

I can measure two teaspoons consistently. I could also weigh two teaspoons of sodium sulfite on my OHAUS balance scale or my digital scale. Anyway you cut it, it's still two teaspoons.

Well, the answer is "that depends". You obviously don't know about my post showing 2 batches of KBr with 2 crystal habits, powder and cubic. There was a full 20% error between my two batches of KBr measured volumetrically.

This is the problem with those not knowing science or the scientific method.


PE

 

[richard ide]

Considering the variables that come in to play with photographic process steps and the extremely tight tolerances adhered to in the production of photographic materials; one must (should) do everything possible to eliminate as many of the variables possible. One has little control over exposure errors but a lot of control over chemistry, time, temperature etc. Having run about 10,000 control strips through my chemistry, I have a good understanding of what a small chemistry anomaly has in the quality of the finished product. Sometimes I would run several strips during one job. Obviously someone's standards are such that he feels comfortable with his measurement methods. I think that advocating these methods is (a serious) not a good idea. When you encounter a problem, you have no idea where the fault lies.
I remember photographing a document with a light blue image. I used old chemistry to develop the ortho film and got a perfect negative. I had a repeat order of similar documents and it was impossible to reproduce without using pan film which is a PITA. I have split packages of developer but only by quartering annd remixing several times to ensure a homogeneous batch.
Without consistancy your results are not consistant.

 

[sanking]

I really don't get it. The price of a good quality electronic balance is not that much more than the cost of spoons?

Why would anyone choose to handicap their work with imprecise measurements?

I hate to disagree with people whose opinion I respect, but my experience is that in many cases a difference of 0.2g in a developer formula of total of 1000 ml makes a big difference in results.

If you are on a desert island and have to do with lack of precision, ok, but with UPS, FED-EX, DHL and the USPS why do so if you live in the lower 48?

Sandy k ing

 

[David A. Goldfarb]

Even setting accuracy aside, I find it easier to measure things with a scale. It's easier to scale up or down a formula with measurements in grams than trying to figure out fractions of teaspoons.

It's true in the kitchen as well, especially baking. Modern cookbooks increasingly are listing ingredients by weight for both accuracy and easy scalability. Imagine if we were trying to measure sifted cups of sodium sulfite. At least with bread dough you can feel it and adjust the ratio of liquid to flour before baking it--in fact you have to because flour isn't a consistent product and ambient humidity is a factor--but it's much easier to develop a feel for this if you always start with the same proportions by weight.

 

[ntenny]

Now, tell me, what would you say in my place?

Though you weren't asking me, I think I've got an answer: I'd say pretty much what you're saying. The thing is, I'd have the same answer for Patrick Gainer if he asked that question.

As someone who lurks most of the time, and for whom much of the pleasure of analog is in messing around with darkroom processes, as an engineer by profession and a scientist by training, I really appreciate these discussions of process that you guys seem to have periodically. I've learned a lot from reading both of your posts, and tend to think that you're representing complementary approaches, both legitimate.

I have the impression you feel a bit ignored by the readership---a voice in the wilderness for a thorough understanding of process and tight quantitative methodology, while readers breeze past your stuff because it's difficult and run around looking for the easy answer. I can only speak for myself, but I think there are a lot of people in my position, reading your posts, thinking about them, taking things you've said into account while going about the business of turning photons into silver, but not necessarily posting about it.

Well, this is my post about it: I'm listening. Thanks.

But I still make Caffenol with volumetric measurements.

-NT

 

[Nicholas Lindan]

one must (should) do everything possible to eliminate as many of the variables possible

People shoot pictures with Holgas and Diana's because they don't know where the light leaks will be. They develop film in Coffee or use an unknown recipie from the internet just to see what happens. Adding uncontrolled variables is often considered a good thing.

Rather than try to do everything possible to eliminate variation I would rather say one should eliminate variables as needed - no more, no less - and that this requires a much deeper understanding of what is going on. To buy an analytical balance and weigh chemistry to the microgram takes nothing but time and money and any fool can waste both by doing so.

One begins to get a real handle on a process when one knows how much variation is acceptable. Then one can spend the time and effort concentrating on those things that really matter.

My experience testing B&W photographic materials and determining exposure requirements has shown me that the variation in the sensitive materials, agitation, temperature control, age of the developer and the water quality is much greater than any variation due to 'teaspoon measurements' when making up the developer - and that's for running film and paper through a sensitometer.

When it comes to taking pictures of real-world subjects and making prints that are subjectively pleasing - a teaspoon level of control is really more than is needed.

Volumetric measurement of dry powders is plenty Good Enough for black and white chemistry. A balance is needed, however, to calibrate the volume measurements - the 'gms/teaspoon' in the back of the darkroom cookbook is pretty approximate; powder 'density' varies with the size of the granules or crystals, and for crystals is dependent on the crystallization process. Some chemicals don't lend themselves to volume measurement - Kodak's P. Bromide that has the consistency of driveway gravel comes to mind.

Obviously, a commercial process will have a stricter level of control, as will color. But looking at the negatives that come out of the C-41 processor at Costco - flash pictures taken in Shae Stadium and the like - I'm not sure that it isn't largely wasted. I do, however, mourn for the very well run minilab at the now defunct local camera store.

 

[Curt]

and... sheesh! guys, the OP asked a simple question....and all but one jumped on him for measuring his chems with a teaspoon. Nice. What a nice bunch of helpful folks....

That being said, what is the op doing working with chemicals without a degree in chemistry in the first place?

By the way I was using this formula even with two electronic scales.



Amidol Teaspoon Formula

Water, 70º F
500 ml

Sodium sulfite, desicated
1 tablespoon

Amidol
1 teaspoon

Potassium bromide
1/8 teaspoon

Use full strength or 1:1. Often recommended for bromoil work.​

I had to make some calculated adjustments because I use it at 68 (little circle in the upper right corner of the 8 cause my keyboard doesn't have one or a cent sign), degrees. OK I add a little more Amidol, I've got plenty on hand.

I wonder if Edward Weston used Integral Calculus to figure the volume of fixer in the depression of his raincoat were fixer was held because he didn't have a fixer tray?

 

[alanrockwood]

Oh rats, I just composed a long and obviously brilliant comment for this thread. Then I pushed the wrong button and lost it!

 

[Curt]

Oh rats, I just composed a long and obviously brilliant comment for this thread. Then I pushed the wrong button and lost it!

That's OK, go ahead and redo it, we'll wait.

 

[Photo Engineer]

Though you weren't asking me, I think I've got an answer: I'd say pretty much what you're saying. The thing is, I'd have the same answer for Patrick Gainer if he asked that question.

As someone who lurks most of the time, and for whom much of the pleasure of analog is in messing around with darkroom processes, as an engineer by profession and a scientist by training, I really appreciate these discussions of process that you guys seem to have periodically. I've learned a lot from reading both of your posts, and tend to think that you're representing complementary approaches, both legitimate.

I have the impression you feel a bit ignored by the readership---a voice in the wilderness for a thorough understanding of process and tight quantitative methodology, while readers breeze past your stuff because it's difficult and run around looking for the easy answer. I can only speak for myself, but I think there are a lot of people in my position, reading your posts, thinking about them, taking things you've said into account while going about the business of turning photons into silver, but not necessarily posting about it.

Well, this is my post about it: I'm listening. Thanks.

But I still make Caffenol with volumetric measurements.

-NT

Thanks for the comments.

To start with, coffee is a very variable product in terms of photoactive ingredients and so making it with volumetric measurements is quite reasonable. There is a time and place for everything.

I guess there has been a history of bad science from a lab workers POV in many posts, and I have been trying to set the record straight as much as is possible. There are a lot of myths and misconceptions about mixing your own formulas, the most prevalent one being that you can get repeatable volumetric measurements. When I tried it in the lab with my 2 bottles of KBr, I got .8 - 1.2 grams of KBr for one measuring sequence, with repeats. This was worse than I had expected. So, I began this "crusade".

I'm sorry if it bothers people.

There have been a lot of posts on low quality films and papers recently. Well, this is what to expect with your developer if you use low quality measurments as well. Some companies apparently use the equivalent of kitchen chemistry to make products.

PE

 

[Bruce Watson]

Now, tell me, what would you say in my place?

PE

I'm not Brad, but I can answer that one. What you say, what you do, is tell the truth. A few of us will "get it" and most won't, or won't care. Such is life. You can't live other peoples' lives for them.

Remember what John Heywood wrote way back in 1546:

"A man maie well bring a horse to the water, But he can not make him drinke without he will."

Keep showing us to the water PE. Some of us are thirsty.

 

[Nicholas Lindan]

Nobody knows the truth.

All prophets are false.

-and-

The first words from the mouth of a pathological liar are "I never tell lies."

 

[alanrockwood]

Oh rats, I just composed a long and obviously brilliant comment for this thread. Then I pushed the wrong button and lost it!

OK, here goes again, not quite my original attempt to post, but covering some of the same issues. There are two key issues here: 1) What degree of trueness (i.e. accuracy plus precision) is required when measuring a given compound for a specific application, and 2) Is volume measurement adequate for achieving that level of trueness.

I would like to see the discussion (which pops up several times per year) focus on those two questions in a more realistic way. Let me list a few possible examples.

What degree of trueness is required for the measurement of metol for a single-component film developer? Can a volume measurement achieve it?

What degree of trueness is required for ascorbate for a two component film developer with a target concentration range for ascorbate in the saturation region with respect to superadditivity? Can a volume measurement achieve it?

What degree of trueness is required for potassium hydroxide when it is the sole activator in a developer? Can a volume measurement achieve it?

What degree if trueness is required for borax when it is the sole activator in a developer? Can a volume measurement acheive it?

What degree of trueness is required for the measurement of KBr when used in a film developer? Can a volume measurement achieve it?

What degree of trueness is required for the measurement of KBr for emulsion manufacture? Can a volume measurement achieve it?

Also, give some additional thought to the application. A print developer to be used in an amateur application with inspection-based development might not have the same requirement for trueness as a commercial film developer used in an automated film processor.

Underlying my series of questions above is the consideration of the purpose of the chemical and the sensitivity of the application to the concentration of the compound. For example the pH of a solution is more sensitive to the concentration of the activator if the solution is unbuffered (such as if potassium hydroxide is the sole activator used) than if the solution is buffered (such as if borax is used.)

 

[archphoto]

I think this is something for testing.
With volume measuring you will have a variable desity of cristals in a given volume.
So measure the weight of 10 volume samples and look how much it varies.

That variation should be taken into account to the above: is a 20% or 10% variation of each of the chemicals mentioned above noticable in the end result ?

By reasoning I think you will get more consistant results by measuring by weight than by volume, even if there are more variables into the play like the consistancy of your film/paper.

Peter

 

[fotch]

Absolutely. And there isn't an engineer who will tell you otherwise.

If the wood block needed to be more precise then the dimensions would be specified 12.0 x 12.0 x 12.0 and any dimension from 11.9 to 12.1 would be acceptable.

If you look at an engineering drawing you will find they all specify tolerances. Usually the tolerance is implied by the number of decimal places used in the dimension. If it is a critical dimension it may be specified as, say 12.354 -0.000/+0.001 inches. Any dimension without a tolerance is suspect.

What drawing? I know how to read a drawing and understand tolerance! The example given was used as given, nothing added or removed.

Would this not also apply to tablespoons? 2.0 vs. 2 tablespoons would be a large difference, would it not?

The argument that it doesn’t matter seems like an argument in favor of sloppiness.

As David Goldfarb stated, “Even setting accuracy aside, I find it easier to measure things with a scale. It's easier to scale up or down a formula with measurements in grams than trying to figure out fractions of teaspoons.”
I also think it is easier and more fool proof.

"I am one. Patrick Gainer is another." (Engineer)

Well, there are engineers and then there are engineers. The ability to communicate and be understood is more important. Stating exact specifications is a step in the right direction. Anything else leaves too much to chance.

 

[Photo Engineer]

Well, here is one of the problems. HQ is normally sold either as fine brown needles or as a fine brown powder. In one case, the HQ is in its native state as it crystallizes, (needles) but some companies grind it to a powder so they can ship it more compactly. The powder, weight for weight takes up less volume.

The same is true for KBR which is sold as cubic crystals or fine powder. Same reasoning as above. The powder is effectively more dense.

I have tested the KBr, as I have stated earlier, and found that 1 unit volume (any volume) can vary by over 20%. So, if you can stand that in your work, then by all means go for it. But, from a repeatability standpoint you could be adding anywhere from 0.8 to 1.2 g/l of KBr. This might work in Dektol, but would kill you in color work and would change many other formulas as well, in ways I cannot predict.

An added factor is the problem of leveling off a teaspoon full of fine powder vs needles or cubes. The cubes or needles are very difficult to level and this can vary in itself.

PE

 

[gainer]

I think this is something for testing.
With volume measuring you will have a variable desity of cristals in a given volume.
So measure the weight of 10 volume samples and look how much it varies.

That variation should be taken into account to the above: is a 20% or 10% variation of each of the chemicals mentioned above noticable in the end result ?

By reasoning I think you will get more consistant results by measuring by weight than by volume, even if there are more variables into the play like the consistancy of your film/paper.

Peter

If you can find it, read my article in Petersen's Photographic, April 1973 issue. I did exactly that. I discribed what I did in my recent post here in reply tp PE.

Borax is a point in question where measurement by weight is not reliable. There are two states of hydration: Pentahydrate and decahydrate. Both can and often do exist in the same batch. The best way to measure borax, even if it is reagent grade, is by volume of a saturated solution. A saturated solution at, say, 15 C will be equivalent to 3.79% by weight of the decahydrate, whether pentahydrate or decahydrate or a mixture went into the solution. The clear liquid of that solution, stored at a higher temperature, will remain at 3.79 weight percent and very nearly that same percentage by volume. If you feel compelled to weigh KBr eah time you use it, why not weigh it once to make a standard solution? Then the volume of a portion of that solution is as accurate a measure of KBr as you will be likely to need in ordinary photography.

 

[Chazzy]

Aren't teaspoon measurements perfectly appropriate for some applications, where exact measurements aren't critical? What if all I want to make is a citric acid stop bath?

 

[Photo Engineer]

Aren't teaspoon measurements perfectly appropriate for some applications, where exact measurements aren't critical? What if all I want to make is a citric acid stop bath?

That is reasonable.

PE

 

[Keith Tapscott.]

There are some good points mentioned in this thread as for practical ways of making processing solutions. For example, if making a fine-grain B&W developer where 100 grams per litre of sodium sulphite is typical for many formulas, then being a gram or two out would probably go unnoticed. However, with some components such as Phenidone or one of it`s derivatives, then being as little as 0.1 gram out would very likely make quite a significant difference to the activity of the developer. I think that being as accurate as practicable is a good thing to do.

 

[Nicholas Lindan]

KBr ... weigh it once to make a standard solution

I believe that is the standard practice: a standard solution. Also of Carbonate (for adding to print developer), Ferricyanide and Phenidone.

 

[Bruce Watson]

Aren't teaspoon measurements perfectly appropriate for some applications, where exact measurements aren't critical? What if all I want to make is a citric acid stop bath?

I don't even think it's appropriate for the kitchen anymore. I'm not a great cook by any means, but I've always had problems getting consistency from baked goods like cookies. Some batches are good, some are too sweet, some are too flat, etc...

Then I bought a kitchen scale. Suddenly I'm consistent. Turns out simple measurements like "a cup of flour" can be all over the map depending on who is dipping out the flour -- because flour can compress. As can brown sugar -- how packed is "packed?"

This is why kitchen scales are common in European kitchens. I'm still wondering why it took *me* so long to figure it out and do something about it. Sigh...

All that said, I still use teaspoons -- for liquids, where they work correctly.

 

[Nicholas Lindan]

I think you may be the only one making that argument.

Knowing how much is very important. That's why there is a tolerance on all quantities. The tolerance does not say "cut a bit of wood to 12.00 inches as best as you are able" - because, quite frankly, the person making the cut may not be able enough. Instead it says that in this application - a tooling fixture made of rock maple as an example - the length is only acceptable if the cut is between 11.99 and 12.01 inches. But if it is a bit of wood destined for propping the outhouse door then 12 inches plus-minus an inch is sufficient and someone making a cut to 1/100th of an inch would be considered touched by the sun.

The argument for specified tolerances is an argument for precision and is well beyond some exhortation to measure as best as you can. 'As best as you can' is just too damned sloppy a great deal of the time.

There are those of use who are convinced that B&W photographic chemistry tends to the outhouse-door-prop end of the tolerance spectrum.

Those who are convinced otherwise are under no compulsion to do other than measure out chemistry in any way they please. Ditto the teaspoon crowd.

A quick experiment - scooping 14 1tsp samples of of metol - shows a CV of 5% in the weight of the sample.

The effect of concentration on kinetics depends on many variables. See Mees revised edition, 1972, chapter 15. A general windage/rule of thumb is that development time for constant gamma varies 25% of the variation in developing agent concentration. Following this, a 5% error in developing agent would require a 1.2% change in developing time - for a typical 7 minute development that is equivalent to a time change of 5 seconds or a temperature shift of 0.25F.

 

[gainer]

I really don't get it. The price of a good quality electronic balance is not that much more than the cost of spoons?

Why would anyone choose to handicap their work with imprecise measurements?

I hate to disagree with people whose opinion I respect, but my experience is that in many cases a difference of 0.2g in a developer formula of total of 1000 ml makes a big difference in results.

If you are on a desert island and have to do with lack of precision, ok, but with UPS, FED-EX, DHL and the USPS why do so if you live in the lower 48?

Sandy k ing

Well, Sandy, you make stock solutions of your Pyrocat series and from there on it is volumetric measurements to make the working solution. You see the virtues of both. There are some chemicals that are best made into stock solutions. When you are working with developer stocks that are "put up" in glycerin or glycol or TEA, and have other stock solutions that contain the necessary alkali, you are well fixed to mix any combination of those to suit your fancy, if not your foreknowledge of the results. If you say to use 1 part A, 2 parts B and 100 parts water we know you have tested that combination. That doesn't keep us from wondering what would happen if we changed the numbers, and trying it out just for fun.

 

[gainer]

Well, here is one of the problems. HQ is normally sold either as fine brown needles or as a fine brown powder. In one case, the HQ is in its native state as it crystallizes, (needles) but some companies grind it to a powder so they can ship it more compactly. The powder, weight for weight takes up less volume.

The same is true for KBR which is sold as cubic crystals or fine powder. Same reasoning as above. The powder is effectively more dense.

I have tested the KBr, as I have stated earlier, and found that 1 unit volume (any volume) can vary by over 20%. So, if you can stand that in your work, then by all means go for it. But, from a repeatability standpoint you could be adding anywhere from 0.8 to 1.2 g/l of KBr. This might work in Dektol, but would kill you in color work and would change many other formulas as well, in ways I cannot predict.

An added factor is the problem of leveling off a teaspoon full of fine powder vs needles or cubes. The cubes or needles are very difficult to level and this can vary in itself.

PE

HQ is not a particularly good example for what I do with it. I have found that a wide variation in amount of HQ is tolerable in MQ or PQ developers where M or P are constant. The capacity of the developer is more determined by the Q, especially if the pH is buffered well.