Teaspoon measuring

[Nicholas Lindan]

12 literally means any number that round to 12 by standard rules for rounding, or greater than 11.5 and less than 12.5. If I want to specify 12 to the milligram, I say 12.000.

Here, here.

There is a tendency to anal retentivity in technical hobbies - and in all the wrong places.

With variations in scene contrast, uncontrolled lighting, shutters and apertures (how many here use T-Stops?) that are rarely better than 25% in accuracy, light meters that add their own 25%/1/4 stop error - and then add the variation in metering technique and a whole stop or two in preference in how dark a print should be made, and exposing at some 'personal ei' and mucking with developing times for 'N-1' and pulling an agitation regime from thin air - worrying about a gram or two of S. Sulfite makes no sense.

If you look at recipes for classic developers - as they came from the source - you will find many old formulas have been converted from ounces and grains to grams: an awful lot of things use multiples of 30 grams - meaning the original formulation was "Ah, heck, throw in 2 ounces and see how that works" - if it worked it got handed down as 60 grams. A recipe converted by an idiot will specify 56.7 gms - (N.B. the 60gm recipes are all 3.3010 gms in error). In real life any variation from 45 to 75 grams won't be noticed and might help. Weighing Sulfite out to 60.0 +/1 0.1 gram is most assuredly the wrong amount - as if it were to be titrated to the best value it would be a number like 67.3 gms, not 60 or 80 or 100. The one thing one can be sure about is that 60.0 gms is not the optimum value, it was just what worked well enough.

The sheet to sheet variation in paper speed and contrast is greater than any variation due to compounding developers with a teaspoon. Get thee a densitometer and weep.

Photography is an art. Touchy-feely is allowed. One doesn't need to buy a Holga to let go ... measure out chemicals by the 'pinch' or by pouring an amount into your hand - let the random element in without wasting $60 on a $10 toy.

If anyone wants to debate anal retentive credentials don't forget I'm the one here who advocates measuring enlarging exposure to 1/100th of a stop...

[gainer]

Patrick;

If I were to begin teaching a form of engineering, which from your POV was slapdash and inaccurate, I would imagine you would come down on me hard. Especially if we were both in similar teaching positions as we are on APUG. However, the reverse is now currently the case and I am stuck with you teaching what is from my POV, slapdash chemical techniques in the lab. They work, to an extent, but may fail.

IDK what to do. I am in a dilemma here. The more I argue for what is right from a scientific POV, the more you "disprove" me with your results which rarely have checks and balances. Of course, you will win because your way is cheaper and easier. Who wants to do it the hard way even if it is right?

So, ask yourself, is this the legacy you wish to pass on to future generations. I will be dammned before I pass on anything that is not right, procedurally or otherwise for lab work. And, I would not work in a chemical lab with you if someone paid me big bucks. I want to live! I think that you might be a hazard in the lab and your own kitchen.

Sorry for the rant, but remember that you are not a chemist and I am not a mechanical or aeronautical engineer. These fields are far apart. How would you like an orthopedic specialist in ankles and feet doing brain surgery on a loved one? I know. From your POV you would say "they are both surgeons". I cannot accpet that philosophy.

PE

If you and I were working side by side as research chemists, you and I would see things pretty much the same way. The only time I came close to injuring myself in analytical chemistry in college was the time I tried to blow some glacial acetic acid out of the jug after the lab assistant (who should have known better) filled the jug so that the blow tube was below the level of the acid. When I let up the pressure, I got a mouthful of the acid. That was VERY uncomfortable.

My career as aeronautical engineer was spent mostly in mathematical analysis of flight research data to obtain probable values of certain coefficients in the equations of motion by least-squares analysis. I learned a good bit about experimental error, both random and systematic.

I'm sorry, but I cannot see where anything I have written or taught, other than how to play the Oboe and make reeds for "The ill wind that nobody blows good", does anything but supplement what you teach, if indeed our paths even come close to crossing. I am not teaching Photo Lab, nor am I pretending to. You still have not read "Kitchen Tested Soups." I can tell. You do not realize that what I proposed was not slapdash, but was quite systematic. I did a sensitivity test on the main ingredients of D-76 to see how far off one could be and still get comparable results. I did a statistical analysis of weights of teaspoons of the commonly used chemicals. I described how to determine the weight per unit volume of bulk chemicals, and noted that these determinations should be repeated with each new batch. There were no cheap scales or balances in 1973 compared to the average wage.

Even if you have a scale or balance of sufficient accuracy and precision, the teaspoons help to use it by getting close to the desired weight. Why all the furor?

[Nicholas Lindan]

If I understand what you just said, for example, the engineer request from me a wood block, 12 inches by 12 inches by 12 inches, and I delivered a woodl block 11.5 inches by 12.5 inches by 11.90 inches, its OK?

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.

Ha, but then again, I am not an engineer.

I am one. Patrick Gainer is another.

Here is an engineering specification for the most bog-standard of all electronic components:

http://www.yageo.com/pdf/yageo/Leaded-R_CFR_2008.pdf

Notice that every number has a tolerance. Most of the data sheet is about how a 1K 5% resistor _isn't_ a 1K 5% resistor - initial tolerance, drift over time, drift with temperature, inductive effects ...

When a developer formula comes out with:

Metol 98%, <0.2% paraminophosphasomehingorother 12.3 gm +/ 0.15gm
S. Sulfite anhydrous, 90.60 · TC 42.6 ISO 418:2001 34 gm +/ 2.0 gm
Hydroquinone blahblahblah 2gm +/- 0.5gm

Then it is time to get out a balance and treat the numbers seriously. And the numbers won't come from chemists, but from chemical engineers. Until then it's all so much hot air.

[Venchka]

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.

[Photo Engineer]

Nicholas;

This:

"The sheet to sheet variation in paper speed and contrast is greater than any variation due to compounding developers with a teaspoon. Get thee a densitometer and weep."

Is simply not true!

A master roll of paper from Ilford, Kodak and Fuji must be within a tighter tolerance than you imagine. And to realize that, the developer mixing must be accurate.

I think that the post of the blocks of wood was very much to the point Patrick.

PE

[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