Teaspoon measuring

[archphoto]

Were measurements in teaspoons inacurate to begin with ?
I never understood that system anyway, it is like my coocking: a bit of this, a splash of that and no accarucy at all, not needed.

Would it not be wise just to weigh your chemicals in solid forms ?
In that way you have at least a standard and something you can repeat.

Keeping your chem's under a tight lid ofcourse in order to keep the water content as constant as posible.

Peter

[fotch]

I think the way PE is teaching is correct. If a recipe calls for 12 grams, it means 12 grams, not about 12 grams, or approximately 12 grams, or between 10 and 14 grams.

The more variables you induce, the harder it would be to find an error. Of course, it may work, just as an exposure is off a bit and the picture still is OK. Then again, maybe it isn't exactly what you expected, then tracking down the problem get harder with the more variables.

But then, what do I know. I just follow the instructions, seems much easier, at least for me.

[dancqu]

Hi all my chart does not include ammonium chloride or sodium
citrate does anyone out there have the gram equivalent data
for these chemicals i.e. grams/teaspoon ???? Thanks

I believe both chemicals have long term stability in solution.
So, as an alternative, mix up some easily weighable amounts
of each then dissolve in an appropriate amount of water.
Bottle then measure out the amount needed when
needed. Dan

[gainer]

Brad;

You are right.....

Of course, if we don't pass things on correctly to the following generations, they are doomed to doing it incorrectly and this level of accuracy will slowly degenerat. So, what would you do if you were me? Would you teach the wrong things? Give inaccurate formulas? I am trying to teach, and others seem to not care. This is a tough position to be in for me. Especially when Patrick says that "since 1973 the solution has given me the same activity" when in fact, he may be using the same batch of chemicals or he may not have made exact side-by-side comparisons. IDK.

If you use the same ingredients from the same bottle with the same crystal habit, this method will work, but if you change batches or crystal size or habit, then the volumetric measures can be off by 20%.

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

PE

I took your position in my previous post, and am certainly sympathetic. But I also took the position of the person who must make the results of the lab chemist practical as well as marketable. The results I spoke of getting with the simple volumetric measurements were from many different batches of Metol and carbonate. Ascorbic acid for use as Vitamin C has always been consistently 4 grams/tsp. It is that way because doses are prescribed in teaspoons or fractions thereof. The same goes for sodium bicarbonate. If I buy a pound of a chemical and trust the merchant to give me accurate weight, I can compute the weight of a fluid ounce or 30 ml or whatever volume from the measured volume of the pound I bought. I could as well measure the total weight, just to check up on my merchant, but I wouldn't have to measure it to the milligram.

I am not in your position. Neither are most of us who want to photograph something in B&W. I could not tell from the way one negative prints whether the developer I used to make it was exactly the same as the one I used to make another negative, even if the scenes were identical in everything but brightness range. Should I do the characteristic curve each time? How do I know that the film is not from different batches? There are and always have been ways to compensate for differences in film development during printing. My grandfather, who died in 1905, left a treasure of glass negatives, of which I have been able to print over 100 by various means. "By hook or by crook" as we old timers used to say.

[Photo Engineer]

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

[gainer]

I think the way PE is teaching is correct. If a recipe calls for 12 grams, it means 12 grams, not about 12 grams, or approximately 12 grams, or between 10 and 14 grams.


But then, what do I know. I just follow the instructions, seems much easier, at least for me.

According to standard engineering practise, 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.

[fotch]

Well, then we know why products sometimes are a real nightmare. I have a friend who is an engineer and sometimes I will make something out of wood per his design.

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?

As they say, size matters.

I could not build a house or a cabinet or a clock!

But you could build an airplane? There must be something being lost in the translation or I am never going to fly again.

I certainly am not trying to insult you but it just seems screwy to me. :o

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

[Photo Engineer]

Patrick;

I've been thinking about this and I have some additional thoughts.

In the few chemistry lab courses you took did they ever teach you to measure solids in spoonsful? Or, did they teach you to use weight? The use of volume to measure solids dates to the medieval alchemists who often did this, but the method was recognized for the unscientific method that it was, as scientists in general began adopting the scientific method.

If you realized that we experienced people are in a world wide classroom, and it behooves us to pass on the very best, then you might see things differently. We must teach the very best to those that follow or we will allow them to fall into error or allow them to fail utterly in keeping the legacy of analog photography alive.

I am totally frustrated at this moment, having been unsuccesful in convincing you that although your method may work, it may fail as well and it is the wrong thing to teach future generations. We have argued this on-line for quite some time and you are adamant.

My position is not adamantine in nature, but merely following the scientific method laid down many years ago as the medieveal scientists came out of that era, shrugged off the cloud of superstition and guesswork and adopted the right way of looking at the universe.

PE

[jim appleyard]

After reading all this, the OP has gone digital.

[Photo Engineer]

Nope, he moved to Photo Net.

However, Jim, having now chimed in...

What would you do if you were me?

I'm interested.

PE