I got an early comment here on this blog, and I REALLY didn't want to get tangled up in some in-fighting at the time. Since that the same points have been raised several times, although later posts here, and the recent post by XXXX which also adresses the issue, I decided I will finally adress this and offer an explanation :
"Hello Eirik, one cannot stress enough that you first MUST determine the specific weights of the used ingredients. F.e. your 3-2-7 recipe translates to 8-1-10 for the kind of VC, soda and coffee I use. And what sense does it make to publish a recipe for 320 ml instead of 1 liter? I use 260 ml for my Jobo-tank, another one will use 250 and the next one will need 350 ml. Your x-y-z recipes always MUST include the amount of water, the millilitres your teaspoon eqals and the specific weight of the used soda, VC and coffee to be comparable and reproducible. Isn't that really confusing? I agree that you CAN measure by volume with sufficiant accuracy, but recipes basing on volume ALWAYS are unreliable if not declaring ALL these parameters. Best regards - Reinhold"
I'll address them point by point :
" one cannot stress enough that you first MUST determine the specific weights of the used ingredients"
Now, if one did read and understand what I wrote, all would be easy! Let me reiterate.
I have a set of standardised volumetric measures.
Whenever I contemplate to use them with anything I CALIBRATE them.
Calibrating is a simple enough process : if you measure out ONE measure you have a measurement error, typically up to a few percent. If you repeat measuring out and weigh and divide on how many measures is measured, you diminish that measurement error.
Statistical analysis will reveal easily enough that if you measure out 100 measures there will be *virtually no error*, and if you limit yourself to 10 measures the error will be reduced to a good deal less than 3 percent.
You now know how much a measure will hold. Since I'm after how much to put into solution, I paid little notice to specific weight, that is just an interesting tidbit of surplus information here.
But finding the specific weight is easy enough, since I know the volume each meassure will hold :
I simply take the weight in grams that each measure will hold of each type of chemical, and divide by the volume, translating to whatever units that might be interesting.
I weigh out 10 measures of Soda (anh.) and find the weight at 58,30 gram.
That means that each measure holds 5,83 gram ON AVERAGE, and that there is a good chance that this will be more than 97% accurate.
Since the measure in question was a teaspoon, marked 5 ml - which is the US standard for a teaspoon, the specific weight is arrived at this way :
5,83 gram / 5ml (5 cc) = 1,166 gram/cc. Simple and easy. But totally without interest to us - in this context.
What is important is that each measure will hold 5,83 gram ON AVERAGE, which means I need a little more than 9 measures per litre, i.e. ca 9,5 teaspoons per litre.
This is repeated for each type of chemical used and should need no further explanation, it is self-evident.
"F.e. your 3-2-7 recipe translates to 8-1-10 for the kind of VC, soda and coffee I use"
I'm perfectly fine with that, if that is your numbers, it reflects YOUR chemicals and YOUR volumetric meassures and how you calibrated yours.
AND EVERONE SHOULD UNDERSTAND FROM THIS THAT CALIBRATING THEIR OWN MEASURES IS THEIR OWN FRAKIN' RESPONSIBILITY!
But this does not mean I have confidence in your numbers - I think frankly you did something wrong along the way....
"And what sense does it make to publish a recipe for 320 ml instead of 1 liter? I use 260 ml for my Jobo-tank, another one will use 250 and the next one will need 350 ml."
Well in that case you need to work out how many teaspoons you need yourself, for your tanks and for each specific tank. I clearly stated I mix this for MY tanks which is an old JOBO and a Paterson System 4, one will need just 260 ml per 35mm film, the other 290 ml per 35mm film, mixing at 320 ml give me a small safety margin for both, and both will HOLD 320 ml. You do your math and adjust accordingly.
Your x-y-z recipes always MUST include the amount of water, the millilitres your teaspoon eqals and the specific weight of the used soda, VC and coffee to be comparable and reproducible.
Here our roads separate, you need not confuse anyone with specific weight, although it IS there, intrisic in the measurements, specific weight is what I really measure, I just don't confuse anyone with it.
I'm after the WEIGHT, the weight is the product of volume and specific weight. What is so hard to understand by that?
Since I know the volume of the measuring instrument, and state that CLEARLY :
1 teaspoon = 5 ml
1 tablespoon is 15 ml
1 pinch = 1/5 teaspoon = 1 ml
1/2 teaspoon = 2.5 ml
And the weight each measure gives from each type of chemical,
I can now measure out with great confidence the grams needed in order to get
54 gram soda
16 gram Vitamine C
40 gram instant coffe
Water 1000 ml
17.3 gram soda
5,1 gram Vit. C
12.8 gram inst. coffe
Water to 320 ml
And go on developing 35mm films in both my tanks with great confidence!
"I agree that you CAN measure by volume with sufficiant accuracy, but recipes basing on volume ALWAYS are unreliable if not declaring ALL these parameters. Best regards - Reinhold"
If you did care to read what I have stated several times I already and always DID declare all the parameters. Everything is in there, if you don't try to confuse people with unnecessary facts.
So what was all the fuss about, my friend?