Teaspoon measuring

[fotch]

You might try OCR that comes with some FAX programs and create text. Not fool proof, you may have to make some corrections to what the OCR produces.

 

[gainer]

I lent my copy to someone who never gave it back. Many, many things have happened meanwhile, including a move from Newport News, VA to Glenville, WV.

My use of teaspoon measures has been blown far out of proportion. I use them a lot for personal work where I know from experience that they are sufficient to the task at hand. I sometimes report formulas in terms of teaspoons where the only possible concern might be repeatability, but if one if one has a scale with the accuracy and precision that makes one's world go round and keeps one from having bad dreams, the teaspoons may be weighed as they are added so that if the formula works as I said it should, it can be repeated to the milligram. There are in fact some formulas that I would have to weigh in order to post them as weights.

 

[Kirk Keyes]

classic....the scientist vs the engineers.

For whatever it is worth any engineer worth his salt will immediately point out that a product or process that is not robust against minor variations is worthless...or simply put, un-economic, not feasible.

[...]

For the OP, I looked up the density of Ammonium cloride and found it to be, 1.5274 g/ml . I figure a standard teaspoon is 5ml so, I get 7.6 grams per teaspoon. In a similar fashion, I get 8.5 grams per teaspoon for sodium citrate.

For whatever it is worth, engineers ought to know the difference between "density" and "bulk density". I thought that was in the civil portion of your state engineer licensing exam...

Looking up the "density" is not the actual answer that the OP needs. What needs to be looked up is the "bulk density" of the material in question. The "density" tells you what a crystal of the material that is one centimeter cubed weighs, where as the bulk density of that material tells you what that material with a particular particle size and shape wieghs when stacked into a known volume.

Density doesn't account for the air that is included between the particles, and density doesn't account for the stacking/packing of the particles. The packing can be greatly affected by the size and shape of the particles. These variables can vary greatly depending on the source of the material. As PE demonstrated, he was able to get 20% variation just by comparing different bottles.

My bottle of stuff may be much different than your bottle of stuff.

 

[gainer]

You might try OCR that comes with some FAX programs and create text. Not fool proof, you may have to make some corrections to what the OCR produces.

I'd forgotten about that. I think my Word Perfect may have that facility. I'll look.

 

[Kirk Keyes]

To paraphrase all these 120+ posts, it seems that there a few points that could be made:

1) If repeatability in your process is important, then use a scale or balance. You can get better precision and accuracy by weighing ingredients than by measuring them by volume.

2) Formulas containing certain ingredients, like halides, should be weighed. Especially true if iodide is used.

3) Formulas with small amounts of any ingredient, less than a couple grams, should be weighed. Spoons are not really suitable for the small amounts often used in some developer formulas. Anything with phenidone, it's derivatives, and again, iodide, come to mind.

4) Formulas that have more than one developing agent should be weighed. Maintaining the balance/ratio of the developing agents will be more difficult when using spoons than by weighing.

5) If you are intent on using a particular formula, weigh the ingredients as listed. (If the formula gives directions in spoons, say with an amidol paper developer, then go ahead an use spoons. It's obviously not that critical for those formulae.)

6) Simple developers containing just a couple ingredients could be measured with spoons if the level of precision or accuracy is not important to the user.

7) Stop Baths, Fixers, and Washing Aids are generally simple enough that spoons could be a reasonable option. An exception should probably be if hardeners are incorporated.

8) Since B&W paper is generally developed to completion, it could be an option for some developers to use spoons.

9) If you want to use spoons, get a good balance and calibrate your spoons for each chemical that YOU have. Every time you get a new bottle, recheck the calibration of your spoons. As you work down to the bottom of the bottle (things sift out in bottles based on particle size/density), you may want to check things again.

10) Now that you have that balance that you used to calibrate your spoons with, you now have a balance that you can use when you need it.

There is no a priori way of knowing where the weights listed in a formula need to be precise and where they can be used with less accuracy. This knowledge can only be determined through testing.

Keep in mind that there is generally more at issue than simple solution "activity" when formulating a developer. A lot of balancing is put into the best formulas to achieve the desired properties of a particular developer. The best way to realize those properties is to weigh out the ingredients.

 

[Sirius Glass]

Thanks Kirk

Steve

 

[Clay2]

Good shot Gainer, Bulls-eye !

ROFLOL, HA! I said I love this thread!

Best regards,

/Clay

 

[gainer]

Kirk, I think you are obsessive-compusive about this. That is another way of saying you have traded common sense for uncomon nonsense.

Precision and accuracy are not always found together. Standard solutions are often used for keeping laboratory reagents. Some, like borax, have two or more hydration states that are mixed in the ostensibly dry state, yet a saturated solution has a solid content that depends only on temperature. Others are difficult to weigh accurately because of hygroscopicity. Phenidone is used in such small amounts that a 0.1 gram error is significant, but a 1% solution can be made in glycol or glycerine.

Where synergism between two agents is present, the activity of the pair approaches assymptotically a maximum. Adding more hydroquinone to the PQ or MQ pair after that peak has no practical effect except, perhaps, on the capacity of the solution.

We used a lot of strain gauges at NACA to measure wing shear and bending moment in flight. These had to be meticulously calibrated on the ground, but there were still shifts in flight, probably due to temperature differences between upper and lower wing surfaces, that seemed correlated to altitude. I spent hours trying to describe and "correct" in mathematical and physical terms these anomalies until our wise branch head (a typical New Englander) told me just to present the data. What am I saying here? We now have strain gauge scales with digital readout up the kazoo that seem to give us previously unheard of precision, but with possible consistent errors. That is why I suggested checking the accuracy and linearity of your digital scale by adding pennies one at a time.

I think that if the weight of any ingredient is critical, the originator should be responsible for showing that in the formula.

 

[fotch]

I think that if the weight of any ingredient is critical, the originator should be responsible for showing that in the formula.

Is that true? I mean, is that most uses of formula's would understand? I would think that the ingredients are stated to be an accurate amount and if it was not critical, should have a note saying something like "approximate" or "about", or "plus or minus x".

What comes to mind is Read the Instructions First.

I have never mix chemicals except when I was very young and with friends Chemical Kit, made some interesting things. My parents took away the Kit real quick, you might say in a flash of smoke.

 

[Kirk Keyes]

Pat - obsessive/compulsive? Compared to some of my co-workers, I'd have to say not. Concerned about sharing good working methods, definitely.

And I don't beleive in what's called "common sense". I think that's a term used to put a person down when they do something that they had no way of knowing would be bad. I have a three year old, and say she touches something that I know without thinking is hot, but to her, she has not learned how to tell when something is hot without touching it. Should I blame her for not knowing better - afterall, it's common sense not to touch something that's hot, or should I try to help her learn about hot and cold, and how to tell? Perhaps telling people that using spoons to volumetrically measure things and not telling them when it could be used with minimal issues vs. when it makes a difference is "uncommon nonsense"?

 

[Kirk Keyes]

Precision and accuracy are not always found together.
[...]
What am I saying here? We now have strain gauge scales with digital readout up the kazoo that seem to give us previously unheard of precision, but with possible consistent errors. That is why I suggested checking the accuracy and linearity of your digital scale by adding pennies one at a time.

Precision and accuracy may not always be found. But using spoons is not going to be a very good way to achieve them when they can be achieved together.

I have actually tested my two digital scales with a certified set of weights. That not only tells me about precision better than your pennies, but it also tells me about the accuracy of my scales. To my delight, my $20 digital scales were both within the display resolution for every certified weight I tested them with. I certainly did not expect that, but I'm delighted nonetheless about it!

And I wasn't being obsessive/complusive - I was merely being curious...

 

[Kirk Keyes]

I think that if the weight of any ingredient is critical, the originator should be responsible for showing that in the formula.

I'm with Fotch - He's got some good questions on that. But that also seems a bit impractical.

But, you know, I'm with you too. It would be great if the originator of any formula showed how much latitude and where it was in the measurements needed for any particular formula.

By the way - since I have you on the interweb here, I understand that you helped with the formulation of Pyrocat-MC. I understand that Pyrocat-MC gives higher accutance than Pyrocat-HD. I expect that if I deviate to far off the stated formula for Pyrocat-MC, that I'll loose that accutance advantage. What are the engineering tolerances that one needs to meet when preparing Pyrocat-MC? The formula lists the ingredients with one digit to the right of the decimal place for ascorbic acid and metol. I'm not sure, but does that mean I need to measure everything to +/- 0.05 g for those?

Also, the pyrocatechol says 50g. Engineering-wise, I should probably read that number with scientific notation to better determine how many digits I need to pay attention to. OK, so that means the pyrocatechol would be 5 x 10^1. I guess that means I can read that as 5 +/- 0.5 X 10^1. So anything I measure between 45 and 55 grams is fine, right. After all, we're just reading these things as an engineer should.

Maybe you could be kind enough to convert Pyrocat-MC to spoons for us? If I use spoons, can I be certain that I'll maintain the precision or accuracy needed? What if my stock chemicals have densities that differed from your stocks? Could you tell me how accutance varies if I'm low on the ascorbate and high on the metol and high or low on the pyrocatechol? Are any one of those critical? If so, which ones are critical? I'm sure you've got all that data ready to present to anyone that asks.

 

[mhcfires]

I have just spent the past hour or so reading all the posts in this thread. I want to thank everyone involved in this very interesting discussion about accuracy. My dear late wife was one of those people who used a scale to weigh everything in the kitchen. She was also an inveterate note taker and data collector. I guess a lot of it wore off on me. I tend to side with those who say "use a scale or balance", but the lazy side says to just spoon it out. I think that within reason everyone is right. When making a new lensboard for my Speed Graphic I used my neighbor's table saw. He is a machinist, everything he has is calibrated to within a gnat's eyeball. When setting up the rip fence on the saw, I measured to see if it was square, and it was within a 64th inch. I really didn't need that much precision, but when finished, the new board fit my camera better than the one that came with it.


Again, thanks to all who have helped me to greater appreciate photography. Now that I am nearly retired (working only 2 days/week) I can get out and start to wear out some of this camera gear that I keep on collecting. But then that is fodder for another forum in APUG.

 

[gainer]

I'm with Fotch - He's got some good questions on that. But that also seems a bit impractical.

But, you know, I'm with you too. It would be great if the originator of any formula showed how much latitude and where it was in the measurements needed for any particular formula.

By the way - since I have you on the interweb here, I understand that you helped with the formulation of Pyrocat-MC. I understand that Pyrocat-MC gives higher accutance than Pyrocat-HD. I expect that if I deviate to far off the stated formula for Pyrocat-MC, that I'll loose that accutance advantage. What are the engineering tolerances that one needs to meet when preparing Pyrocat-MC? The formula lists the ingredients with one digit to the right of the decimal place for ascorbic acid and metol. I'm not sure, but does that mean I need to measure everything to +/- 0.05 g for those?

.

My contribution to Pyrocat MC was in showing ways to get Metol to dissolve in Glycol, and pointing out that ascorbic acid can substitute for sulfite for the purpose of making Metol, p-aminophenol or Phenidone synergistic with catechol. The relative amounts are left to Sandy King's judgement. To the engineer, and I would hope to the scientist as well, 50 grams means any number that would round off to 50 by standard rules of rounding off. That would be a number that is greater than 49.5 and less than 50.5 for catechol and greater than 2.45 but less than 2.55 for Metol.. I did not test those limits. I showed Sandy how to make a secondary stock solution of metol and ascorbic acid in glycerol that is soluble in propylene glycol. 100 ml of this solution will provide 2.5 grams of Metol and the necessary amount of ascorbic acid to insure synergism between the Metol and the catechol.

Common sense would tell you that assumptions that one makes about the effects of varying amounts of any or all chemicals in a formula should be tested before they are presented as authoritative statements of fact.

 

[cmacd123]

I have actually tested my two digital scales with a certified set of weights. That not only tells me about precision better than your pennies, but it also tells me about the accuracy of my scales.

Don't be too quick to dismiss the use of coins as a way of checking a scale. Both American and Canadian coins are made to fairly tight tolerances. Whne I was a school kid years ago we got a trip to the mint and saw the fancy scales that hey used, with coins that were over or under weight going into scrap bins to be re-melted.

This in the US can calibrate your handy roll of unused quarters from the bank at this address.
http://www.usmint.gov/about_the_mint/index.cfm?flash=no&action=coin_specifications

or http://preview.tinyurl.com/2qtg3

(each US half dollar when new is 5.670g note the decimal places.)

If your bank sells you new Canadian coins you will have to look them up here:
http://www.mint.ca/store/mint/learn/circulation-currency-1100028
The Canadian quarter is currently 4.4g down from the 5.05 it used to be.

if you would rather use other values, the specs are all on the sites.

 

[Kirk Keyes]

http://www.usmint.gov/about_the_mint/index.cfm?flash=no&action=coin_specifications

or http://preview.tinyurl.com/2qtg3

(each US half dollar when new is 5.670g note the decimal places.)

Certainly, new coins can be used. I didn't say they couldn't. From the chart you link to, the penny at 2.500g and the nickel and 5.000 g look like good choices to use for this.

I also visited the Phillidelphia Mint, I think it was in 1977. It was certainly fascinating to see all that money moving through the Mint.

By the way, it appears that the weight you stated was for the US half dollar is actually for the quarter. The quarter weighs 5.670g, and the half dollar weighs 11.340g.

 

[sanking]

Don't be too quick to dismiss the use of coins as a way of checking a scale. Both American and Canadian coins are made to fairly tight tolerances.

Excellent point. I have made this test myself with comparison to the standard weights I own with my scales and you can bet your life on the fact that American coins (sorry, have not tested the Canadian ones) have very tight tolerances.

Let me say for the record that in the world of teaspoon and balance users, I am with the balance group. I actually own a scale that measures accurately to 0.01g, and use it a lot for my work.

But Pat is absolutely right in that this type of accuracy is not required for some work.

Let's try to keep ideology out of this, and avoid the personal insults.

Sandy King

 

[gainer]

I also use both. When I am designing some formula I may use the spoons from the start. When I find what works as desired, I can weigh the volumes that I used. Now there is no reason for me not to publish both measures. I know either will work as well as the other, whether or not the reader believes so.

I found a copy of the issue of Petersen's Photographic, April 1973, that contains "Kitchen Tested Soups" and when it arrives I will see if anyone in APUG has a use for that article. Meanwhile, A Dios.

 

[Chazzy]

I found a copy of the issue of Petersen's Photographic, April 1973, that contains "Kitchen Tested Soups" and when it arrives I will see if anyone in APUG has a use for that article. Meanwhile, A Dios.

I'm sure that many people would like to see it. Certainly I would.

 

[Kirk Keyes]

I'm looking forward to it. I'd I'm glad you're getting a copy of it again for yourself.

 

[phfitz]

Hi all,

I just bought a $10 digital pocket scale from Harbor Freight Tools, max. 1000g, reads at 0.1g, more than accurate enough.

http://www.harborfreight.com/

Oh, the coins are fine BUT the older pennies weigh more than the new ones.

 

[Toffle]

Let me say for the record that in the world of teaspoon and balance users, I am with the balance group...

But Pat is absolutely right in that this type of accuracy is not required for some work.

Let's try to keep ideology out of this, and avoid the personal insults.

Sandy King

Yes, thank you, Sandy.

 

[Tori8x10]

Phfitz, thanks for the link to Harbor Freight! I'll be going there on Monday to pick up one of those scales.

 

[phfitz]

Hi Tori,

you're welcome. Look for the one that has a clear plastic cover that becomes the scale tray (US Magnum 1000XR)

 

[sanking]

Phfitz, thanks for the link to Harbor Freight! I'll be going there on Monday to pick up one of those scales.

At that price who can live without it?

Some great buys at Harbor Freight. I have several digital thermometers with 6" probes that cost less than $5 and are as accurate as a $100 thermometer that I bought 15 years ago. And for $20 or less they have these infrared thermometers with laser beam that you just aim at a solution and the accuracy is usually +1/-1 degree.

If you have not shopped at Harbour Freight you are not living part of the Chinese/American dream.

Sandy King