# Weighing Issues

Discussion in 'Beginners Soap Making Forum' started by carrie71, Feb 13, 2020.

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1. Feb 17, 2020

### JakeBlanton

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Doesn't matter... Do you bake? Then you *should* be using dry cups in your measurements for flour and sugar (unless you using *weight* like you really should). If you are using dry cups, they relate to dry pints and dry ounces. Typically, the *dry* cup measuring devices will NOT have a pouring spout on them and you are expected to run a knife or other straight edge across the top to ensure that the level of the measured substance is equal to the top of the measuring device. That is completely different than the fluid measuring devices where you attempt to line up the level of the substance with the graduations in the measuring device.

Now, if you really want to get into arbitrary measurements, look at how some recipes call for a *rounded* teaspoon or a *heaping* teaspoon. Measuring by weight is the way to go (no pun intended). Regardless of whether you use the metric, US Customary, or British Imperial system of measurement.

2. Feb 17, 2020

### DeeAnna

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I have spent many years cooking and I assure you I know my way around a kitchen and have acceptable cooking skills. I currently have measuring cups for dry measuring by Tupperware and glass measuring pitchers for liquids by Pyrex.

The 1 cup measure for dry measuring contains exactly 8 ounces of water by weight. The measuring pitcher contains exactly 8 ounces of water by weight if I measure 1 cup by volume.

In other words, in my kitchen 1 cup by volume is the same no matter what I use to measure that cup.

I rest my case.

3. Feb 17, 2020

### JakeBlanton

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Then your measuring is not accurate enough. I'm an engineer, there IS a difference. It's possible that for what you are doing though, the difference is not enough to affect what you are doing, but there IS a difference none the less.

4. Feb 17, 2020

### MGM

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No sir, basing a system of measurement on orders of magnitude is not arbitrary. Pecks, bushels, cubits, pints, ounces, miles, pounds, farts, and wheezes are units that have no relationship to each other and really, truly, are the very definition of arbitrary.

5. Feb 17, 2020

### JakeBlanton

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The metric system *tried* to have the units of measurement defined as intrinsic units (i.e. the meter being originally defined as 1/10,000,000 of the distance between the equator and the North Pole along a Great Circle route and a kilogram being defined as the weight of 1,000 cu-cm of water), but as we advanced, we found out that our reference units were not quite in agreement with the physical constants. We eventually redefined them in relation to things like the speed of light and universal constants like Plank's Constant). As such, they are no longer based some physical value that makes sense to everyone, but rather just some sort of approximation of this, thus they end up being just arbitrary constants. Orders of magnitude are nothing special -- various fields in the US already use decimals in their measurements. For example, mechanical engineers and machinists routinely use measurements in 1/1000ths of an inch for parts that are being manufactured. I have worked in US Customary, metric, and Imperial units and have no problem with any of them. I have enough experience in them though, that I can say without bias that they are all just arbitrary units and there is nothing special about ANY of them.

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6. Feb 17, 2020

### DeeAnna

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Trot into your own kitchen and see for yourself before you start pointing fingers at me about this.

If my dry cup is indeed a "dry 1/2 pint" measure, then 1 dry cup should contain 9.3 ounces by weight of water. The difference between a "wet 1/2 pint" of 8 wt oz and a "dry 1/2 pint" of 9.3 wt oz is a 16% error.

Converting back into kitchen measurements, that is well over 2 tablespoons difference. Even if I deliberately over-poured into the dry cup measure, the meniscus formed can't remotely contain that much liquid.

"... I'm an engineer, there IS a difference....."

Oh, dearie me. Having you reveal you've reached the pinnacle of a degree in engineering is going a long way toward proving your point is correct.

So my challenge -- Get into that kitchen and check your cup measures. Is the dry measure the same volume or a different volume than the wet measure? Can you actually put an entire 9.3 ounces of water by weight into that dry cup measure? With a flat meniscus, of course.

I thought engineers were supposed to be practical people, so I'd sure like to know what you find out.

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7. Feb 17, 2020

### StormyK

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I am not an engineer, but I've spent the last 8 years working directly with them at an engineering consulting firm (many of whom are Ph.Ds to boot) and I can confirm that loads are most definitely NOT practical people.

Dont get me wrong, some are absolutely brilliant (both intellectually and just as 'people'), but the ones who toss around their titles / designations usually dont fall into that category...

8. Feb 17, 2020

### JakeBlanton

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Not a perfectly accurate measurement because the temperature of my tap water is not 4C, but I got 500g for 2 cups (16 fl-oz), so 17.637 ounces weight. I don't have a dry measure cup. Because of the diameter of the liquid cup, the meniscus could make a difference, but I tried to put it on the line as best as possible. For an accurate measurement, you would use a graduated cylinder which if a lot taller and thus the discrepancy of the meniscus would not affect it as much. A dry pint is roughly ā 551 ml and a liquid pint is roughly ā 473 ml. So, my Pyrex measuring cup is apparently somewhere between the two. It's not unexpected that it would not be accurate since it's just used for cooks, not for chemists.

And it's DEGREES, just just *A* degree... I'm retired now, so it doesn't really matter, but back then, knowing which units to use and how to convert between them was kind of important.

There's being practical and then there's being accurate... We prefer to be accurate rather than practical. Especially when our designs have lives dependent upon them. You mess up your soap calculations, the worst that can happen is you make a mess on your counter top. If we made a mistake on some of the DoD, aerospace, and NASA projects that I worked on, people could die. Next time you get on a plane, think about that...

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9. Feb 17, 2020

### StormyK

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Oh, I do think about that. It's one of the greatest negatives about working with people who carry a certain level of status alongside their job - you quickly learn that en masse they are just people... just like the rest of us.

Maybe you were one of the good ones. All I'm saying is that having a P.Eng, M.Eng, etc. doesnt inherently endow a trait. Plenty of engineers make mistakes, plenty struggle with the pin-point accuracy, and plenty are straight-up just not good at their jobs.

Also, I tend to laugh at people who throw around statements like "I'm an engineer so...", "when I worked for NASA...", and so forth. It's straight up jostling for status and when you have the science, stats, proof to back up your arguement, that sort of strutting really isn't necessary. Especially not on a soap-making forum. It just seems petty - particularly for an individual as accomplished as yourself.

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10. Feb 17, 2020

### JakeBlanton

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Just pointing out that I have a science / engineering background and am not some Gen-Slacker kid who thinks that he knows what he's talking about just because he has some stupid app on his phone.

11. Feb 17, 2020

### cmzaha

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Guess what you are not the only one in this forum with science/chemistry/engineering degrees. No not me, but some do not feel they have to advertise and brag about their degrees, or as StormyK stated, Strut their degrees. There is really nothing more irritating. I was always glad my genius, Mensa, rocket engineer friend was very down to earth, never bragged, never acted as if he was better. He rode his Harley just like the rest of us.

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12. Feb 17, 2020

### DeeAnna

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"...I don't have a dry measure cup...."

So you can't and won't collect the one critical piece of information that you (not me -- YOU) need to support your assertion that dry measuring cups are indeed different than liquid measuring pitchers. It's pretty clear you're arguing this point for argument's sake.

"...Just pointing out that I have a science / engineering background..."

You are far more interested in touting your resume than contributing meaningfully.

"...am not some Gen-Slacker kid who thinks that he knows what he's talking about just because he has some stupid app on his phone...."

You have only been participating in this forum for a mere 7 days, but you think you are qualified to make snarky judgements about people here. That is rude and uncalled for.

Enough already. Let's get back to the OPs topic -- volume ounces versus weight ounces.

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13. Feb 17, 2020

### Todd Ziegler

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You have received a lot of answers but I didn't see anyone ask you about what brand of scale you are using and what it is capable of doing. For example; does your scale go to 0.1 or 0.01,can your scale be calibrated etc. There are a lot of scales for sale and most are junk as far as soap making goes. If you have time please tell me what you have and its capabilities. I recommend that you get the best calibration weight you can afford, M1 or F1 or F2. Even if your scale can't be calibrated, a good calibration weight can tell you how far off your scales are. Even a 50 gram or 100 gram F1 scale can be a great help but a 200 gram would be better, unless your scale can be calibrated and then you will need what ever size your scale manual calls for.

14. Feb 17, 2020

### JakeBlanton

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Awh, did I trigger some of the snowflakes here? Bless their hearts...

What you are getting when you measure the weight of a "cup" of water really doesn't mean anything because we don't know if it is truly accurate. I stumbled across another measuring liquid measuring cup in the kitchen and decided to give it a try. I measured out 2 cups from it an poured both of them into the 2-cup Pyrex unit that I had previously used. The water ended up around 1/8" below the "2-cup" line. Obviously at least one of them is in error -- maybe both. All you have to do is look at the measuring standards definitions and you'll see that there is a difference in the volume of a dry-cup / dry-pint / dry-ounce and a fluid-cup / fluid-pint / fluid-ounce. If you are getting the same weight for the dry and fluid measures for your "cups", then something is in error. It just cannot happen and they be truly a dry-cup and fluid-cup. Either they are slightly off (like my two fluid cups) or they are not what they claim to be. No matter how much you insist that in your case they are the same, the fact of the matter is that according to the legal definition of these units they ARE different. In the end though, what this really tells us with respect to the question at hand is that we cannot trust the volume measuring containers sold for kitchen use for soap recipes.

I reload my own ammunition for the various calibers that I shoot. Part of the reloading process is measuring out the powder. We tend to use volume based powder measures, but when setting them up, we weigh the powder that is dropped by the unit to the nearest 1/10th of a grain (7000 grains per pound) and periodically recheck it during the reloading session to ensure that it doesn't change. The guys who do the long range benchrest shooting are extremely concerned with getting exactly the same powder charge for each shot since inconsistent charges will result in variations of the muzzle velocity of the round, thus resulting in it hitting the target slightly higher or lower. As such, they weigh each and every charge.

So, whether you are making soap, cooking, or reloading ammunition, you can possibly get away with developing a "recipe" based on volume and it might even work well enough for a particular set of volume measuring devices, but the "recipe" might not work the same for someone else with a different set of volume measuring devices. As such, measuring by weight is advised.

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