Measuring water with a scale


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Measuring water with a scale

Postby Nathaniel87 » Sep 23rd, '11, 00:20

Hello all~

I just wanted to ask everyone how they measured water volume? I didn't have a graduated cylinder to measure water volume with but I did have a scale. I remembered that the weight of water is typically around 1 gram per ml so it made it very easy to measure fairly precise amounts. It's really useful when trying to compare exact ratios in different sized pots or simply when measuring the volume of a pot. I know many people prefer a more natural and intuitive approach and certainly I would agree when I am drinking normally but once in a while it's fun to let out my tea-scientist side a little too haha.

I know there are a few people here who are more scientifically inclined than me so please correct me if this method is way off but so far it appears to be very precise. Not only is it precise bit also nice because I can simply put the pot on the scale, zero it out, and then pour the exact amount of water I want on a given infusion.
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Re: Measuring water with a scale

Postby Tead Off » Sep 23rd, '11, 02:03

Nathaniel87 wrote:Hello all~

I just wanted to ask everyone how they measured water volume? I didn't have a graduated cylinder to measure water volume with but I did have a scale. I remembered that the weight of water is typically around 1 gram per ml so it made it very easy to measure fairly precise amounts. It's really useful when trying to compare exact ratios in different sized pots or simply when measuring the volume of a pot. I know many people prefer a more natural and intuitive approach and certainly I would agree when I am drinking normally but once in a while it's fun to let out my tea-scientist side a little too haha.

I know there are a few people here who are more scientifically inclined than me so please correct me if this method is way off but so far it appears to be very precise. Not only is it precise bit also nice because I can simply put the pot on the scale, zero it out, and then pour the exact amount of water I want on a given infusion.

I just tested your measurement on a gram scale using 60ml of water which equaled 49.3g in weight. So, your 1:1 figure is not correct. I'm sure it is very inexpensive to buy some measuring cups to give you a more accurate measurement. :D
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Re: Measuring water with a scale

Postby Nathaniel87 » Sep 23rd, '11, 02:44

Interesting~ Out of curiosity, what kind of cups did you use to measure the 60mL of water? I know the density of water varies depending on temperature of the water, but I was under the impression that 1:1 was a safe general rule where ultra-precise measurements were not required.

http://wiki.answers.com/Q/How_many_gram ... ater_weigh

Anyway, I might have to find some cups and test it for myself further.

edit: Even though I know 1:1 ratio varies depending on temperature, I believe that you shouldn't see such a large difference in such a small amount of water. Anyway, I wonder if someone more knowledgeable about science/chemistry that me would be able to enlighten me further just how far off base I am with this.
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Re: Measuring water with a scale

Postby Tead Off » Sep 23rd, '11, 02:50

Nathaniel87 wrote:Interesting~ Out of curiousity, what kind of cups did you use to measure the 60mL of water? I know the density of water varies depending on temperature of the water, but I was under the impression that 1:1 was a safe general rule where ultra-precise measurements were not required.

http://wiki.answers.com/Q/How_many_gram ... ater_weigh

Anyway, I might have to find some cups and test it for myself further.

I used a metal measuring cup, 1 of a set of varying capacities. After deducting the weight of the empty cup, the figure I sent you was the result.
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Re: Measuring water with a scale

Postby Fabien » Sep 23rd, '11, 05:02

Hello TCers

From my scientist point of view : unless your scale is good enough to measure the difference between deionized and mineral water, the ratio weight/volume for water should definitely be 1:1. And it should always be!
No question about that.
So there is probably a mistake in your way of measuring water volume.

IMHO, and talking about teapots' volumes, the best way to measure an "almost" exact volume is the following :
- fill your teapot with water
- empty your teapot in whatever container falls under your hand, container that should have been put on scale before adjusting weight to 0.
- weight in grams = volume of water, with a margin related to your scale's precision.

One can then easily point out the bias that this method generates : everything depends on how you fill the teapot. With or without lid, with or without leaves, with or without showering teapot after filling it up, etc....

From a scientific point of view (which is far away from my tea sensitivity), the best, reliable and comparable way of doing this measure should be measuring without leaves, with lid on and with showering. Because everyone can do this exactly the same way whereas nobody will put the same amount of leaves in a pot.

Thirsty, time to rehydrate :)
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Re: Measuring water with a scale

Postby debunix » Sep 23rd, '11, 10:00

I routinely measure my teapot volumes with the scale, 1 gm water = 1 mL, easily as accurate as my not-so-precise graduated cylinders, and a lot easier.
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Re: Measuring water with a scale

Postby Chip » Sep 23rd, '11, 10:11

debunix wrote:I routinely measure my teapot volumes with the scale, 1 gm water = 1 mL, easily as accurate as my not-so-precise graduated cylinders, and a lot easier.

I remember reading how innaccurate graduated measuring cups were.

I guess I will have to do some weighing ...
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Re: Measuring water with a scale

Postby Tead Off » Sep 23rd, '11, 11:14

Chip wrote:
debunix wrote:I routinely measure my teapot volumes with the scale, 1 gm water = 1 mL, easily as accurate as my not-so-precise graduated cylinders, and a lot easier.

I remember reading how innaccurate graduated measuring cups were.

I guess I will have to do some weighing ...

This seems to be the only reason I can think of to explain the discrepancy as my gram scale is very accurate. I use it to weigh gold, etc., and it matches other scales very closely.
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Re: Measuring water with a scale

Postby betta » Sep 23rd, '11, 13:22

Why so complicated?

You only need to measure weight of whatever glass with water in it, pour that water into the pot you want to measure. And then measure again the weight of the glass. The difference corresponds to volume of the pot as density of water 1g/mL.

No error caused by water left in the pot, not much cumulative error due to number of measurements (only twice with the same device), not much effort, no need for graduated cylinder, but most important it is accurate, no?
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Re: Measuring water with a scale

Postby Bob_McBob » Sep 23rd, '11, 14:59

I think it's important for people to do this with their teaware because so many vendors have inconsistent methods of measuring volume. It's particularly noticeable with gaiwans, because most places don't tell you whether they measured to the brim of the cup, or to the actual usable height where the lid sits. The difference can be significant. I have a "100mL" gaiwan that only really holds about 70mL.

Room temperature water is close enough to 1g/mL that the error isn't worth worrying about. My standard method of measuring teapot volume is to fill it to the brim, gingerly place the lid on so it doesn't shoot water out the spout, then pour the contents into a graduated cylinder. I am not really concerned about getting the volume accurate to a fraction of a mL, but weighing would be more accurate. I'd probably do something like taring the scale with the empty dry pot, following the procedure I outlined above, then weighing the full pot to get the mass of water.

If you use boiling water (I have no idea why you would for this test) the density change produces a 4% error, which is significant enough that a lot of high-end coffee places brew by weight rather than volume.
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Re: Measuring water with a scale

Postby blueye » Sep 23rd, '11, 23:23

using hot water actually expand your teapot, thus you need more say 4%?

well, you don't really have to go to ml. Example I use a porcelain jar/cup to get hot water from kettle, so I use half full, more than half etc to semi quantify the volume in my teapot. Extra hot water use to clean teapot and filter :wink:
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Re: Measuring water with a scale

Postby gingkoseto » Sep 23rd, '11, 23:38

Water is 1g/ml at 4 C. Hot temperature expands water more than expanding the pot in most cases. But that's only if you care about the difference of a few ml.

In fact, I've never bought a yixing or kyusu with the exact volume described by the vendor. Have you? :wink:
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Re: Measuring water with a scale

Postby Bob_McBob » Sep 24th, '11, 01:10

gingkoseto wrote:In fact, I've never bought a yixing or kyusu with the exact volume described by the vendor. Have you? :wink:


In my experience, they usually end up being slightly bigger than the size the vendor states, unless there is a gross description error (e.g. a 100mL pot I bought turned out to be 150mL). I really appreciate when vendors take the time to measure volume and describe it accurately like this ;)
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Re: Measuring water with a scale

Postby Nathaniel87 » Sep 24th, '11, 05:13

I'm glad to hear that it works as I thought. I was afraid for a moment that everything I had been doing until now had been off by such a large margin haha. Anyway, I too have never purchased something that matched exactly the advertised volume. I have two kyusu from Hojo that differ by a fair amount: 1 was advertised as 150 and comes in at closer to 160 while one was advertised as 200ml and comes in closer to 180. Not a huge deal individually but then instead of 50mL difference between the two they are very comparable in size...not really a huge deal for me I suppose. Anyway it'
's still nice to be able to measure volume so quickly and easily.
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Re: Measuring water with a scale

Postby Tead Off » Sep 24th, '11, 10:12

Nathaniel87 wrote:I'm glad to hear that it works as I thought. I was afraid for a moment that everything I had been doing until now had been off by such a large margin haha. Anyway, I too have never purchased something that matched exactly the advertised volume. I have two kyusu from Hojo that differ by a fair amount: 1 was advertised as 150 and comes in at closer to 160 while one was advertised as 200ml and comes in closer to 180. Not a huge deal individually but then instead of 50mL difference between the two they are very comparable in size...not really a huge deal for me I suppose. Anyway it'
's still nice to be able to measure volume so quickly and easily.

Yeah. Sorry to throw you off like that. I had no idea that measuring vessels were off by so much. I had never thought about it before and was never much of a chemistry buff. Glad you're on the right track.

BTW, when Seong il measures his teapots, he never fills them to the rim, always estimates the useable amount. And, even then, it's not exact!
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