I bought a scale to measure very small quantities in 0.01 increments.
The scale has a calibration weight of 50 grams and it measures so +/- an error as expected.
My intention for the scale is to measure powder/herbs.
To try it I have a measuring spoon that says 1.25 ml and I used cinnamon as a sample and scooped it, use a knife to flat out the top and when I weighed it the scale reported 0.5 grams while I was expecting 1.25 grams.
I tried with regular sugar (not powedered) and the weight reported is the same as the measuring spoon e.g. for 2.5 ml the scale reports 2.5 grams etc.
So now I am confused. Is there a difference when using powder and measuring spoons? What's the issue here?
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3See this table. Ground cinnamon has a density of 0.5 grams per cubic centimetre (per millilitre). 1 cubic centimetre = 1 millilitre. So, your scales and measuring spoon are correct.– Billy KerrCommented Jan 31, 2023 at 12:48
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@BillyKerr: Thanks! So what is the difference with oil or sugar? I can't find those in the page you shared.– JimCommented Jan 31, 2023 at 12:54
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8All ingredients have different densities. It just so happens that some will be equivalent in millimetres as they are in grams. You can't assume all ingredients will weigh the same based on volume.– Billy KerrCommented Jan 31, 2023 at 12:59
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@BillyKerr: Very helpful especially the page you shared thank you– JimCommented Jan 31, 2023 at 13:01
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1The site's confusing. That link takes me to "SUGAR 'N SPICE [brand], PAPRIKA". I think if you uncheck "Branded Foods" when you search you get better results.– Peter MooreCommented Jan 31, 2023 at 14:42
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2 Answers
I think you are mixing up volume and weight.
Your spoon is measuring a volume, giving you ml of the substance that you scooped. To convert this volume into a mass, you need to multiply it by the substance density in mg/ml.
Additionally, powders and coarse materials like ground herbs will not have a constant density, because of the empty spaces between their parts, which change with how you pour/scoop them.
Try shaking a container filled to the edge with herbs, and see how the level seems to diminish as the herb fragments pack better.
If you want to carefully measure weight for loose substances like powders or ground material, use a scale, not a spoon.
As a reference for how big this effect can be, I routinely store my muesli in a glass jar. By directly putting the muesli in the jar, about 10% remains in the bag. After gently shacking the jar, the whole content can fit in.
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So what is the difference when measuring with sugar or oil and the measurement matches?– JimCommented Jan 31, 2023 at 12:52
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1@Jim: liquids are going to give you consistent volume measurements, but it may not be 1g/mL (although many are close). Granulated items have the potential to pack differently based on a lot of factors so trap air and won’t be a consistent grams per mL but if item is dense the amount of air might bring it back near 1g/mL– JoeCommented Jan 31, 2023 at 14:51
Volume and weight are two different measurements, a spoon of powder won't weigh as much as a spoon of oil as they have different densities.
However, a handy thing to keep in mind is that with the metric system 1 gram of water = 1ml in standard conditions. So, a flat spoon of water at 1.25ml will weigh 1.25 grams. As long as your scale measures that accurately then it is correct.
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I did the test of the water. It was roughly the same. It was very difficult to add water exactly at the brim of the spoon– JimCommented Jan 31, 2023 at 18:43
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3At this level of precision the scale should be far better than the spoon. That's why I commented under the Q that it might be a good idea to plot a graph of g on the y axis against ml or spoonfuls on x– Chris HCommented Feb 1, 2023 at 11:11