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Viscometer
Can anyone recommend a viscometer that’s not going to cost an arm and a leg but still effectively get the job done?
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12 Replies
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You can build one yourself:
1 Buy plastic graduated cylinders (IMO 50-100 ml work fine)
2 Drill a hole in the bottom. The hole diameter depends on the viscosity range you’re willing to test.
Even wikipedia ‘Flow cups’ article gives great info
https://en.wikipedia.org/wiki/Flow_cups3 Get a stopwatch (even a smartphone app can work fine)
4 Fill it up with the bottom hole plugged.
Unplug and measure the time it takes to partially empty by gravity
i.e. from 50 to 5 ml. You may want to paint the cylinder marks to make them easily readable.
don’t allow to fully empty as it ain’t accurate there.You may wish to buy a bottle of your favorite commercial product with the proper viscosity you’re looking for, or get some liquid with a known viscosity as a “calibration standard”.
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Gunther’s idea works well.
Or you can measure the time for a (eg) marble to sink a given distance.
Or measure the time taken for an air bubble injected from a pipette to rise a given distance. -
Thank you! I will try that. And good point about it not emptying all the way.
Can you tell me what I should expect to pay for a decent one on the market after I have a chance to save toward its cost?
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@RenKB price depends if you want a “mechanical” or a digital one
You can start here:
https://www.labx.com/v2/adsearch/search.cfm?sw=viscometer&sort=p&sortDir=aHint: choose one that’s easy to clean up. Most aren’t, especially those made of curved glass.
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@Gunther, i just want to get a little more clarity on your article above. Since i make shampoos all who are around 1200 - 3000 mpas then i should use a 8mm hole at the bottom of the cup?
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Yes, but you’d need something to compare flow-times to
either
A. Reference fluid with the desired viscosity. Either lab-grade reference standards like these
https://www.sigmaaldrich.com/analytical-chromatography/analytical-products.html?TablePage=113813044
or a bottle of your favorite commercial shampoo (not very accurate, but allows a better comparison to commercial products).B. A professional viscometer with viscosity tables
like these
https://www.thomassci.com/Equipment/Viscometers/_/FORD-VISCOSITY-CUPSYou can always start smaller, say 6mm hole
and then drill it bigger, if flow is too slow. -
If you want cups pre-made try looking at places that sell automotive refinishing products - they’re used for checking paint viscosity before spraying, or google “Ford cups”
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Just check the paint cups specs
Paint, especially those meant to be sprayed are way thinner than shampoo
https://www.hallmach.co.nz/public/db_files/1504567179.pdf -
@Gunther, reached out to a lab supplier and the following is their oem supplier response “Afternoon Sven
Herewith feedback from our supplier.
Hope this helps
Mpas is the same as centipoise.
Cups measure Centistokes. To convert from centistokes to centipoise, the density of the liquid is required.
Assuming the shampoo is a similar density to water (1) then centipoise and centistokes are equal. 1200 to 3000 is outside the range of all cups.
I suspect the shampoo is thicker than water so I would need to know the density to be sure, but don’t believe a No 4 cup would be suitable for this application. Maybe no cup will be in this range.
Which type of cup is it?
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You need to read the specs for that cups manufacturer.
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Interesting discussion.
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