[Nhcoll-l] [EXTERN] Digital Density Meter

Mon Jun 8 16:45:23 EDT 2026

Besides Anton Paar, Mettler Toledo also offers (handheld) digital density meters. Both offer great instruments, though quite expensive.

Just to be more precise about its operation: The working principle of an oscillation-type density meter is based on the law of harmonic oscillation, in which a U-shaped thin-walled borosilicate tube is completely filled with the fluid sample to be analyzed, and subjected to an electromagnetic force. The measurement of the frequency and duration of vibration of the tube filled with the sample, allows the determination of the density value of the sample. The first oscillation-type density meters were subject to errors induced by the viscosity of the samples. Modern density meters have measurement cells which apply the viscosity correction of the sample, thereby avoiding the systematic errors of the early instruments.

Reference: Furtado et al. 2009. Measurement of Density Using Oscillation-type Density Meters: Calibration, Traceability and Uncertainties. 14ème Congrès International de Métrologie, Paris, France. 

Andries J. van Dam

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Van: Nhcoll-l <nhcoll-l-bounces at mailman.yale.edu> namens John E Simmons <simmons.johne at gmail.com>
Datum: maandag 8 juni 2026 om 17:59
Aan: Dirk Neumann <d.neumann at leibniz-lib.de>
CC: <nhcoll-l at mailman.yale.edu>
Onderwerp: Re: [Nhcoll-l] [EXTERN] Digital Density Meter

I have noticed that there seems to be a bit of confusion about how the concentration of alcohol can be measured when managing a fluid-preserved collection (e.g., a device with no electronic or mechanical parts does not work the same way as a digital density meter). Which one you decide to use will depend on several factors, including cost, the amount of fluid required, ease of use, and what fluids you are measuring.

For use in managing fluid-preserved collections, there are three basic types of devices that are commonly used—each uses a different technology and different amount of fluid to determine alcohol concentration (there are other ways to measure density that are not practical for use in collection management).

A refractometer measures the refraction angle of the light going through a few drops of liquid and correlates it to a refractive index. Refractometers do not work with alcohol that has glycerin added to it.

A hydrometer measures specific gravity, the old Archimedes principle of buoyancy in which a solid body displaces its own weight within the liquid in which it floats, and requires enough fluid and a large enough container to float freely.

A digital density meter requires 2-3 ml of liquid which is electronically stimulated so that the frequency of oscillations of the molecules can be measured.

For a large, heavily used collection, a digital density meter is most efficient. If budget is an issue and the alcohol does not have glycerin in it, a refractometer is the least expensive option. Hydrometers are limited by the amount of fluid being tested—small hydrometers are available but smaller instrument have smaller the scales that are more difficult to read and are less precise.

John E. Simmons

US Fulbright Senior Scholar
Writer and Museum Consultant, Museologica
and
Research Associate, Earth and Mineral Sciences Museum & Art Gallery, Penn State University

and

Investigador Asociado, Departamento de Ornitología, Museo de Historia Natural, Universidad Nacional Mayor de San Marcos, Lima

On Mon, Jun 8, 2026 at 12:41 AM Dirk Neumann <d.neumann at leibniz-lib.de> wrote:

Hi Katherine,

many are using the handheld alcohol density meters of Anton Paar: https://www.anton-paar.com/corp-en/products/details/snap/

Anton Paar has a worldwide distribution network and sells in Africa, Australasia, Europe North- and South America.

Less expensive and perhaps more convenient are small traditional manual density meters that fit into jars. few years back, Gassner Glastechnik manufactured small calibrated (60/70/80 % EtOH) 5cm alcohol metres which allow direct measuring inside jars.

The advantage is that they are small and have no electronic or mechanical parts that need maintenance or could fail, they also do not need calibration, and are easy to apply. Even though manual alcohol metres are less accurate and cannot show the alcohol concentration with two decimal places, they are accurate for fluid preserved collections.

Also, alcohol metres have no tubing that need to be cleaned/rinsed after measuring (oils, fats, denaturing agents).

Hope this helps

Dirk

Am 05.06.2026 um 22:42 schrieb Katherine Dunnell:

Hello Everyone!

Can anyone recommend a digital density meter they like using for wet collection top ups? 

Would love to hear what others are using within these collections.

best

Katherine

Katherine Dunnell (she/her)
Manager, Collections Care - Natural History

100 Queen's Park
Toronto, ON M5S 2C6
416 586 5816
 Royal Ontario Museum is an agency of the Government of Ontario.ROM acknowledges that this museum sits on what has been the ancestral lands of the Wendat, the Haudenosaunee Confederacy,and the Anishinabek Nation, including the Mississaugas of the Credit First Nation, since time immemorial to today.

Le Musée royal de l'Ontario est un organisme du gouvernement de l'Ontario.Le ROM reconnaît que le Musée est situé sur les terres ancestrales des Wendats, de la Confédération des Haudenosaunee et des Anishinabes, y compris la Première Nation des Mississaugas de Credit, et qu’ils occupent ces terres depuis la nuit des temps.

On now at ROM, BEES: A Story of Survival. Book tickets at rom.on.ca.

À l'affiche : LES ABEILLES : Une histoire de survie. Billets en vente sur rom.on.ca/fr.

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Stiftung Leibniz-Institut zur Analyse des Biodiversitätswandels
Postanschrift: Adenauerallee 127, 53113 Bonn, Germany

Stiftung des öffentlichen Rechts;
Generaldirektion: Prof. Dr. Bernhard Misof (Generaldirektor), Adrian Grüter (Kaufm. Geschäftsführer)
Sitz der Stiftung: Adenauerallee 160 in Bonn
Vorsitzender des Stiftungsrates: Dr. Michael H. Wappelhorst

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NHCOLL-L is brought to you by the Society for the Preservation of
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mission is to improve the preservation, conservation and management of
natural history collections to ensure their continuing value to
society. See http://www.spnhc.org for membership information.
Advertising on NH-COLL-L is inappropriate.

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