At one end of the spectrum of the moisture world is the classic Speedy Moisture Tester where you use the reaction of water with calcium carbide to cause a mini explosion resulting in a moisture measurement reading. This method is used frequently for soils, concrete, and other like materials.

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Topics: Moisture Sorption Isotherm, Moisture Analysis, Water Activity, Karl Fischer, Loss-On-Drying

Many accessing our web site ask questions such as:

• “How does water content affect water activity?”

• "How is water activity different from water content?”

• ”Can I convert from moisture to water activity?”

I previously commented on water activity and now hope to clarify the differences between water activity and moisture content. Given that both of these measurements deal with water connected to a material, we must first understand of water content in a product.

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Topics: Moisture Sorption Isotherm, Moisture Analysis, Water Activity, moisture content, moisture measurement, water activity measurement, water content measurement

Loss-On-Drying moisture analysis seemed like a simple process until, in a state of naïve bliss, I promised to look at evaporation, vapor pressure and bound water. While I was otherwise occupied with hese realities, I offered to enter the world of witchcraft and folklore; water activity.

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Topics: Bound Moisture, Moisture Sorption Isotherm, Moisture Analysis, Water Activity, Loss-On-Drying

Do an internet search for the term “viscosity”, and you’ll find a variety of definitions for the word. For example:

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Topics: Viscometers, Viscosity

When people hear of viscosity for the first time, invariably they ask these three questions:

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Topics: Newtonian Fluid, Measure Viscosity, Viscometers, Viscosity, Viscosity in Food

When our customers tell me about the different places where CENCO and CSC Digital Moisture balances are used it always interests me.

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Topics: Moisture Analysis, Moisture Testing, Loss-On-Drying, Moisture, moisture content, water content measurement

Water Activity

Water activity is the water in a material available to support the growth of microorganisms.  Consequently, the measurement of water activity is important in areas such as food processing, pharmaceutical production, products affected by mold, and a host of products that change characteristics when exposed to moisture.

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Topics: Water Activity, stop mold, chilled mirror, aw

The most popular was to measure include:

1. Drying the material and measure the weight loss 
2. Using a calibration and electronic instrument 
3. Using a titration method such as Karl Fischer

When using these processes, we take for granted that the results will be the product's actual moisture.

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Topics: Evaporation, Moisture Oven Test, Infrared Moisture, Moisture Analysis, Moisture Testing, Karl Fischer Titration, Loss-On-Drying, evaporator oven

I was musing, the other day on the designs of two ring tensiometers. One of them is called an interfacial tensiometer and the other simply a tensiometer. The plain tensiometer works only with an upward pull and the interfacial works with both an upward pull as well as a downward push. Before I get to my question a couple of definition might be useful.

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Topics: Surface Tension Measurement, Surface Tension, interfacial tension, interfacial surface tension, surface Tension Testing, du Nouy Ring Method, du Nouy tensiometer, Liquid Properties

Shear Stress - Shear Rate

Viscosity! If you ever think about it, what do you see?

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Topics: Newtonian Fluid, Viscometers, Dynamic Viscosity, viscometer, rotational viscometer, Viscosity Stress, Viscosity Shear Rate, Non Newtonian