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Why Not A Bostwick Consistometer Calibration Standard?

Posted by

Art Gatenby on Nov 24, 2021 4:00:00 PM

Customers Want Bostwick Consistometer Calibrations.

When told that CSC Scientific does not calibrate Bostwick Consistometers, people ask .Then how can I calibrate my consistometer and where can I get a calibration standard?”.

Sampling Method Using Your Product

We recommend sampling the selected Bostwick Consistometerproduct to be measured  using the Bostwick Consistometer. The sample should represent your product in its ideal state. The temperature should be carefully recorded and a test run. The time it takes to get about half way down the trough should then be recorded.

This process will set a standard or an expected result for a perfect product. From this baseline, acceptable limits should be set by time. For example, a reading of 16 in 85 seconds might be the standard for a perfect product at 30° C. Acceptable variations can range from a reading of 16 in 81 seconds to a reading of 16 in 89 seconds. Again, the product temperature should be 30° C.

Acceptance Standards Set For Each Product Independently

A similar ISO Documentationprocedure should be followed for each of your products tested with the Bostwick Consistometer. The standards thus should be recorded in a QC results chart and stored as reference for ISO or similar quality control inspections.

This table shows typical standards and acceptable limits for three hypothetical products:


Marbleized A

Syrup C

Mission 5

Product Temperature


42° C


Distance Standard




Time Standard

85 Seconds

58 Seconds

42 Seconds

Allowable + Time

81 Seconds

62 Seconds

46 Seconds

Allowable - Time

89 Seconds

55 Seconds

40 Seconds

Calibration Standards

We have had frequentreference standards requests to develop a reference standard for ISO and other quality control inspections. In an attempt to meet these requests, CSC Scientific conducted extensive research to find a suitable material - a material with a consistent viscosity that would repeat results from test to test. The problem we had with seemingly promising materials was a high sensitivity to small temperature changes. After exhaustive experimentation, we concluded that the prevalent effect of temperature on Bostwick Consistometer results abrogated the practicality of a universal standard.

The critical issue in consistent and repeatable CSC Bostwick Consistometer operation is in the set-up. Leveling the trough is the principal requirement for getting repeatable results on a sample at a fixed temperature.

Establishing and recording Bostwick results on the perfect or quality control standard Ketchupproduct is the only practical way to develop a calibration. This should be done with the user’s product at the testing site.

Sorry to have to carry this message. You have to do your own calibration for each of your products.

I hope this was helpful to you.  Please share this with everyone who needs to know.

As always a perplexed,


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P.P.S.  If you need A Bostwick now, click on the Order On Line Button.

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Topics: Bostwick Consistometer, Consistency, Calibration, Liquid Properties

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