CSC Blog

Why Not A Bostwick Consistometer Calibration Standard?

Written by Art Gatenby | May 11, 2011 4:35:00 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?”.

We recommend sampling the selected product 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.

A similar procedure 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

30°C

42° C

50°C

Distance Standard

16

17.5

15

Time Standard

85 Seconds

58 Seconds

42 Seconds

Allowable + Time

81 Seconds

62 Seconds

46 Seconds

Allowable - Time

89 Seconds

55 Seconds

40 Seconds

We have had frequent 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 product 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.

As always a perplexed,

Art

P.S. Did you know that you can subscribe to these exposés, rants, raves and ramblings? All you have to do is click on the RSS Feed symbol at the upper left and you will get a notice when a new one is published. Or, if you prefer, you can also subscribe for e-mail notice by jotting your address in the box just to the right of the title.