The consistency of a sample is measured by its resistance to flow under specific conditions, for a specified time. The Bostwick Consistometer is designed to make such measurements. The following steps are how to test for consistency.
Step 1- The Bostwick Consistometer is designed to sit at a specified angle. The instrument must be adjusted to ensure that it is at this angle. Locate the two twist screws in the rear of the instrument as illustrated in I. Both of these may be adjusted to raise or lower the sides of the instrument. Adjust the two screws until the leveling bubble on the front of the instrument is centered as shown in II A and II B.
Step 2- Close the product gate by pulling it down (A) and while holding it in this depressed position, pulling the lever arm up as far as it will go (B). The product gate is now in its cocked position (C).
Step 3- Pour the desired sample into the sample reservoir as shown in A and B. Fill the reservoir up to the top of the product gate (C).
Step 4- Release the product by pressing down on the lever arm (A). Allow the product to run along the slope for 30 sec (B).
Step 5- Record at how far the product ran down the slope in the 30 sec. The slope has graduation marks indicating the distance in centimeters. This value as the consistency of the product
It is very important that the Bostwick Consistometer be dry before using it. Water will decrease the friction coefficient of the instrument and result in false readings.