What are Crock Blocks for James Heal Crockmeter and Crockmaster?

The Crock Blocks for the CrockMeter and CrockMaster are interchangeable fingers created to test textile floor coverings and other pile fabrics according the the standards ISO 105 x12 and AATCC 165.

The rubbing finger has a rectangular rubbing surface with the lead edge rounded measuring 19 mm × 25.4 mm. 

It is used in place of the 16 mm diameter cylindrical rubbing finger due to difficulties which might be experienced in making assessments of the degree of staining on the rubbing cloth when pile fabrics are tested using the 16 mm diameter rubbing finger due to heavier staining occurring on the circumference of the stained area, i.e. haloing. The CrockBlock will eliminate the haloing with many types of pile fabrics. 

The Crockmeter model 255 Crock Block Finger (794-541) has a cylindrical spigot with a flat face for a clamp screw.

The CrockMaster model 670 and 680 Crock Block Finger (794-998) has a triangular shaped anti-rotation spigot.