What is a grinding dummy block?

What is a grinding dummy block?

The "dummy Block" helps to prevent "grinding dry with fluid" by. Guiding fluid to the height of the workpiece before wheel contact is made.

This style of dummy block is not to be confused with a dummy block used for plunge or creep feed grinder we do not actually cut into our dummy blocks when we're using them to control the flow of coolant too our work piece
Example of grinding without using a dummy block

https://youtu.be/7R2AfmXpNfs

Thanks for that very useful tip.