After the glass has been gathered onto the pipe, it is thick and viscous like molasses or honey.

Blocking achieves several important purposes:

1. it shapes the glass gather to the proper initial shape
2. it cools the outer surface of the gather to allow the initial bubble to form
3. it centers the gather on the pipe

A few notes about blocks:

Blocks are made of fresh green wood and must be kept soaking in water whenever they are not in use. When a block is used properly, the heat from the glass evaporates the water in the block to form a cushion of steam that the bubble rides on and prevents the hot glass from burning through the block.