Place the CF Sprayer in the middle of a crafting grid and 8 CF Pellets around it to fill it or place 1 pellet in the grid to add a small ammount.
If using a CF Sprayer to spray on a Scaffold it will replace the Scaffold with Construction Foam. You can use a scaffold in combination with Construction Foam to create walls (etc.) without the need to break unnecessary, left-over construction foam. The scaffolds are dropped as entities if replaced by Construction Foam.
As of 1.70, CF will cover and harden around placed cables, allowing one to hide unsightly wiring within CF walls that are only a single block thick.