The graphite dust bag is made from finely woven material and has built in draw string to keep the graphite powder in. This has a slightly larger mesh size to allow the graphite to flow through.
The graphite dusting bag should be 25% filled and the draw string tied. It is shaken over and around the pattern and over any surface that easy separation is required from. A fine layer of graphite dust will be deposited over all surfaces. Be careful not to use too much in corners and on fine patterns as detail can be lost.
As well as acting as a parting agent it helps impart a smoother surface to the casting.