Harry describes the dust as being "something extra-real, that it was heavy and inert and locked spiritual matter into place when it touched it." The dust is able to affect the ghost even in the mortal plane. Upon contact, it sparks into "blazing motes of scarlet light", apparently causing them pain and immobilizing their ectoplasmic flesh.
In the Nevernever, the weight of the ghost dust increases significantly, weighing "thirty or forty pounds" for a small pouch. Harry Dresden believes that, if released, it would tear a hole in the Nevernever.
In the series Edit
- Main article: Grave Peril
In Grave Peril, it's used by Harry Dresden to combat ghosts. Harry dumps the remaining Ghost Dust in his pouch onto Leanansidhe. Harry's Ghost Dust contains iron, a bane to Faeries—Lea screamed as her skin tore and burned.
Mortimer has a variation mixed into the paint in his room to prevent ghosts from entering.