If a being that can have banes (such as a Strix, spirit, ghost, etc) has a bane of salt, would a line of salt on a doorway prevent it from entering (like in Supernatural), or would it essentially have to be a wall of salt?
The answer, it appears, is, it depends, just pouring salt doesn't appear to be quiet enough, though if you read abjuration it really isn't much more. I think it's basically that spilled salt wouldn't do it as it lacks intent.
God Machine Chronicle p232, rules update appendix Warding and Binding
Instead of confronting the entity directly as in abjuration, the ritualist marks the boundary she intends to protect with the entity’s bane. She doesn’t have to mark a complete boundary — her concept of the area she’s protecting is what’s important. Marking doors and windows with lamb’s blood to keep out a spirit that can’t touch it will prevent that spirit from simply floating through the wall while in Twilight, and carefully drawing a sigil on the floor will serve to trap the angel whose name it is.