My OED gives one meaning of "fash" as:
"A rough edge or ridge left on nails, cast bullets, etc"
It gives a second meaning as:
"A fringe; anything resembling a fringe".
It defines "burr" as:
A rough ridge or edge left on metal or other substance after cutting, punching, etc.; e.g. the roughness produced on a copper-plate by the graver; the rough neck left on a bullet in casting; the ridge produced on paper, etc., by puncture.
Edited By Peter Greene 🇨🇦 on 30/03/2023 21:28:31