Filling holes in crumbling plaster

Showing you an easy and successful way to fill holes when the plaster is really crumbly, for instance when you have old lime plaster or if the backing plaster has degraded.
Tools used:
Scraper
Vacuum cleaner (optional)
SBR primer
Small brush to apply primer
Powdered wall filler
Sander:
-Sanding block
-Hand sander
-Mirka Deros