On 13/04/2019 09:35, DerbyBorn wrote:
What is the easiest way to seal with a hairline crack in the overskim of a
plasterbaord covered wall.

Do I need to rake it out or can I apply something that will penetrate and
fill it (Creeping Crack Cure?)

The last professional seeing to an issue like this widened the crack and
filled with flexible caulk to take up any movement.