Cracks in paint vs cracks in plasterboard

[Juliapinkiepie]

Hi fellow DIYers,

Firstly, I'm baaaaaaaaaack! after a 2 year hiatis I'm back to gain some skills and pass on skills that I know.

Today my question is on wall surfaces and prep that needs to be done before painting or wall papering. Please note that due to having no formal education in painting or carpenty I don't know the words for some things so bare with me.

A) How can I tell if there's a hairline crack in the paintwork or if its in the plasterboard and B) How I prep for these before painting

[AHoy]

@Juliapinkiepie

It doesn't matter how deep the crack is, the approach is the same. It's all about getting a nice smooth finish to paint on. Give it a light sand and see if you can make the surface smooth. If you've got a crack, use a filler, then sand again. Fillers are really easy to use and you'll get a nice smooth finish after sanding and you'll be ready to paint. 

There was a similar recent post here - https://www.workshop.com.au/t5/Whole-of-House/Patching-holes-in-the-wall/td-p/19360