Filling cracks

[JohnBoyII]

I had some internal plastering done just over a year ago and some cracks have appeared in the last couple of months, some hairline and a few bigger ones. Any suggestions why they've appeared?. The surface was cement rendered (and bone dry) before plastering but it was done in the middle of winter and they used fan heaters to dry the walls at times. I thought it might be because it wasn't allowed to dry "properly" but a mate said that maybe the Gypsum wasn't mixed properly?

Whats the best stuff to fill both types of cracks?

 

[Nige F]

Tetrion powdered filler

 

[JohnBoyII]

Is that better than the ready mixed polyfilla stuff?

 

[masona]

The best one I used are the Easi-fill which are made by Gypsum