'blending in' patches of plaster (wall & ceiling)

red_imps_2003

Hopefully this is the last time I will have to pester for help for a while. Following the removal of a chimney stack and breast recently the builder 'made good' the wall and ceiling by filling the gap with plaster rather than doing the whole wall, which is fair enough as we never really discussed the option of re-plastering the whole wall to keep it neat. See the result here. I will, of course, be removing the wallpaper before redecorating. We will almost certainly put new wallpaper on that wall, which should mask over the 'join' between the new plasterwork and the old, but I am more anxious about the ceiling. The plasterwork itself is sound (nice, smooth finish) but where it is blended in with the surrounding ceiling is a little rough. I would like to try and make the join as seamless as possible once I have painted the ceiling. My question is, should I sand this down before I paint or is that likely to make the patch more noticeable? There is another patch in the middle of the ceiling where he has kindly moved the light fitting, which was no longer central once the breast was removed. See here.

red_imps_2003

Just bumping this, as I posted at an anti-social time the other day. Does anybody have any advice for ensuring the 'blend' between the new plaster and the existing one is as seamless as possible once painted please?

Silver-Surfer_2

Give the edges of the ceiling plaster a sanding before you paint. Sand it so you cannot feel an edge, mist coat the new plaste and after a couple of coats of paint you shouldn't see the repair.