Finishing ripped plasterboard

If it's only a small area, just use cellulose filler, then sand + paint.

Okay, will do. I'm remarkably crap, even with Polyfilla. I've just tarted up my airing cupboard, and my filling of non-tiny areas is okay, but even after a sanding, there is a visible line at the edge of the filler. Did I miss something? Just more practice perhaps?

This surprises me - it is easy to get a very good finish with cellulose filler.

Perhaps you're not sanding enough?

Yes to the PVA, not sure about plaster... What I'd do is PVA (not weaker than 50/50, perhaps more like 70/30), then Polyfiller - add a drop of PVA to that if desired - but I've had no problems using it either way on PB damaged areas.

HTH

Tim

Perhaps. I sanded to the point where I was sanding through the paper covering the surrounding good board. Either the board's not flat and / or I'm cack-handed with a sander.

Before you fill, go along the edges with a Stanley knife at about 45 deg to bevel the edges, remove any torn paper/loose bits. Apply dilute PVA then fill just proud with Polyfilla, covering a greater area than you need. When dry, gently sand and brush out the dust. Wet the area again and skim any lowspots, leave to dry again and then sand using a fine grade of paper, sand to a smooth surface. Avoid at all costs sanding the paper face of the plasterboard or you will be chasing your tail ;-)

HTH

Steve.

Try car body filler, easy to sand and feather an edge. If you've got or can borrow a random orbital sander it will sand down beautifully, or a cork sanding block will be OK with a bit of care.

If the paper is worn through try sealing the underlying plaster and/or painting it before sanding.

Polyfilla is plaster based AIUI, so much harder than the surrounding paper.

cheers, Pete.