Sanding multifinish thistle before painting

[macadonald]

Hi guys,

My plasterer has now finished applying the render and multifinish skim coat. Looks very nice and smooth. I know I need to leave it to dry out, but I've been told previously, that allthough it has a nice smooth glassy finish, it's worth giving it a light sand to remove any ridges or blemished before painting.

Can anyone advise on how to do this? I assume it's just a case of lightly going over everything? What sand paper? Is a sanding pad useful with a broom handle stuck in the handle? I assume I then wipe the walls down with a wet cloth before painting.

Thanks in advance

 

[Deluks]

Spongebob squarepants for the washdown, several goings over to get the loose plaster dust off.

Some medium grade paper, run your hands all over the wall to seek out the areas that need doing.

 

[macadonald]

Thanks Deluks,

Since I posted the question, I've done a little research on the web. Some 'experts' are suggesting to simply dehead any blemishes and then using a watered down emulsion, apply a 1st coat, which will highlight any problems and then sand these?

I prefer your suggestion of sanding before I paint, but assume the key thing is to remove all of the dust before painting. When you say medium grade paper, what grit. I'd hate to ruin the smooth finish he did.

 

[Richard C]

A newly finished skim should be flat, smooth but not overly polished; it should not need sanding before mist coating. Finishing plaster is not designed to be sanded, sand it too much & you will expose the grain & it will look like suede brushed the wrong way when you paint it & will need additional coats to cover this up. If your plasterer has left you a "glassy" finish, he’s done you no favours at all, over polishing causes problems with paint adhesion; it’s normally done deliberately to **** off the decs, did you upset him in any way . If your spread had done a good job, all you should need is mist coating to highlight any blemishes that need filling; but there shouldn’t be many if any.

In your case, however, lightly sanding (& I mean lightly) the finish plaster to “bust the glaze” he’s left you with is recommended or your paint wont stick at all well. Brush the dust off & mist coat using ordinary cheap matt emulsion, thinned 25-30%; apply 2/3 coats in quick succession, leave to dry overnight; check for any blemishes & fill/sand these & re-mist; apply you chosen finish when fully dry next day.