Preparing Plastered Walls for Painting

smbumblebee

Our builder has said that the plastered walls in our new house are really only suitable for wallpaper. He says that we need to prep them ourselves if we just want to paint the walls, which we do.

What do we need to do?

dubtom

A coat of polybond will seal them, it basically stops the first coat of paint from drying into the wall. You should get polybond at any hardware.The best way to apply I find is to roll it on, fairly evenly if you can.

dools

Hi smbumblebee

We have just gotten an old house replastered so are prepping and painting the walls at the minute.

First thing is to make sure to sand the walls down thoroughly to get rid of any 'uneveness' and splashes and to even out any nicks the plasterers may have made. We bought a tool/handle-thing for sanding in the Crown decorator centre like this:
http://multimedia.mmm.com/mws/mediawebserver.dyn?6666660Zjcf6lVs6EVs66SSarc7rrrrQ-

You buy 'screens' like fine mesh to put on it and motion it back and forth across the wall. The dust falls thorugh the mesh.Is better than sandpaper as sandpaper tends to get clogged with plaster dust. We only used sandpaper where there were deep nicks that needed smoothing. Prepare for lots of dust, but is worth prepping the walls properly before painting

We polybonded one room to seal the walls, but found it left steaks that showed through when walls were painted. Instead we used a watery mix of white emulsion (4 measures of paint to 1 measure of water) as first coat (used nomal unwatered paint for second coat)for another 2 rooms. Turned out to be a better job than the polybond in the first room. Does use a good bit of paint though. I would suggest doing a couple of coats with white emulsion before putting any colured paint up. We found the large tub of paint from Atlantic to be very good. I think it's called Maxi Cover and costs €15/16. We have used it on new plaster in 3 houses

D

mad m

Ok first off, if the plastered walls were any good in lets say a smooth finish,there is no need to sand down plastered walls.I would never sand down newly plastered walls,you will score the new plaster all over.Your only meant to de-nib new plaster work.De-nid is running a scraper(wide) along wall and taking the usual splashes of plaster from the plasterers trowel when troweling up.

On the polybond note the main medium in Emulsion paints already have polybond in them.Your only really meant to polybond a wall if you want to seal a wall prior to plastering or applying cement to a hole which has a lot of dust.The poly bond seals the surrounding area.

The emulsion will just sit on top of polybond,the way to do it is get a bucket of emulsion and thin with water it up to 25% or more so that the walls will look like a milky white.This will seal the walls just as good as polybond.

Wertz

PVA on fresh plaster? :rolleyes:

Not this old chestnut again...builders need to stick with building and leave the decorating to someone else. Over the past few years I've come across several self builds where people went off and applied PVA to skimmed walls thinking they were doing right.
In a lot of cases paint will not adhere properly to walls that have been polybonded...it's a shiny, glossy finish and does NOTHING for the coats that come after. Paint will chip and scape off very easily especially sheens.

As mad m said, white matt, thinned out with a quarter volume clean water and applied (thinly) will give a solid base for ANY type of wall paint. This has the added advantage over PVA that it also "kills" the surface, so that your final colour requires less coats. You can add a colour to the initial thinned coat if you like.

...and also like he said don't attempt to sand fresh walls....you'll see the tracks of the grit no matter if you put 20 coats of paint on later; the way to do it is apply your thinned out matt, allow to dry thouroughly and then sand lightly with very fine grade paper or preferably a snading pad/sponge.

Also; "the plastered walls in our new house are really only suitable for wallpaper"
WTF??
In that situation the last thing you want to do with freshly skimmed walls is paste paper on to them....at least size them up properly first...seriously builders, feck off back outside and play with your JCBs...

dools

Maybe our walls were particularly 'nubby', but they deffo needed sanding all over - just a light rub, but a bit of friction where there were marks and nicks in the plaster. Came up perfectly.