skim over platered wall

Old walls been wallpapered, removed wallpaper hopeing to paint but walls need reskiming. in order to paint walls.

What do you use to coat the walls before skiming please?
Also how do you stop the finished plater from cracking { hair line cracks appeared some weeks later}
PLEASE HELP????????????????

Answer

PVA glue - which is available everywhere. You mix the PVA up with water in the ratio of 1 part PVA to 4 parts water (very approximately - you don't have to be exact) and paint this evenly over the whole wall. This ensures it bonds properly and seals the surface to ensure the old walls do not pull the moisture out of the new plaster you're applying too quickly.

The plaster should remain workable on the wall for at least 30 minutes. If it dries to quickly then cracking can result. Often old lime plastered walls that have residue of old wallpaper adhesive and paint can be very porous and requires 2 coats of PVA to be applied, but only if it is a dense, solid finish. If the surface is powdery or a limewash then a specialist primer will be needed. If using PVA the first coat should be diluted sufficiently to ensure it absorbed into the wall. You can either apply the PVA just before you apply the skim or days before.

If you have a lot to do then you can use a roller to apply the PVA.