How to sand Plaster Walls

This is required because plaster absorbs undercoats at different rates and because there is a large selection of differing quality of undercoats on the market, results in different absorption rates and thus a variation in roughness to the plaster surface.

The better the quality of undercoat, the easier the sanding of the walls, the cheaper the undercoat, the more sanding required and therefore a thinner and more transparent undercoat applied.