Skimming means to apply two coats of a type of plaster called a ‘finishing plaster’ over existing walls and ceilings where a PVA glue solution is first applied to allow adhesion of finishing plaster to existing backgrounds,but the plaster can also be applied directly onto new plasterboard surfaces which would not require any PVA preparation

Float and set is a traditional two stage style of plastering. The first stage is a wet undercoat plaster such as sand and cement or browning/bonding which is trowelled onto the walls. When this first stage (the undercoat plaster) has set to a semi firm state, the second stage (the skim coats) can then be applied.

Skimming means to apply two coats of a type of plaster called a ‘finishing plaster’ over existing walls and ceilings where a PVA glue solution is first applied to allow adhesion of finishing plaster to existing backgrounds,but the plaster can also be applied directly onto new plasterboard surfaces which would not require any PVA preparation

If a ceiling or wall is badly damaged it may need plasterboarding over before it can be skimmed with plaster. I professionally install plasterboard for both walls and ceilings with a flush finish that are perfect for skimming.