Float and Set
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.
Float and set requires a plasterer who is much more highly skilled than someone who can only skim a plasterboard because it requires the undercoat material to be made level with a straight edge normally up to a maximum thickness of no more than 25mm,Float and set is also a lot harder work due to the constant mixing required.
The advantages of Float and set are that it can give much greater sound density than plasterboards and it is an excellent insulator.