A ceiling that is not part of the structural framework of a building

Plasterboard started to be used for ceilings around the mid 1960s.

Artex is a water-based covering, usually used to decorate ceilings

Plastering is a very difficult process and plasterers train for a long while to get a good, smooth flat surface. Plaster, in scratch coat and top coat form, goes off very quickly. You do not get a lot of time to work with it and get it smooth.