The best plaster depends on the intended purpose. Bonding plaster should be used on smooth surfaces, hard wall plaster is a great base coat, and tough coat plaster should be put on last because it is the most durable .
It is possible to plaster over paint, but precautions have to be taken. The paint should first be inspected to make sure it is in good condition with no peeling or cracking. If there is damaged paint, it should be sanded off before putting on plaster.
Plaster is used as a protective layer over drywall to prevent water and condensation seeping into the wood and causing mould and rot. It is also used to make sure the surface is completely smooth before putting up wallpaper or paint.
Plaster shaped in decorative ways is called carved plaster, or plasterwork. For decorations, a more durable plaster is used to cope with being shaped at odd angles and being more exposed to bumps and weathering.
Gypsum is preferred for walls because it has a smooth finish and doesn’t crack as easily. Its versatility and longevity makes it ideal for many different applications and is the go to type for plasterers.