Hiring a contractor for a plastering job is as age old as the Great Sphinx itself! In the same age range as tile, brick, and cement, plaster is also one of oldest building materials and even ancient Egyptians incorporated plaster into their buildings and pyramid artwork. The plastering work of ancient Egyptians survived for over four thousand years - so you can just imagine how long it will last for you!
Made of sand and lime (gypsum) and of course water, plaster is generally used as a finishing coat on walls (like drywall) and ceilings however you will certainly see plaster in other forms such as art, sculpture, and molding.
Types of Plaster
The different types of plaster that are available are distinguished by the method in which they're made. You may have heard of Plaster of Paris - this plaster is made with gypsum and when dried, it forms a finish that resembles marble. It's when other ingredients are added to this gypsum mixture that new types of plaster are formed.
For example, when clay or lime is added, plaster hardens slower and allows more time to be shaped or molded into place. To enhance the acoustics of a room, an additive may be added which will form air bubbles in the plaster. Plaster made with epoxy resins (or hydrated lime bases) become waterproof and are appropriate for areas around the house that are constantly exposed to wetness (like the shower or kitchen sink).
Plastering Internal Walls
As a wall covering, plaster is applied in two coats. The first coat is called primary coat (although you may hear your contractor refer to it as the scratch coat), and it's intentionally laid on with a rough texture. This roughness helps the second coat stick to the first coat.
The second coat (which again, although you may hear your contractor refer to it as the finish coat) is applied much more smoothly with a trowel. This second coat is what you'll see when you look at an unpainted wall.
Plastering Gets Creative
Today's interior decorators are experimenting with plastering by adding colors and textures to the final coat. Some examples that you might see are Marmorino or Venetian plaster finishes. Both Marmorino and Venetian plastering use different shades or tints of colors to create an interesting look.
Faux plastering attempts to emulate the old worn look of ancient Italy and Rome. During the time of these ancient cultures, plastered walls were worn from age, weather, and probably the effects of numerous wars. Despite the reasons, their appearance gave us a story to tell, and it's this story that modern decorators are attempting to re-tell.
For a really textured look, some interior decorators fuse physical materials into the plaster, like tiny colored stones while others scratch over colored layers of plastering to reveal underling hues. This latter technique is called sgraffito.
Plastering External Walls
Plastering wall in the outside environment is called stucco and stucco can cover tile, brick or even concrete.