Plaster Textures for the Facade Finishing Layer
Over the hundreds of years they have been in use, the plaster mortars used for facade finishing have changed considerably and gained a new expressive quality: texture.
STONE PLASTER PROCESSING
Cement mortar with rock crumb can be worked into almost any texture:
- stamped textures are created on freshly plastered and floated surfaces using a board patterned with coarse metal wire;
- rough texture with no further processing is obtained by throwing on crumbs of natural stone; once you float the mortar that has begun to set, you get a smooth fine-, medium-, or coarse-grained surface;
- «fine furrow» — the result of scraping the half-hardened plaster layer;
- «fur texture» — working the hardened covering layer with a bush hammer or toothed chisel: a fine-toothed bush hammer gives a fine-grained «pile», large teeth give a coarse-grained one, and a toothed chisel produces a «fur coat» with a very coarse «pile»;
- the «dune» and «torn stone» textures — the result of chipping the hardened mortar with a bush hammer or chisel;
- acid etching yields the same textures in relief, and the plastered, etched surface lasts a very long time.
NB When mixing stone plasters for etching, the coloring agents are not pigments but natural aggregates of different colors — marble chips, anthracite, and brick.
STRUCTURAL PLASTER
Structural plaster is a granular mass with fillers (mineral and stone crumbs, pieces of quartz, an admixture of wood pellets); it can be silicate, mineral, or synthetic. Because the mass consists of "grains" of different sizes, the finished texture can be fine- or coarse-grained: the former looks almost flat, while the latter takes on a distinctive textured surface.
The textures these mortars produce are the bark-beetle structure, the stone-like structure, and the fur texture.
The bark-beetle structure is the result of troweling a fresh plaster layer. The effect of tracks gnawed by a beetle comes from moving the relatively large grains vertically, horizontally, or in a circle — this sets the direction of the grooves.
The stone-like structure has a more uniform structure, so it does not hold dust and dirt. The material is floated in a circular motion and takes on the texture of tightly packed small stones.
The fur texture is applied in an even layer with a trowel, roller, or sprayer. The texture pattern is created by working the still-wet plaster layer with a textured roller.
Structural plaster is sold ready-made in metal cans or buckets (15–25 kg); prices start at $2/kg, and average consumption is 0.35–1.4 kg/m²/mm. The coating withstands temperatures from -58 to +167 °F and lets the wall "breathe".
Decorative thin-layer plasters
The newest trend in stucco work is the use of high-quality thin-layer plasters that deliver both the desired color and texture after troweling. The textures are recognizable:
- uniformly roughened (Edel structure, stone-like structure, goose skin);
- grooved-rough (Rillen structure, bark-beetle structure);
- modeled (Roll structure), which lets you create any pattern you like.
The rough structure is obtained by evenly spraying or smoothing the decorative plaster. Depending on the filler, the finish is either monochrome or multicolored. You can even achieve a completely smooth surface, provided the filler granules are small.
The grooved-rough texture is formed by the tracks of the larger grains; the shape of the grooves is determined by the size and shape of the granules in the mix.
With the modeled (Roll) structure, a thin layer of applied plaster is shaped (imprinted) with tools — a textured roller, a toothed trowel, brooms, or brushes. The tool used and the motions made to create the pattern make each relief unique.
