What is brush-finished plaster?
Brush finishing is the technique of working plaster or render with a brush while the coat is still damp. The Dutch and German trades call it pinselen and Pinseln, from the German Pinsel, meaning brush.
Depending on the brush, the moment and the movement, the result differs: a lightly keyed surface that helps the next coat bond, a deliberate texture in the finish coat, or — in the glaze technique — a translucent colour wash that follows the texture of the render.
What it is for
- Improving adhesion. A smoothly trowelled base coat is a poor ground for the next layer. Roughening it while damp gives the following coat something to grip. The same purpose as combing or scratching, but at a finer grain.
- Creating texture. In textured and decorative render the brush stroke sets the appearance: straight runs, cross-hatching, or an irregular, cloudy movement.
- Colour effect. With a soft brush and a thin, translucent paint or limewash, colour is worked into and over the texture so the depth of the render reads.
Practical points
- Timing is the whole craft. Too early and the brush tears the mortar open; too late and the stroke no longer takes. Work in bays you can finish within the open time of the mix and keep the joins wet-on-wet.
- One brush per surface. Brush type, bristle thickness and stiffness set the grain. Do not swap halfway across a wall.
- Sort the background first. If the background sucks unevenly, the render dries unevenly and the texture comes out unevenly. Priming is part of the job.
- Make a sample panel. Texture cannot be agreed on paper. Lay up at least half a square metre, let it dry, and judge it under the light the wall will actually sit in.
- Practise on a board first. A brush stroke cannot be undone without reapplying the coat.
Related terms
- Plaster coat
- Textured render
- Primer
- Decorative render
- Finish coat
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