trowelling

Trowelling is a finishing technique used in plastering, masonry, and concrete work, in which a trowel is used to apply, level, and smooth a layer of material on a surface. The term covers both manual plastering with hand trowels and the smoothing of freshly laid concrete or mortar. Different trowels are suited to different tasks: a plastering trowel or margin trowel for shaping plaster or mortar on walls and edges, a brick trowel for spreading mortar between bricks, and a steel finishing trowel for smoothing plaster or concrete surfaces; for large slabs, power trowels may be employed.

In plastering, the work typically begins with a rough coat that is allowed to set, followed by one or more finishing coats. After each coat gains sufficient strength, trowelling brings the surface to the required flatness and sheen. Finishing trowels produce a very smooth surface, while edge work uses smaller trowels or margin trowels for details. In concrete finishing, trowelling is done after initial setting to compact and smooth the surface. A steel trowel may be used by hand or mounted on a power trowel for larger areas; final burnishing creates a glossy finish, whereas a broom or texture can be applied for slip resistance.

Quality and timing are important: environmental conditions, mix design, and workmanship affect results. Over-trowelling can trap moisture, create laitance, or cause cracking, while under-trowelling leaves a rough or weak surface. See also plastering, masonry, and concrete finishing.