Combing is the drawing of narrow, parallel grooves into a still-fresh layer using a comb or notched trowel. In construction the term is used in two ways: combing mortar or tile adhesive, and combing wet paint to imitate a wood grain.
Combing mortar and tile adhesive
When tiling, the adhesive is first spread flat onto the substrate and then combed through with a notched trowel. This creates even ridges in the adhesive. It has two benefits:
- Better adhesion — the tile is pressed into the fresh combed bed, allowing air to escape and creating good contact
- An even adhesive layer — the tiles sit nicely flat and at a uniform height
The size of the trowel notches determines the thickness of the adhesive layer. Large or heavy tiles need a coarser trowel (larger notches); small tiles need a finer one. Rule of thumb: after the tile is pressed down, the adhesive should cover the entire back of the tile.
Combing paint (wood grain imitation)
In decorative painting, a special comb or serrated scraper is dragged through wet paint or glaze so that the pattern of a wood grain appears. This allows a cheaper substrate to look like a more expensive timber. The technique is related to marbling (imitating marble) and is carried out by decorative painters.
Related terms
- Mortar
- Adhesive
- Tile
- Adhesion
- Decoration
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