Cut-in technique: brushing a sharp paint edge

Cutting in is the painter’s technique of brushing a clean, straight paint edge where a wall meets a different surface, the ceiling, the cornice, skirting, an architrave, a window reveal, or an adjacent colour. It is the brushwork done before or alongside rolling, and it is the single thing that decides whether a paint job reads professional or amateur. A roller cannot reach tight into a junction, so every edge on a job is a cut-in line, and every one of those lines is visible.

The brush and the load

Cutting in is done with an angled (sash) brush, typically 50 to 65mm, the angled tip lets the bristles meet the line cleanly. The brush is loaded about a third to halfway up the bristle, then the excess is tapped off against the inside of the pot, not wiped across the rim (wiping starves the brush and causes a dry, ropey edge).

A loaded-but-not-dripping brush is the whole game: too much paint floods over the line, too little drags and leaves brush marks.

Making the cut

The standard approach is three passes:

Unload a few millimetres back from the line, so the bead of paint sits off the edge.
Run back to the line in a steady, slowing stroke, letting the released paint flow up to the junction.
Drag along the line in one continuous pass, brush at a low angle, using the paint already on the surface rather than fresh-loaded bristle.

The aim is to float the bristle tips along the junction so the paint, not the brush, finds the corner. Short, scrubbing strokes are what produce a wavy line.

The wet edge

Cutting in only works if it blends into the rolled field. The cut-in band must stay wet until the roller laps into it, so the two merge with no visible seam. If the cut-in dries before rolling, the overlap shows as a different sheen or texture, called hatbanding or picture-framing, a border of brushed paint around a rolled centre. Painters manage this by cutting in and rolling one wall at a time rather than cutting in the whole room first.

Common defects (what gets flagged)

Cut-in quality is assessed visually at handover, and raking light across a wall exposes every flaw:

Wavy or crooked line at the wall-to-cornice junction, the classic amateur tell.
Bleed, paint carried onto the ceiling, the trim, glass, or the wrong side of a colour change.
Holidays, missed spots where the brush did not reach the corner.
Brush marks (ropiness), ridges left by a starved or over-worked brush.
Hatbanding / picture-framing, the cut-in band reading a different sheen or texture from the rolled field.

These are the most common painting defects raised at the practical completion inspection, because they sit at eye level on every wall. AS/NZS 2311:2017 Guide to the painting of buildings is the industry reference for paint workmanship; the contract specification and the PCI are what they are actually assessed against.

For a builder

It is a workmanship line, not a materials line. A wavy cut-in is a rectification item; it is on the painter’s labour, not the paint.
Check it in raking light before you sign off. Walk each wall with light skimming across it; cut-in defects vanish under flat light and reappear the moment the sun is low.
Colour changes and dark-over-light are the hard ones. Crisp lines between two colours, or a dark colour cut against white, are where a good painter earns the rate. Hold those edges to a higher bar.

Also known as: cutting in, cut in, cutting-in.

The brush and the load

Making the cut

The wet edge

Common defects (what gets flagged)

For a builder

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