How much light a surface reflects like a mirror rather than scattering it, from flat matt to high gloss.
Measured in gloss units with a glossmeter at a set angle (commonly 20°, 60° or 85°, chosen by how glossy the surface is), relative to a polished black glass reference. Higher gloss concentrates surface reflection into the highlight, so the colour seen away from it looks deeper and more saturated.
Gloss changes how a colour looks without changing its pigment, which is why one colour in two sheens can fail to match.
The same paint in eggshell and in matt reads as two slightly different colours on adjoining walls.
Colour specifications that omit gloss level leave room for a visible mismatch even when the pigment is identical.
The CIE describes gloss as the mode of appearance in which reflected highlights seem to sit on a surface. A glossmeter puts a number on it by shining light at a fixed angle and measuring what leaves at the mirror angle, in gloss units referenced to a polished glass standard. Three angles are used under ISO 2813 and ASTM D523: 60° for most surfaces, 20° when the 60° reading is above about 70 units and 85° when it is below about 10. A reading is only comparable with another taken at the same angle.
| Finish | Looks like | CIELAB L* | CIELAB chroma |
|---|---|---|---|
| Matte / flat #383888 | #383888 | 28.0 | 51.3 |
| Satin / eggshell #272783 | #272783 | 22.0 | 60.3 |
| Gloss, seen away from the highlight #03037e | #03037e | 13.2 | 77.9 |
About 4% of the light striking a paint film bounces off its top surface without picking up any colour. A matt surface scatters that white light towards the viewer and the navy reads at L* 28.0. A gloss surface sends it off in one direction, and away from that highlight the same pigment reads at L* 13.2, 14.8 units darker.
How this was calculated: Colourwise's surface-finish model: the Fresnel reflection for a refractive index of 1.5 is added to the body colour #000080 in proportion to how much of it each finish scatters towards the viewer. The proportions are illustrative, not glossmeter readings.
Walls are in matt emulsion and the woodwork in gloss, both tinted to the same colour reference.
The woodwork looks a darker, stronger colour than the walls, and the difference is largest for deep shades. Where the two are meant to read as one colour, the gloss needs to be a touch lighter or the sheen levels brought closer.
A scuffed or polished patch appears on a uniformly coloured surface.
It is taken for fading or staining and the surface is repainted, when only the gloss changed. Rubbed matt paint turns shiny and weathered gloss turns dull, and each alters the apparent colour without touching the pigment.