Aluminium window colours and finishes

How powder coating actually works

The frame is degreased, chromated or pre-treated, then electrostatically sprayed with dry polyester powder and cured in an oven at around 200°C. The powder fuses into a continuous film about 60–80 microns thick. It is not paint and it does not peel like paint.

The two quality marks worth knowing are Qualicoat and, on coastal sites, Qualicoat Seaside. Seaside grade uses a heavier pre-treatment specifically to resist salt corrosion — on a house within a mile or two of the sea, specifying it is the difference between a finish that lasts decades and one that starts to chalk and pit in a few years.

The colours people actually order

• Anthracite grey — RAL 7016By some distance the UK's most-ordered aluminium window colour. Reads dark grey, almost charcoal, and works on both period brick and render.
• Jet black — RAL 9005The Crittall look. Very strong contrast on white render and light brick.
• Matt black — RAL 9005 mattSame colour, no sheen. Much more forgiving of dust and rain marks than gloss.
• Traffic white — RAL 9016For like-for-like replacement where the rest of the elevation is white.
• Dual colourAnthracite outside, white or a warm grey inside. Costs a little more because the frame is coated twice, but it is the standard answer when the exterior needs to be dark and the interior needs to be light.