Colour temperature and CRI: specifying white light that matches

Warm white around 2700–3000 K suits timber, textiles and evening hospitality. Neutral 4000 K suits workspaces, clinics and retail where colour judgement matters. 5000–6500 K reads cooler and is often used where contrast is wanted, but it can flatten warm materials.

Two strips specified as 3000 K can still differ visibly: the actual chromaticity sits inside a bin, and bins vary between production runs.

A 3-step MacAdam bin keeps the colour inside a tight ellipse around the target point. For a single project with several runs in one sightline, the strips should come from the same bin and preferably the same production batch.

If the project has multiple rooms with the same finish, agree whether a slight variation between batches is acceptable before production, not after delivery.

CRI above 90 is a sensible baseline for retail, hospitality and residential details. The average figure hides weak channels, particularly R9 for red, which affects wood, skin and food. Ask for the R9 value when the lit surface is warm-toned.

Not every strip holds its colour point at low output. Constant-voltage strip dimmed by PWM usually keeps the chromaticity; analogue dimming can shift warm. For tunable white, the controller's mixing curve decides whether the transition looks neutral or drifts through pink or green.

Mock up the dimmed state, not only full output. Most complaints about colour appear at the level the space actually uses.