Why a warm white brightens better than a pure white
The amount of light a wall returns can be measured: it is the light reflectance value, or LRV. A pure white such as Pure White No.1 approaches 90%; a warm white such as Lots Road No.24 or Holland Park No.5 returns 82 to 84% — a difference the eye cannot see. What it can see is the colour of the light returned: blue and grey with a pure white in a sunless room, golden with a warm white. At almost equal reflectance, the room looks brighter because it looks sunlit.
Choosing by room
For a dark bedroom, the pink-undertoned whites — Holbein Chamber No.7, Kensington Rose No.22 — are the gentlest on waking. For a living room or dining room, a stone white such as Whitehall No.9 or St Martins No.37 gives substance under lamps. For a kitchen or hallway, Lots Road No.24 or Lemon Salts No.43 make the missing sun. For the whole house, Holland Park No.5.
The pure-white ceiling trap
The ceiling of a dark room is often its darkest surface — it receives no direct light at all. A pure-white ceiling above warm-white walls will look grey and make the walls look yellow. Paint the ceiling in the same warm white, or in a barely lighter white of the same family: Charterhouse No.4 above Lots Road No.24, Maugham White No.2 above Kensington Rose No.22.
See also our colours for a north-facing living room, which white for a ceiling, our white schemes and all our whites.