Lighting a painting at home

Warm LEDs, picture lights, the angle to use, and the light to avoid.

A painting is a surface that returns light to your eye; the picture you see is the light in the room, remixed by the pigment. The quality of the light therefore does much of the work of the picture. A good painting can be flattened by a bad bulb and lifted by a good one.

Aim for a warm household white, about 2700 to 3000 kelvin. On a light bulb box this is described as “warm white”; on a stronger box it is described in kelvins. The traditional tungsten filament that lit British rooms for a century sat at about 2700 kelvin, which is why every eye trained on that light reads warmer colour as normal. LEDs that copy this temperature (marked 2700K, 3000K) sit well in a room hung with paintings; a 4000K or 5000K bulb, sold as “daylight” or “cool white”, reads blue on skin and on painted colour, and drains warmth from any picture worked in a Caslon-warmth palette (Anahita’s palette, and many others). If you cannot bring yourself to change every bulb in the house, change the bulbs in the rooms that hang paintings.

Colour rendering matters as much as colour temperature. Look for CRI 90 or above, sometimes marked as Ra 90. CRI stands for colour rendering index, and it measures how faithfully a lamp shows a reference set of colours; a low-CRI bulb (CRI 80, which is common in supermarket LEDs) makes reds muddy and blues flat, however warm the light is. A CRI 95 or 97 lamp costs a pound or two more and holds every pigment a painting depends on.

The angle of the light is the second decision. A picture reads best when the light strikes the surface from above at about 30 degrees to the wall. This washes the whole painting evenly, keeps the frame’s shadow off the picture, and, importantly, keeps the light out of the eye of anyone standing in front of the piece. Ceiling downlights aimed straight down (at 90 degrees to the floor) will glare off the surface and cast the frame’s shadow onto the top of the picture; if the room has fixed downlights, aim them at the wall rather than at the floor, and set the beam a foot or so above the picture, not straight at it.

A picture light is the single most useful accessory for a wall of paintings. A modern LED picture light draws a fraction of a watt, throws almost no heat, and lasts twenty years. Fitted to the wall above the frame, mains-wired or battery, and switched from a nearby lamp switch or a small remote, it lets a painting hold its own in the evening on a wall that would otherwise be dim. Choose a light that is at least three-quarters of the width of the picture (any narrower and the edges fall into shadow), and fit it about 15 to 20 centimetres above the top of the frame, angled down so the beam covers the surface without spilling onto the wall above.

Two forms of light should be kept off the work. Direct sunlight is the slow thief: most pigments fade under ultraviolet light, and a wall that catches an hour of direct sun a day will visibly lighten a painting over a decade. Hang the painting outside the sun beam, or fit a UV-filtering film to the window; a modern film is almost invisible on the glass and stops about 99 percent of the ultraviolet without changing the colour of the light indoors. Halogen picture lights (the older, small bright ones) throw heat and infrared and are worth replacing with a modern LED even if the halogen still works.

For a ceramic mask or relief, the same rules hold with two additions. Light from the side rather than from directly above, because a mask or relief reads its face by the shadow of its own modelling, and a light from above alone kills the modelling by lighting the tops of the ridges as strongly as the hollows. A picture light or a small spot mounted a little to one side of the piece, angled across the face, lets the sculpture come forward. Keep the beam from any incandescent or halogen source off the glaze at close range; heat and ceramic do not agree.

The last note is about the room, not the picture. Lower the ambient light in a room where you look at a painting after dark, and light the painting brighter than the wall around it. A picture in a room lit evenly and dimly is a picture that recedes; a picture that is lit as the focus of the room comes forward and holds. Every gallery does this; every home can do it with one picture light and a dimmer.

Michael, for the studio