Popular colours for radiators vary from generation to generation.
The first radiators installed in public buildings were generally matt black, because it was then believed that a rough black finish allowed heat to pass from the system to the surrounding air quickly.
When well-breeched householders first adopted central heat- ing at the turn of the century they wished to advertise their opulence to friends and so they chose a metallic paint — generally gold — which showed up well against the rather dingy wall coverings of that time. As central heating became more widespread and ceased to excite so much attention, and rooms became smaller in size, a bright colour was deemed to make a room look smaller still and so a colour similar to that on the walls was used in an effort to hide the unit. Psychedelic patterns followed. What will happen in the future is in the lap of the goddess Fashion.
Conservation of fuel is certainly important these days, but so is a pleasing colour. And the fact is that you can use almost any type of paint on your radiators. With the reservation dealt with in appendix 2 in connection with some metallic paints, the colour and texture make only a slight difference to the rate of emission of heat.
If a new radiator comes from a manufacturer shop-primed, clean it after installation with white spirit, touch in any scratches with zinc chromate primer and apply to the whole lot two finishing coats of a household paint. Don’t use an undercoat because it is too highly pigmented to adhere properly. An alternative is a polyurethane paint,though this will not afford the same choice of colour.
Radiators that are not shop-primed should be given a coat of zinc chromate primer all over, followed by two finishing coats of an orthodox or polyurethane paint.
Leave for several days for the paint to harden before turning on the heat. There may then be a slight painty smell, but that will soon disappear.
We have seen that, with certain reservations, colour does not affect heat emission to any marked extent. For all practical purposes, therefore, it is immaterial which you use. Nor does it matter much if the finish is glossy or matt — though a gloss paint is quicker and easier to clean. All light colours will tend to deepen in time, particularly those based on oil and under the influence of heat.
If you wish to use a metallic paint avoid the usual type, the particles of which float to the surface and join up forming a thin continuous sheet of metal which at certain temperatures will lessen heat emission by 15 per cent or more. Choose a gold or silver paintwhose finely milled metallic particles remain enveloped in the medium when dry. The loss of heat will then be negligible. If your radiator has already been painted in a coarse floating pigment type of metallic paint, clean it with white spirit and give two coats of varnish or oil paint or polyurethane, and the heat loss will be restored.