This invention relates to the control of radiant thermal energy and more specifically to highly Thermal Infrared (IR.sub.T) reflective pigments for use in decorative coatings for buildings or other areas where the control of IR.sub.T energy and visual decoration are required. Control of the spread of thermal energy in domestic building through passive techniques reduces energy consumption by reducing reliance on heating in cool environments and cooling air-conditioning in warm environments. A number of paint formulations having low emissivity in the thermal infrared exist which are based on variants of conventional decorative paint fluids. There are a number of problems associated with such formulations such as susceptibility to damages and high emissivity for certain colour pigmentations. The present invention proposes a low emissivity flake (1) for use in a paint formulation which substantially overcomes the problems associated with the prior art.