Different applications using translucent polycarbonate sheeting call for varying levels of light transmission. With different colours these levels change.Not only does the natural (or visible) light level vary, but the amount of solar energy(heat) also varies.
Polycarbonate is a thermoplastic with a high degree of clarity. Therefore the direct transmission of solar energy is considerably higher than that of a diffused panel. Consideration for the appropriate colour should therefore be carefully weighed up.The diagram below depicts the approximate transmission of the various wavelengths of the light spectrum for a clear PC sheet.
More than 70 % of the heating effect of the sun is carried between 350 and 800 nanometres (generally, the visible light spectrum) and we can see that these wavelengths are generously transmitted through a clear polycarbonate sheet – more than 85%

Heat Stop is an innovative development in polycarbonate translucent roof sheeting. This product effectively eliminates 60% of the radiated heat of the sun, resulting in a cool shaded environment. Heat Stop is a polycarbonate profiled extrusion, manufactured in South Africa, which has a co-extruded layer of UV stabilized surface protection on the weather side. Microscopic
reflective particles are incorporated in the core material which creates the silver colour and the reflective qualities of the product.
If an application for a translucent roof sheet or skylight requires a minimum heat build-up under the natural light panel – Leland Industries offers a polycarbonate solution. It should be remembered, however, that a lower level of light transmission is achieved with Heat Stop. The appropriate surface area of translucent roof sheets must, therefore, be used to achieve the required interior light levels. Heat Stop offers the following properties:
• All the excellent physical properties of polycarbonate.
• UV surface protection on the weather side.
• 20 % light transmission.
• It is available up to 2.0 mm profiles