It is well known that on sunny days dark means hot temperatures, and this generalization influences our colour choices on a daily basis from cars to apparel items such as motorcycle jackets. However, there is much more scientific reasoning behind the “dark-hot” association, related to the absorption and reflection rates of solar radiation outside of the visible
wavelength range of light.
The electromagnetic radiation from the Sun that strikes the Earth consists of radiation in the wavelengths of about 300 nanometres (nm) to 2500 nanometres. The wavelength region below 400 nanometres is called Ultraviolet (UV). The UV region can cause damage to our bodies and skin, and also causes degradation to paints and polymers.
The Visible region, 400 to 700 nanometres, is the area where our eyes are attuned to see light in all its various colours. The final area from 700 to 2500 nanometres is the Infrared (IR) region. These longer wavelengths are invisible to the eye, yet contain about half of the solar energy that strikes the earth. This is shown in the chart below:
These particles are combined with the leather surface to enhance the resistance to abrasion. They are so small that the wearer will not notice any change in the feel or movement of the leather. They are permanently bonded to the leather to enhance the life of the leather article.
Black typically absorbs infrared portions of the spectrum causing it to heat up, whereas white reflects almost all portions of light keeping it cooler.
Nature has already evolved in allowing darker colours to remain cool. A typical example is chlorophyll, which is a dark green colour present in trees, yet can reflect the infrared zone of light.
For something to appear black a colour must absorb practically the entire spectrum of visible light and this includes the infrared zone as well. By using biomimicry concepts of chlorophyll, Packer Leather has co-developed Kool Technology in joint partnership with TFL.
Initially black leathers have been developed although this range has now been expanded to other dark colours (e.g. browns, navys, etc) with additional Research & Development.
By special chemical treatments, the leather remains black to the eye, yet to the infrared zone of light it will appear white. This means that the solar heat will be reflected and thus stay cooler due to a lower surface temperature – in effect imparting a thermal camouflaging technology.
From the chart above it can be seen that the Kool Technology is reflecting a much higher amount of the infrared light compared to the standard black leather. When the leather is subjected to an accelerated test method in the laboratory for measuring surface temperature a distinct difference can be seen as shown in the graph below:
Further research has been completed in the area of motorcycle apparel, especially motorcycling jackets. A jacket was constructed whereby half was made from normal finishing technology and the other half was produced with the Kool technology. This was then subjected to direct midday sunlight (with an ambient air temperature of 34oC) for a 30 minute period and then a thermal image was taken. This has been superimposed onto the base picture of the jacket.
The enhanced image above reveals a significant temperature difference between each side of the jacket. This ultimately translates into a much more comfortable experience for the wearer. In addition this technology will prolong the life of the leather due to reduced heat build up thereby reducing the effects of photo and thermal degradation over time.