The visible range of the human eye is between 400 and 700 nm (0.4 - 0.7mµ). However, the spectral distribution of sunlight goes far beyond that range. Humans cannot see in the UV and near infrared region (NIR), which extends from 700-2500 nm). In the near infrared r the light energy absorbed by dark surfaces is converted into thermal energy, which heats up the material and then radiates as warmth.
Materials and surfaces which employ the TFL COOL TEC do not absorb rays in the NIR but reflect them instead. As a consequence especially darker surfaces will heat up much less.
Each colour, dye and pigment has its own reflective properties. In general, white is strongly reflective in the visible area as well as in the NIR, while black is absorptive in both cases. Thanks to the TFL COOL TEC black is only absorptive in the visible area, i.e. it appears black, while in the NIR it is reflective, i.e. white.
Since the light energy is now reflected in the NIR, less heat energy is formed and the leather remains cooler. The temperature difference between standard and cool leather increases with the duration and intensity of sun exposure. In extreme cases the temperature difference can be more than 25°C
Let´s have a look at a simple example:
Water is transparent, ice and snow, however, are white - why? Through the formation of crystals inside them snow and ice reflect light diffusely and it therefore appears white. The fibre structure of the skin also leads to a diffuse reflection of light, which means that light energy is not absorbed and therefore not transformed into heat. Dyes and / or pigments normally destroy this characteristic of leather. However, with the special dyes and pigments of the TFL COOL TEC these characteristics are preserved in the NIR. Crust leather dyed with the special SELLA® COOL dyes reflects the NIR rays which even pass through the finish coat when the unique RODA® COOL pigments are used.
When we look at cool and standard leather through a camera fitted with a red filter to remove the visible range of 400 - 700 nm and make the near infrared visible to the human eye, cool leather appears white and standard leather black.