Page 29 - Chapter 3 - Fundamentals of Laser/IPL Hair Removal

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Chapter 3 – Fundamentals of Laser/IPL Hair Removal 1st Edition
Figure 4 - Skin colour depends on the concentration of melanin
One of the major problems with the Fitzpatrick Scale is that it is too simplistic! A person may receive a significant dose of ultraviolet light and induce a tan. Their skin colour may appear to change from an SC2 to SC4, while their Fitzpatrick remains the same – your Fitzpatrick cannot change, but your epidermal colour can. In fact, your skin colour changes across your body with wide variations in some people, even without a tan!
Note that the hair colour (melanin concentration) is not always directly related to the skin colour. Many Japanese people exhibit ‘pale’ skin colour whilst owning very dark hair!
Based on the Steve Jacques definition of skin colour, we calculated the absorption curves for the six ‘Skin Colours’ – see Table 4 (SC1 to SC6), since the amount of absorption of laser/IPL light energy depends very strongly on the concentration of melanin in the skin.
The chart in Figure 5 shows how strongly melanin absorbs various wavelengths of light for six different skin colours. It is clear that the lower wavelengths (blue and green) are very strongly absorbed compared with the red wavelengths (everything above 600nm).
________________________________________________________________________ 29 Chapter 3 Laser/IPL Hair Removal
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