Page 33 - Chapter 3 - Laser/IPL Hair Removal

Chapter 3 – Fundamentals of Laser/IPL Hair Removal 2nd Edition
These numbers indicate how much riskier it is to target darker skins with these lasers/IPLs. Unfortunately, many operators tend to reduce their fluences on darker skins, to minimise any potential damage in the epidermis. While this will help to minimise any damage to the epidermis, it will also reduce the chances of a successful outcome in the treatment of the hair!
The proper way to account for darker skin colours is to apply more skin surface cooling. By doing this, we can maintain the correct fluence for the procedure, whilst also minimising epidermal damage. Remember, we choose the fluence according to the target hair (its depth, to be precise) - not the skin colour!
Note that the melanin absorption coefficients in the hair shafts are significantly higher than in the epidermal basal layer, due to the higher concentrations. This explains why hairs can become hotter than the surrounding tissues, when exposed to the appropriate light energy.
Hair colour & skin colour – contrast – why this is so important
With laser/IPL hair removal we are trying to ‘overheat’ the hair shaft whilst not damaging the surrounding skin tissues. This is, in essence, a balancing act – we want to purposely ‘cook’ the follicles, using light energy, but also protect the skin.
The optimum scenario is when the hair is very dark and the skin is very pale. This is the maximum contrast between the two – a pale skin will absorb very little of the incoming light energy, while the hair should absorb much more. Calculations show that black hair has a melanin concentration up to 20 times that of a pale skin (5%, SC1).
The worst-case scenario is when the skin is dark and the hair is lighter – more energy will be absorbed in the skin, in this scenario, leading to higher temperatures in the epidermis.
High contrast
Low contrast
Dark hair, pale skin
Light hair, dark skin
More absorption in hair Less in the epidermis
Less absorption in hair More in epidermis
Table 6 – The contrast between hair and skin colour is important
To mitigate against any possible unwanted damage we must apply skin surface cooling – this will help to draw out any excess thermal energy and reduce the likelihood of skin damage. See Section 3.3 on ‘The Importance of Proper Skin Cooling’.
________________________________________________________________________ 33 Chapter 3, Ed. 2.0 Laser/IPL Hair Removal
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