Page 62 - An Introduction to Laser Tattoo Removal

Chapter 2 – Fundamentals of Laser Tattoo Removal v1.0
Suffice to say, that the ‘optimum’ time between treatment sessions appears to be between 12 and 24 weeks! (See later section ‘Time Between Sessions’).
What is ‘frosting’?
Frosting can be caused by two processes in the skin.
The first of these is caused by absorption of laser energy by the melanocytes in the basal layer (between the epidermis and dermis). If these is sufficient absorption then the melanocytes can ‘balloon’ – see photos from McLeod’s thesis). This appears as ‘frosting’. However, this will only occur when the wavelength is absorbed by the melanin. A 1064nm light beam will not induce this effect in lighter-coloured skins simply because it is poorly absorbed by melanin. In darker skins (usually referred to as Fitzpatrick 5 and 6), there may be some evidence of this occurring due to the higher density of melanin in the skin.
It has also been observed that darker- skinned patients have a higher risk of hyper-pigmentation (also known as ‘post inflammatory hyperpigmentation’ – PIHP). This is more likely with the shorter wavelengths (532nm in particular!)
See Mike’s blog post.
Figure 29: These ‘frosting’ spots appear immediately following 532nm laser pulses fired at some tanned, non-tattooed skin. The spot size was 4 mm with a fluence of just under 4 J/cm2. This whitening is created by the melanocytes and melanosomes ‘boiling’ after absorbing some of the laser energy.
The second process is caused by the formation of countless steam bubbles next to the ink particles in tattoos. When these particles absorb laser energy they heat up rapidly, exceeding the threshold for water boiling quite quickly. Steam forms, as a result, which scatters light much more than normal skin. This is observed as ‘frosting’ and only lasts for between 15 and 30 minutes, in most cases. The bubbles soon fill with tissue water thereby returning the scattering to its usual levels.
However, while sometimes this frosting appears as white spots above the tattoo, it doesn’t always! If the ink is not a strong absorber then it may still create some frosting, but this may
________________________________________________________________________ 62
Chapter 2 LEVEL A Laser Tattoo Removal
© The Laser-IPL Guys, 2021