Part 1 – To understand laser tattoo removal, we need to understand both tattoos and lasers. Understanding lasers is not as hard as it might seem and understanding tattoos is not as obvious as most people assume. So let’s begin with the tattoo — dont’ skip this part.
By definition, a tattoo is pigment that permanently resides in the dermis, below the epidermis, in the skin. Ink that reaches only the epidermis, the outer most layer of skin, has not penetrated deeply enough and is destined to be sloughed off during the regular process of growth that the skin routinely cycles through. Of course, during a normal tattoo process, much ink will be deposited in the epidermis, just by virtue of the fact that the needle is on the way to the dermis and just passing through.
Veteran tattooees know that this colored epidermis will typically peel off and fall away fairly quickly (a few to several days, much like the skin from a sunburn), leaving the actual tattoo, the pigment in the dermis, behind. Despite the body’s attempts to remove ink molecules from the dermis (scavenger white blood cells called macrophages have a crack at it, carrying them off in lymph fluid to the local lymph node) much of the ink is either captured or ignored, and stays in the dermis. Likewise, ink that travels too deeply stands a higher chance of being carried away, or being accompanied by scarring, as well as difficult to see well. So, in the molecular world of ink, it is pigment molecules in the dermis that make a tattoo.
How does a laser remove pigment molecules from the dermis? In reality–and to be ultra picky–it doesn’t. Instead, it helps the body do what it has always tried to do with the ink, carry it away. A laser is just light, very concentrated light, but just light. When this concentrated light falls on the molecules of pigment, they try to absorb its energy but they simply can’t because it’s too much. Instead, the bonds of the pigment molecules break, nearly vaporizing them, reducing them to smaller sized molecules. As when the tattoo was first applied, the macrophages rush in, scoop up the smaller molecules, and whisk them away.
Does it all sound too good to be true? In fact, there are some details that complicate matters and which cause laser removal clinics to preface their brochures, contracts, and advertisements with cautionary words to the effect that not all tattoos can be removed and that scarring is always a possible side effect. The American Academy of Dermatology says that there is a low risk of scarring when using lasers to remove a tattoo — a 5% chance. Then again, there was a low risk of scarring associated with getting the tattoo in the first place. With any of the old style removal techniques (dermabrasion or surgery), scarring was pretty much expected.