Tattoos, previously the exclusive realm of sailors, bikers and tough guys, are an increasingly common sight. Modern tattoo practices are the safest and most efficient in history, largely because modern tattooing is as much about medicine as art.
Did You Know?
The modern tattoo machine was developed in the late 1800’s based on an engraving device designed by Thomas Edison.
Let’s start with how tattoos work. Tattooing is fundamentally about depositing ink (or some sort of coloured pigment) just below the surface of the skin. Anybody as absent-minded as myself knows that ink on the outer surface of your skin (like shopping lists scrawled on your hand) washes or wears off easily. Your skin is separated into two distinct layers. The epidermis is on the outside and serves to protect you from the elements. Your epidermis is constantly being renewed, so it makes a very poor location for permanent art like a tattoo.
Did You Know?
The epidermis is thinnest in your eyelids (around 0.5mm thick) and thickest on the soles of your palms and feet (around 1.5mm thick).
Below the epidermis is the dermis, a more stable, much thicker layer of skin that houses some permanent structures such as sweat glands. Tattoo needles puncture into the dermis and deposit ink about 1 mm into this layer. The stability of the dermis is what allows a tattoo to remain there for a lifetime.
What's the ink made up of? The majority of tattoo ink colours are derived from metals: yellow is achieved from the use of cadmium, blue from cobalt, purple and violet from manganese and red from mercury. Other pigments, such as black, are derived from non-metal sources like carbon. The exact formula for each company’s ink tends to be a closely guarded secret within the tattooing industry.
Did You Know?
Contrary to urban legend, MRI or magnetic resonance imaging machines (which generate powerful magnetic fields) will not pull the metal pigments in tattoos out of your skin. At worst they may cause redness and discomfort.
Should you really get a tattoo? A few words of advice before you think about getting a tattoo of your own. Be certain. Having a tattoo removed later in life is an expensive and unpleasant process. Also, do lots of comparison-shopping. Make sure your tattoo parlor has a good reputation and ask to see some pictures of your artist’s previous work. With that in mind, a tattoo can be a celebration of achievements or a meaningful piece of art you carry with you.
For an incredible selection of science-based tattoos, be sure to check out a book called Science Ink by Carl Zimmer.
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Article first published September 23, 2011.