Even if I tried to make them, my tattoos just won’t scrub off in the shower. This is a good thing. I like my tattoos. The reason they’re here to stay involves some fascinating body science. YouTube chemistry channel Reactions delves into the reason behind the  permanence of tattoos in a video published Tuesday that goes under the skin.

The video kicks off with a history lesson. People who are surprised by the popularity of tattoos these days might not realize the skin decorations have been around for thousands of years. While pigments such as copper and tree bark were once the norm, today’s tattoo artists rely on substances including carbon and malachite suspended in a liquid like water or alcohol.

So how does that pigment manage to stay in place? It’s all about the immune response.

Getting a tattoo is like getting a controlled wound. The needle repeatedly enters the skin, depositing ink as it goes. Cells called macrophages show up to eat the invasive pigments and then get stuck in place beneath the epidermis, the top layer of skin. They stay there and so does your tattoo of Grumpy Cat riding Twilight Sparkle.

Via C|NET: Click here to read full story.