of years and shows no sign of slowing down.

If you don't have them, chances are your friends

or at least your favorite barista does:

Tattoos.

This week, we're all about ink, so think carefully

about what you want on your body permanently

as we tattoo some knowledge on your brain.

(SPLASH INTRO)

Thousands of years ago, when hipsters of that

era were getting tattoos, many different

ingredients were used for inks.

Different colors came from ground up

natural products like copper, ashes, graphite, tree bark and woad.

Today our inks have evolved, and multiplied.

Tattoo artists use so many different pigments

for colors that if you have two different tattoos

from two different places, there's a chance

that ink in your right arm is made up of

different stuff than that ink in your left arm.

No matter what the ink ingredients are,

it's a straightforward recipe:

A solid pigment creates the color and is suspended in a liquid carrier.

Liquid carriers can include any on or combination of the following:

water, witch hazel, glycerine, propylene,

and alcohols anywhere from ethanol

to vodka to even Listerine.

There's a wide variety pigments ingredients, too.

Here's some of the different forms of black,

brown, red, green, blues, violets and whites.

Why are tattoos permanent?

So as you might know, skin cells live for about

two or three weeks, but tattoos last forever.

And if you've ever thought that tattoo

On your inner lip will disappear after

six months, you're dead wrong.

It will never disappear… trust me…

To explain why tattoos are permanent

here's Rachel Feltman from the Washington Post's Speaking of Science.

Conveniently, she is in the middle of getting a tattoo:

“The tattoo needles, which have ink stuck

between them, are puncturing my skin about 50-3,000 times per minute.

They're going through the epidermis and into the dermis.

They're making holes there and capillary

action is drawing ink down into the dermis.

Now what makes a tattoo permanent is when

my immune system is trying to save me

from all of wounds that I'm suffering from.

Basically, every time the tattoo needle makes

a hole, macrophage cells will start to go

towards the wounds to try to close it up.

And, because the ink is a foreign invader, the

macrophage cells gobble it up to try to get rid of it.

But instead the macrophage cells with bellies full

of ink, get stuck in the gel-matrix in the dermis.

And they stay there pretty much forever, which is why the tattoo stays visible and permanent."

She makes it look so painless.

So when your tattoo is brand new, the ink is in both

the epidermis and the dermis layer of your skin.

But as the skin heals, the wounded epidermal cells

are shed and replaced with new ink-free cells.

This is why your tattoo looks more vibrant before it's done healing.

Your epidermis regenerates in about two to four weeks.

Over time, tattoos will fade as the body's immune

system slowly breaks down the alien pigment

particles and the macrophages take them away to be destroyed.

But generally, the ink will stay with you

for most -- if not all -- of your life.

Trust me.

We'd like to give several shoutouts for people

who've made this episode possible.

First we'd like to thank Fatty's Tattoos and the

very talented Sabrina Elliot for her tattoo work.

We'd also like to thank the Washington Post

and Post TV for working with us on this video.

For more information on tattoos, check our

Claudia Aguirre's article and website.

We've posted the links in the description.

Be sure to like share and subscribe.

If you have any topics you'd like to see us cover,

let us know right down there in comments

or hit us up on Facebook or Twitter.

Thanks for watching.