Week #5: That Tattoo Ink on Your Skin

Most of us are often amazed by a new tattoo someone we know just got or even ourselves'. There's something cool and attractive about those ink that got us hooked? However, tattoos are meant to stay, and do you know why that ink is permanent?

INTRODUCTORY VIDEO

  

Standard YouTube license: Why Are Tattoos Permanent? uploaded by Reactions

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DISCUSSION 

Pigments

Tattoo inks are composed of two elements, pigments and liquid carriers. Pigments are mostly metal salts (NOT vegetable dyes like many would assume). Ink manufactures are not required to reveal the content of the inks they produced, nor the ink is regulated by the US Food and Drug Administration (FDA). The tattoo artists can also create his or her own inks by mixing up dry pigments, and more often than not this too is a secret (for business purpose) and thus the chemical content of tattoo inks can be vague¹. (That's why as mentioned in the video, "ink on your right arm can be made up of different stuffs from ink on left arm"). Therefore, you must choose a reliable shop before heading for a new tat to be safe!

As pigments are to create color, liquid carriers are used to make the pigment evenly distributed on skin, prevent clumping of pigments, and prevent pathogens (bacteria and viruses). Again, tattoo artists can create their own liquid carrier² (using one or a mixture of some examples listed in the video). However, he or she can used pre-dispersed pigments, which are often safer than the "DIY" products of the tattoo artists (although the chemical content is, again, not required to reveal).

Here's to some of the metals, or other substances that create the wanted pigments¹:

Color	Material	Note
Black	Magnetite crystals or Iron (II,III) oxides Carbon Wustite	Black pigments are often made into Indian ink
Brown	Ochre or ocher	Composed of iron (III) oxide (Fe2O3)  mixed with clay with color range from yellow  to deep orange/brown
Red	Cinnabar (HgS) Iron (III) oxide (Fe2O3)  Cadmium red (CdSe)	Iron (III) oxide is often known as "common rust" Cinnabar and cadmium red are highly toxic
Green	Chrome oxide (Cr2O3) Malachite Cu2(CO3)(OH)2	Pigments are often mixtures of other pigments
Blue	Cobalt blue  Lapis lazuli  Azurite	The safest blue and green pigments are copper salts
Violet	Quinacridone (C20H12N2O2)  Carbazole (C12H9N) Manganese ammonium  pyrophosphate (NH4MnP2O7)	Some pigments are photoreactive --> lose color  after extensive exposure to sunlight
Yellow	Chrome yellow (PbCrO4) Cadmium yellow (CdS)  Curcuma yellow (Tumeric)	Yellow pigments are often reactive since more pigments are needed to achieve  desirable color
White (assume the font's  color is  white)	Lead carbonate (PbCO3) Barium sulphate (BaSO4)  Titanium dioxide (TiO2)	White pigment can be used alone (white tattoo  is pretty common now) or to dilute other pigments Titanium dioxide is the least reactive white pigment

*You can tell the number of metal salts present in this table! This is an exhaustive list of chemicals, so if you're curious about any particular one it's easier if you do the research outside to keep this post short and concise.

Tattoo needles and machine

Tattoo needles do NOT shoot ink into your skin, at least in the literal meaning. Tattoo ink is held among multiple needles of the tattoo machine. Once the needles puncture into the skin to the dermis layer, the surface tension and forces that hold the ink together force the ink to seep down into the holes created by the needles³. This effect is referred to as capillary action. Because macrophage cells, cells that are responsible for repairing skin wounds (after needles punctured through the skin), cannot dissolve or dispose ink pigments (since they are alien substances), these cells get stuck in the dermis and stay there forever, causing the ink to be visible on our skin and permanent. Also, newly-tatted skin is wounded, and thus is vulnerable and required special care before healing⁴.

Before you head for a new tattoo (if you're planning to), make sure to read about the health concerns, including but not limited to allergies, infections, granulomas (bumps on skin caused by infection or presence of alien substance), and blood-borne diseases (hep B and hep C). There are many resources online, and you can always ask tattoo artists about your concerns. Responsible artists will provide you with useful information, sometimes even refusing to tat you due to health concerns. If you recentl got a new tattoo, remember to take care of it, because it is a fresh wound!

Applied to Australia, must check for your countries' policies 

Finally, while writing this I remember a rumor of Cristiano Ronaldo, the Portuguese footballer, saying that the reason he did not have any tattoo is because he wants to donate blood annually. I'm not sure if this rumor is true or not (perhaps he has other reasons but he does indeed not have any tattoos). However, you CAN still donate blood even with tattoo, but you have to wait for several months after getting one to donate blood because your blood must be tested for viruses of blood-borne diseases (mentioned above) or antibodies against these diseases, and these antibodies take time to grow.




UPDATE: People are working on tattoo ink that will no longer be permanent!!! This ink is hope to be out into the market by Fall 2017. Check it out at this video!

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Sources
Thumbnail background from Tattoobite
Pigments from UKRZOVNISHCHIMPROM LTD
Tattoo Process from HowStuffWorks (credit on image)
Australian blood donation campaign poster from The Australian Red Cross Blood Service (taken from Young Blood Campaign)
¹ Tattoo Ink Chemistry
² Tattoo Ink Carrier Chemistry
³ Watching a tattoo needle in slow motion reveals the physics of getting inked
⁴ Tattoos and Skin Health
⁵ Tattoos: Understand risks and precautions