What’s in your ink?

You’ve planned out the ultimate tattoo — the art, the colors, where on your body you’ll get it done, the shop, the artist. You’ve put a lot of thought into this image that will forever adorn you, but there’s one factor you can’t be sure of: What’s in the ink going under your skin?

That’s a question Assistant Professor of Chemistry John Swierk hopes to answer. He and his team are working to understand the molecular composition of tattoo inks to provide knowledge to artists and consumers.

“The tattoo ink market is not regulated in any way and there’s no oversight being offered, unless there’s some kind of issue with bacterial contamination,” Swierk says. “So our goal is to empower the people who are doing the tattoos, to empower the people who are getting tattoos, to have an understanding of what is going into these inks.”

Swierk’s team is documenting its data at whatsinmyink.com. The site lists tattoo ink brands and their products, with information about the composition of each ink and the potential risks.

If someone has an allergy to nickel, they should avoid a tattoo ink that contains the substance, he points out. Allergies are a real consideration; many people have reported serious allergies to tattoo inks, which are difficult to remove and can cause years of irritation, he says.

“In the long run, we also hope that this data can become kind of a snapshot because if you develop a problem with a tattoo ink, it can take time for an allergic reaction to manifest,” he explains. “In the short run, we want to inform consumers.”

Kelli Moseman is a PhD student in Swierk’s research group. Her main responsibilities revolve around analyzing the different ingredients that are listed on the tattoo ink bottles.

“I do a lot of analytical chemistry to identify and quantify these different components, using techniques such as nuclear magnetic resonance spectroscopy, microwave acid digestion and thermogravimetric analysis [that determines a material’s thermal stability],” Moseman says. “So far, we have found that the ingredients list on the back of the ink bottles is not usually complete. Either no ingredients are listed or they are missing some of the components that we have identified.”

Tattoo inks are typically made of a mixture of solid particles of pigment, molecular dyes and binders suspended in a water solution. The color comes from light either being reflected from or absorbed by the particles and dyes.

Swierk’s lab focuses on the intersection of light and chemistry, particularly how light can drive chemical reactions.

“If you find the right wavelength of light, you can cause a molecule to undergo some kind of photochemistry. That might involve a transformation that changes the color or causes the molecule to decompose,” he says. “Are there any risks or hazards that are generated when the tattoo ink is exposed to light and potentially undergoes some kind of decomposition to give you new molecules? Maybe what you start with is perfectly safe, but the process of photochemical breakdown generates something that maybe isn’t safe. We don’t know the answer to that question at the moment, and that’s one of the things that my group is trying to understand.”

Whatever data they do collect, Swierk is quick to note that he and his group are not “anti-tattoo.” They just want people to be informed.

“Our interest isn’t so much in trying to convince people to not get tattoos,” Swierk says. “Our interest is trying to empower those people, so you understand if you’re going to get a tattoo lasered off or if you’re going to get a tattoo, that you go into it with the best knowledge and understanding we can give you.”