A year ago, Tom Atkin, a 25-year-old bartender in San Diego, wanted to add to his collection of ink, which already included an owl on his right bicep, an anchor on his chest, and a bouquet of roses surrounding a cross on his left forearm. Atkin walked into his usual tattoo shop to get a little something different. He saw somebody getting a UV tattoo and said why not?

“I decided it would definitely be something different that’d make me stand out,” Atkin says.

Atkin’s tattoo artist inked a blue and black HIM heartagram using a tattoo gun and a UV torch. Atkin says the tattoo is invisible in normal light.

UV tattoos, or black light tattoos, are leaving their mark on the bodies of many millennials these days. Originally popular among the rave culture, UV tattoos have surfaced as a new way to get inked. Nearly invisible in non-UV environments, these tattoos come alive under ultraviolet or black light. However, the newest trend in body art isn’t exactly mainstream.

Black light tattoos have also been popping up all over online forums, Pinterest and YouTube. UV tattoos are particularly popular among 18- to 30-year-old club goers, rockers and tattoo enthusiasts who want to hide their ink, according to tattoo artist Richie from the American Tattoo Society via the ABC News article “Latest Body Art Trend: ‘Invisible’ Tattoos.”

Nearly four-in-ten millennials have a tattoo, according to the Pew Research Center. However, there are no reported statistics for UV tattoos because of its underground popularity. In a survey of the eight most reputable tattoo shops in New York City, none offered UV tattoos.

Because tattoos are so common, UV tattoos give millennials the opportunity to spruce up and edge out their ink. Greg Kulz, tattoo artist at Fura Bodyworks in Castro Valley, CA, is known as the pioneer of UV tattoos, having appeared on “Ripley’s Believe It Or Not” for his homemade UV ink. The 15-year UV tattoo artist says the invisibility factor in normal light is what draws young people to the new trend. “Now you can have tattoos and not be tagged a biker because no one can see them,” the 28-year-old said.

When it comes down to inking a UV tattoo, the process is slightly different than a regular tattoo. Kulz says he still draws up the tattoo and applies it to the skin like any tat. Because UV ink is thinner than normal ink, it’s a slower process that requires a lot of attention to avoid irritating the skin too much. He also has to use a black light while tattooing to make sure it looks correct under black light.

Kulz recommends using white UV ink for the most unnoticeable UV tattoo because it is virtually invisible on light skin tones under normal light.

Anthony, 22, who declined to give his last name, itches for a new tattoo every couple of months since his first tag on his 18th birthday. Word of mouth and the internet introduced him to the world of UV ink. “I ordered some ink and a small ultraviolet torch. I took the ink down to my tattoo artist [at Ink Lined tattoo parlor in Sylvan Lake, Alberta] and said we have to give it a shot,” the Canadian student says.

The successful outcome of Anthony’s white UV koi head tat on his arm amazed him. “After two weeks, it didn’t look like there was anything in that spot but it still glowed. It was quite cool,” he says.

Like any tattoo, UV ink tattoos leave minor scarring from the actual tattooing process itself. With regular tattoos, the scarring isn’t visible because of the colored ink that hides the scarring. Unless the UV ink is used to enhance a regular tattoo, light scars resembling fine tan lines can be seen.

But Anthony doesn’t mind the visible scar. “It doesn’t bother me that a scar can be seen,” he says. “I haven’t had any bad skin reactions, swelling or sickness.”

Overall, Anthony recommends getting a UV tattoo. He says it’s been about six months and the koi head still glows nicely. He even got a small LED UV key ring to show off his ink. “It’s quite a cool party trick. A lot of people are amazed and straight away want one,” he says.

Anthony lucked out when his tattoo artist agreed to use UV ink. Many tattoo artists forgo the use of UV ink in their shops.

Jon Renee, owner of Main Street Tattoos in Urbana, Ohio, refuses to tattoo anyone asking for a black light tattoo. “I’ve always steered clear of the stuff because of safety issues,” the 13-year tattoo vet says.

Such reactions to UV ink may include severe blistering, pain, a burning sensation, and skin rashes, according to livestrong.com.

“I get calls almost daily about ‘glow in the dark’ ink. That stuff just scares me,” Renee says.“I’m not chasing the dollar. I’m in business for the long haul and I care about my customers’ health and safety.”

UV ink is normal tattoo ink mixed with UV-reactive ink. Vendors like Crazy Chameleon Body Art Supply and Skin Candy have been providing UV ink to the public since 1999 in 18 different colors.

Dr. Will Kirby, dermatologist and co-founder of the Dr. TATTOFF laser tattoo removal clinics, doesn’t recommend getting a black light tattoo because he says some of the ink could cause adverse reactions, or worse be cancerous.

UV ink doesn’t contain phosphorous, the carcinogenic ingredient that may cause cancer. However, glow in the dark tattoos, tattoos that only show in complete darkness but not in UV or black light, do contain phosphorous, according to livestrong.com. Whether the phosphorous in glow-in-the-dark inks is cancerous is still unknown.

“First off there’s a big difference between black light and glow in the dark [tattoos]. There are alot of things that glow under black light that aren’t toxic,” Chris Van R, owner of tattoo Tattoo, a tattoo parlor in Queensland, Canada says.

Crazy Chameleon, the best known supplier of UV ink, declined an interview but states on its website that its EverGlow-free UV ink is FDA approved with no preservatives or other additives. Stephen Griffin, tattoo artist at Epic Dermis Tattoo Parlor & Curiosity Shoppe in Plattsburg, NY, finds that hard to believe. “The FDA approved a blacklight reactive ink for marking seafood, not for tattooing. That is where the confusion comes into play, since apparently some people have used this ink for blacklight tattooing thinking that it was FDA approved and therefore safe for human consumption. In reality, it was FDA approved simply for the purpose of stamping fish,” the New York native says.

Seventeen percent of those who get tattoos consider getting them removed, according to the American Academy of Dermatology. However, it’s not that easy for black light tattoos. UV tattoos may be less prominent in normal light, but are much harder to remove off the skin.

Dr. Kirby says only one patient out of every 1,000 patients who come into his office to get a tattoo removed is removing a UV tattoo. He considers freezing tattoos off to be an antiquated process and says the only way to get rid of a regretted UV tattoo is by cutting it off.

So is it worth it to get a UV ink tattoo? Griffin doesn’t think so.

“When in doubt, do without. A cheap party trick is no reason to jeopardize one’s health,” Griffin says.