Street artist Joos is perhaps best known for works that resemble ribbons of dissolving color, or paint that’s been pressure washed and left blooms of pigment behind.

“It’s like, is it a shadow? Is it a silhouette? What is it? I think … he gets a kick out of tricking people, and making people take a second look at something,” said Robert Herguth, who profiled the artist last year.

The distinctive graffiti caught the eye of Curious City listener Judy Glaser, who spotted the sprays of color on utility boxes on Milwaukee Ave. She wanted to know who created them, and why.

Unlike many Chicago street artists, Joos came to the medium later in life, first picking up a spray paint can in his 30s. It wasn’t an easy journey to get where he is today — but it’s one that may have saved his life.

On a recent Friday afternoon, Joos got set up under the CTA Blue Line tracks at Milwaukee Ave. and Wolcott St. His backpack was full of spray paint cans and nozzles, and he also had a phone with a reference design. He was there to meet up with a street artist who goes by Stuck — a longtime friend of his. Each year, the two return to the same spot to collaborate on a piece.

Joos, who’s originally from central Illinois and is in his early 40s, started making street art less than a decade ago. He became a regular at Campus, a streetwear store and art space that served as a members-only supply shop for graffiti artists in Chicago.

There, he connected with other street artists for the first time and could purchase spray paint, which was — and still is — illegal to sell in the city. He also got to practice making large-scale pieces on a CTA train replica created out of plywood specifically for artists to practice on.

Though plenty of people consider graffiti to be an art form, the city considers it vandalism. Joos knows this well, having covertly created works in CTA stations, on utility boxes and across other city-owned infrastructure.

Joos scouts sites well in advance, paying attention to foot traffic and police presence in the area. “The street is unpredictable,” he said. “So you gotta study the street a lot.”

When he works on larger projects, Joos doesn’t have the advantage of working solely under the cover of darkness. In those cases he says the trick, for him, is to act like he’s not doing anything wrong. “You show up, six or seven in the morning, and … act like you’re supposed to be there,” he explained.

Normally, paint comes out of a spray can in the shape of a cone. Joos holds his cans to the side, only allowing part of the paint spray to touch the surface. That technique, called “side spraying,” is what he uses to create his signature plumes that adorn utility boxes and wheat paste posters across the city.

“It creates a hard edge and then a fade on the other side,” Joos explained. “… You can use it to make shading. But by itself it looks awesome. And on black surfaces, it looks the best.”

If Chicago is an art museum, the Logan Square neighborhood is Joos’s gallery. His work can be seen all over the city but is particularly concentrated on the Northwest Side.

For Joos, street art was originally an outlet that helped him recover from drug addiction.

“Graffiti is full of broken people, myself included,” Joos said.

“It’s like a harm-reduction type of technique for [avoiding] doing drugs,” he explained. “I get that same kind of rush. It’s dopamine … a really alive feeling.”

Though he occasionally creates works for galleries or does commissioned pieces, Joos says he never wants graffiti to feel like a job. He needs that adrenaline.

One thing that sets Joos apart is that he’s colorblind. This has created some mix-ups for him in the past — like when he mistakenly ordered dozens of paint cans in the wrong color.

Unsanctioned street art, like Joos creates, is inherently ephemeral. Sometimes, if he creates a piece on an abandoned building or one whose owner couldn’t care less, it might stay up for years. But other times, if the building owner puts in a removal request, it’ll be “buffed” out by the city almost immediately.

“The next-day buff humbles you,” Joos said. “You spend all night working on something that’s gone the next day.”

He tries not to let it bother him. “You can either get mad about it,” he said, “or you can go do something else.”

Joe DeCeault is a senior audio producer at WBEZ. Follow him @joedeceault