On Friday evening, there was a familiar sight near Washington Square: a line snaking out the door of Sweet Charlie's, a shop that opened last spring and helped launch a dessert craze in Philadelphia with ice cream mixed on the spot, poured onto hyper-chilled metal plates, and then scraped off into highly Instagrammable rolls.

But a few blocks away, in Chinatown, are four more rolled ice cream shops, all with the same gimmick. One, called I CE NY, was bustling on Friday; the rest were almost empty.

Yet, the proliferation continues.

As of April 2016, there was not one place to acquire a $7 cup of custom-mixed rolled ice cream in Philadelphia. Now, there are more than a dozen in the region. There's IceMax on South Street and Roly Cow on East Passyunk. In the suburbs, options stretch from Media (Boba Tiki) to Oreland (1°C Iceland) to Collingswood (Arctic Freeze). And within a mere three-block radius not far from Rittenhouse Square, there are three more newcomers this season: Seventh Heaven, yet another Sweet Charlie's, and the first Philadelphia location of New York's 10Below, due to open in the next month or so.

That's a lot of ice cream. Is it too much?

It could well follow the familiar arc of dessert fads past, said longtime Philadelphia restaurant consultant Harris Eckstut. But it's too early to tell.

"On one hand, you have the entertainment value. The Lion King's been on Broadway for 20 years, so there are shows that will last forever. And the numbers work, as far as costs to rent a small space, equipment is not expensive, it doesn't seem like you need a lot of training for staff. From a business aspect, it makes sense," he said. "But will the demand remain?"

The Monkee See, Monkee Do at Sweet Charlie’s
The Monkee See, Monkee Do at Sweet Charlie’s

You wouldn't know it from the openings around Center City, but American ice cream consumption has actually been declining over the last 30 years, and it fell 10 percent just from 2005 to 2014.

And the fickle market for the affordable luxury of trendy, gourmet desserts has laid low others before.

There was the cupcake craze, which peppered Philadelphia with boutique bakeries, like Brown Betty (all three of its locations are closed); mobile vendors like the Buttercream truck (also gone); and outposts of national chain Crumbs, which expanded rapidly in the 2000s and crashed hard by 2014 (six greater Philadelphia locations shut down, plus 60 more nationwide).

Then the frozen yogurt boom swept through town, bringing the opening — and, a few years later, the closing — of self-serve shops Phileo and Sweet Ending, a mobile truck called Gozen Yogurt, and Philadelphia storefronts of international chains such as Tutti Frutti and Red Mango. Even the Walgreens at Broad Street opened a self-serve frozen yogurt bar, perhaps a high-water mark for oversaturation.

Stephen Ngo had no idea he was about to throw down in the rolled ice cream wars when he set out to open Teassert Bar. He had spotted the frozen treat in Las Vegas and New York and figured he'd be the one to bring it to Philadelphia.

"We were the first ones [in Chinatown] to sign the lease, in January 2016, and we ended up being the third shop to open," he said. "Nobody expected so many shops at once."

He tries to stand out with quality ingredients (he said some stores use a powdered ice cream base, but he makes his in-house with just sugar, heavy cream, and milk) and novelties like a sundae of rolled ice cream wrapped in a Hong Kong-style egg waffle.

Ngo is no stranger to competition. He's also in the bubble tea business — he sells it at Teassert Bar and at his three Royal Tea bubble tea trucks, parked at Temple, Penn, and Drexel. That was another dessert glut that swept through Chinatown; at least three bubble tea shops have opened and closed there since 2011.

He figures, looking around at nearby competitors, a similar shakeout might be in store for rolled ice cream.

"I've noticed some places are a little slower than others," he said. "I feel like, sooner or later, a shop might have to close down."

But outside Chinatown, entrepreneurs are betting there's room to grow.

Sweet Charlie's now has four stores, including one in Ocean City, N.J., and another in Rehoboth Beach, Del., and in December, it launched a franchising program that's reached Georgia, Florida, and North Carolina. It's also promoting its new Rittenhouse store with booze-infused flavors, like Kahlúa and rum raisin, to draw evening crowds.

That's impressive growth for a company that began after Cherry Hill 19-year-old Kyle Billig, who started the company with his brother, Jacob, and father, Steven, saw a Facebook video of a Thai street-cart vendor making the instant ice cream and began attempting to replicate it at home using a granite slab and dry ice.

Steven Billig said some customers return several times a week — even though it can mean waiting up to an hour.

"People tell us, 'Our kids want to wait in the line.' They think it's cool. They're taking pictures, texting their friends. So, people expect to wait, and that's sort of the allure."

Sweet Charlie’s often draws lines down the block. Last August, when this photo was taken, people waited more than an hour.
Sweet Charlie’s often draws lines down the block. Last August, when this photo was taken, people waited more than an hour.

He said that when he saw competitors popping up last spring, "at first we were a little concerned how it would affect our business model. But after about a month or two, the demand for our product just kept growing."

The company is expanding cautiously, he said. But they are trying to capitalize on a cultural moment whose longevity is uncertain.

Eckstut said if the quality is good enough, the model might have staying power.

"As an investor, the hesitancy is what the millennials want and will continue to want. I never say never. If the numbers work, maybe it's not just a six-month fad."

Besides, even in dessert fads, there have been survivors.

Philly, after all, still has plenty of frozen yogurt, including the local chain Kiwi Yogurt, which launched in 2009 and had 12 stores at the height of the fro-yo bubble.

Co-owner Matt Mealey watched with some alarm as competitors flooded the market. "Within a five-mile radius, in a place like Collegeville — which isn't really very densely populated — there were four or five other self-serve frozen yogurt shops at one point. Now, there are none besides us. But certainly when those places were opening, things got more challenging."

Now, it has stabilized at eight shops.

Mealey said the lesson for rolled ice cream is: "They're not all going to survive, obviously. It comes down to the operations." He said focusing on friendly customer service, keeping a clean store, and rolling out innovative new flavors, like a vegan, probiotic coconut-milk frozen yogurt, kept Kiwi going.

And, for all the bakery closures, this city is no cupcake desert, either.

Gretchen Fantini, who started the Sweet Box truck amid the cupcake bubble and opened a store on 13th Street in Center City in 2014, figures it never will be.

"Who doesn't love a really good slice of cake?" she said. "If you're really good at it and you work hard, people will come. I'm not scared of hard work. That may be the difference between me and another place. Now I work even more than when I started. I don't have a day off ever. It's very rare."

For now, though, maybe rolled ice cream makers don't even have to be good. While it's novel, the gimmick alone can be enough.

Seventh Heaven, one of the new rolled ice cream shops near Rittenhouse, was empty Sunday afternoon. Then a family of tourists wandered up, clutching Art Museum brochures, and they peered at the window before heading inside.

"I saw this on TV," one said. "I just want to see it for myself."