In 2018, The Pink Stuff was little more than a home cleaning product with a cute name. “The miracle cleaning paste,” as it said on every container, was sold by just two retail chains in Britain. At a factory near Birmingham, The Pink Stuff line operated for about two hours every month. That was plenty.

“It was a brand with a lot of uses,” said Henrik Pade, a managing director at Star Brands, the company behind the product. “But nobody used it.”

Actually, The Pink Stuff — which is, yes, bubble-gum pink — had some fans. One of them was Sophie Hinchliffe, a then-28-year-old hairdresser in Essex, about 30 miles east of London. Ms. Hinchliffe had learned about The Pink Stuff on Instagram, naturally, and had started posting daily videos to her then-new account, @mrshinchhome. All the videos were snippets of her nonstop campaign to spiff up the home she had just moved into with her husband.

There was Mrs. Hinch, as she called herself, using a toothbrush to scrub the grout in her bathroom. Here she was polishing her candlesticks. If it were stained, The Pink Stuff would clean it, she told her small but growing audience. Don’t buy new tiles, she advised. Spend 99 pence and restore the old ones. She recommended other brands, too. The Pink Stuff was simply a favorite.

“Hinchers,” as her devotees soon christened themselves, found something meditative and satisfying about watching a chatty, glamorous and yet relatable woman eradicate grime. And these people weren’t just gawkers. They were seeking product tips from the scrubber in chief.

By the time that “hinching” became a verb — defined as “to vigorously clean” — in Britain, The Pink Stuff’s days of obscurity were over. Stores that carried it found customers waiting for restocking carts to roll by so they could snag all the little tubs they needed. Or more.

“I was like, ‘Guys, what have you done? I can’t get hold of any!’” Ms. Hinchliffe said in a video interview. “Then The Pink Stuff got in touch and said, ‘Would you like us to send you some?’ And that’s when I learned about the whole influencer world.”

Ms. Hinchliffe, who has 4.8 million followers on Instagram, never jumped to TikTok — “I struggle to keep up with one platform,” she explained — but The Pink Stuff did. Pink Stuff-related videos have been viewed more than two billion times on TikTok, Star Brands says.

The Viral Bump

The Pink Stuff joins a jumble of once obscure products that have been transformed by the internet, and TikTok in particular. It’s a roster that includes the Hoan Bagel Guillotine, the Stanley tumbler and Carhartt beanies, to name just three. Sales bumps attained through online glory can be fleeting, though. Just because a new product is hoisted aboard the viral train — look, it’s the Dash Mini Waffle Maker! — doesn’t mean it will stay there.

According to Star Brands, which began tracking online mentions of The Pink Stuff a year and a half ago, the hashtags have consistently been viewed by roughly 20 million people every week. Sales have quadrupled since 2018 to about $125 million a year, a modest sum compared with giants in this space, like Clorox, which has annual revenues that exceed $7 billion. But nobody at the company’s headquarters in Leeds thought this number possible a few years ago. The factory now runs three Pink Stuff lines, all day long, with a work force that has more than doubled. The product is now sold in 55 countries and available at Walmart, Home Depot and Amazon.

“We don’t spend money on traditional advertising,” Mr. Pade said. “It’s fully viral. Which is a little scary because we haven’t got any control over the message about our brand.”

Marketing experts say that puts The Pink Stuff in a precarious spot. When the fortunes of a formerly unknown product are made by social media, they are at the mercy of forces that can be monitored but not managed.

“The goal should be loyalty, not virality,” said Marina Cooley, a professor in the practice of marketing at Emory University. “Virality is dangerous because it’s fleeting, there’s no stickiness to it. People are excited by the first interaction and then look for the next viral thing.”

The original version of The Pink Stuff launched in 1931. It was every bit as pink as it is today, but bore a decidedly less charming name, Chemico Bath and Household Cleaner, and came in a gray glass jar. By 1948, it was packaged in a pink tin, though it was not until 1995 that the manufacturer fully leaned into the product’s color by adopting its current name. New owners took over Star Brands in 2018, hoping to breathe new life into a few cleaning products. They soon hired the brand’s first in-house social media guru, but the sales needle barely budged until the Mrs. Hinch phenomenon began. The company did not reach out to her until well after she’d developed a following. (They offered her free product, but did not pay her for her endorsement.) The whole thing was happenstance. “You can’t plan to go viral,” Mr. Pade said.

Welcome to #CleanTok

As TikTok grew in popularity, Pink Stuff hashtags became part of #CleanTok, or videos that offer tips, tricks and hacks for the sanitation minded. For several years, it’s been one of the platform’s most resilient niches. To date, there have been roughly 110 billion global views of #CleanTok videos, way ahead of #BeautyTok, at 78 billion global views, according to figures provided by TikTok to Unilever.

A typical #CleanTok video features a so-called “cleanfluencer” — some have more than one million followers — working over a sink, or a pan, or a floor, with a particular cleaner and a particular brush. There are usually before and after images, which make these little vignettes a cross between a commercial and an episode of “Law & Order.” They start with a mess and end with a verdict.

“People find it very soothing,” said Lori Williamson, a cleanfluencer who lives in Toronto and recently racked up more than one million views on a video of her cleaning a hair dryer. “Others say it’s motivating.”

She has partnered with 20 brands, though not The Pink Stuff. She learned about it after it was showcased by Mrs. Hinch but before Star Brands ramped up production, which it did in 2020, and purchased a North American distributor, which it did last year.

“It cost $24 to get it,” Ms. Williamson said. “I was so upset.” (It now costs $4.99 on Amazon and is carried in about 30,000 stores around the world.)

How well does The Pink Stuff work? The vast majority of #CleanTok videos are triumphal tales — The Pink Stuff vanquishing every surface of a bathroom, The Pink Stuff reviving a sneaker. Someone in the comments section invariably asks the same question: Does the pink stuff have a name?

There are Pink Stuff failures, too, like pots that remain covered in baked-on grime. One woman warned that The Pink Stuff didn’t fix the scratches on her car, something it isn’t designed to do.

Wirecutter, a consumer review site owned by The New York Times Company, tested The Pink Stuff and concluded that it was good but overhyped.

A Happily-Ever-After Ending

Ms. Hinchliffe started posting videos to manage her anxiety and to help her connect with others, like herself, who were more comfortable at home than mixing with strangers.

“If I found myself starting to get a little bit anxious or panicky for no reason, I would pick up my mop, or I’d get my Hoover, or my cloth, and I would just put the music on and go for it,” she said. “And I’d find that I was no longer focusing on what I was worrying about.”

With her fame, Penguin Random House came calling. Her debut, “Hinch Yourself Happy” from 2019, was the first of a handful of books to reach No. 1 on The Sunday Times’s best-seller list. Brands called, too. Ms. Hinchliffe now works with Procter & Gamble to create Mrs. Hinch versions of cleaning products. Once a year, she travels to the company’s offices in Brussels and fine-tunes their scents. Today, she lives in a five-bedroom farmhouse with her husband and children, along with a dog, chickens and alpacas.

A happily-ever-after ending is harder to predict for The Pink Stuff. It no longer depends on Mrs. Hinch, but if the goal is to create a lasting product, Star Brands has some work ahead of it, said Professor Cooley of Emory University.

“It doesn’t sound like there’s an adult in the room, steering the cult,” she said. “There needs to be someone dictating a communication strategy — working with influencers, working with retailers.”

Four years ago, when Gen Zers discovered Vaseline, she noted, Unilever created a handful of new versions of the 152-year-old petroleum jelly, like Vaseline Gluta-Hya, which it touted as 10 times “more glow-giving” for skin than vitamin C. In other words, the company catered to the new crowd.

Mr. Pade of Star Brands says The Pink Stuff engages with influencers, but there is no sense in trying to control them. The tub design has been tweaked a little, and the company operates a four-person social media team to keep an eye on hashtags and produce in-house posts. Otherwise, The Pink Stuff convoy drives itself. Supporters of the brand can spot sponsored content a mile away, Mr. Pade said, and they don’t like it.

“Interest will drop off at some stage because the popularity of cleaning will be overtaken by sex or drugs,” he predicted. “But once people hear about The Pink Stuff through social media, they try it.”

Audio produced by Tally Abecassis.