The Chalk Market: Where Mathematicians Go to Get the Good Stuff

By Coby McDonald

Filmmaker Kyung Lee never dreamed she’d become a dealer. But bringing her first feature-length documentary to fruition required money she simply didn’t have. What she did have, however, was a direct line to the source of high-quality product and access to exclusive clientele.

Hagoromo chalk is a bit thicker than standard American chalk. It has been called the Rolls Royce of chalk—even the Michael Jordan of chalk.

It all started a year prior when UC Berkeley math professor David Eisenbud visited the University of Tokyo. His host said to him, “You know, we have better chalk than you.” Eisenbud replied, “No you don’t. Chalk is chalk.” When he returned to his office, there was a box of Hagoromo brand chalk waiting for him. The moment he placed a piece of that chalk against a blackboard, felt the smooth action, and saw the crisp, thick line it produced, Eisenbud realized he’d been wrong: There’s chalk, and then there’s Hagoromo.

On his return home he snuck a few sticks into his luggage.

Back in his role as director of the Mathematics Sciences Research Institute (MSRI)—the prestigious “Top Gun” of math perched high in Berkeley hills—he spoke effusively about the chalk to anyone who would listen, lamenting that it couldn’t be obtained in the U.S. One of those who overheard his ravings was Lee, who at the time was editing a film sponsored by MSRI about prime numbers.

While some may have been taken aback by Eisenbud’s enthusiasm for the chalk, it came as no surprise to Lee. Though of Korean descent, she grew up in Japan where Hagoromo chalk was a staple of the classroom. In fact, what surprised Lee was that Americans tolerated the low quality of their domestic product. “The chalk here, people don’t put that much effort into it,” she says.

Lee assured Eisenbud that she could get the chalk, and lots of it.

On her next trip to Japan, she paid a visit to Hagoromo Bungu, the small factory that had produced the chalk since 1965 (an earlier incarnation of the business was destroyed in WWII). There she met with the company president, Takayasu Watanabe, who showed her how the chalk was made. “It’s complete craftsmanship,” she says. “They change the portion of ingredients constantly, like they were experimenting with it. It is a good product.” Watanabe told her that Hagoromo Bungu had never extended its market beyond Japan and Korea, in part because he was uncomfortable doing business in English. Lee left with more than sixty cases of Hagoromo chalk, poised to become the only source for the precious stuff in the United States.

Her first customer was Eisenbud. The rest were mathematicians he sent her way. In America, chalk is cheap. Lee’s went for around $18 a box. Nonetheless, when she kicked off her small operation in 2012, grad students, post docs, and professors from all over the country flocked to her because they had nowhere else to turn to get their fix.

Hagoromo chalk is a bit thicker than standard American chalk. And it’s coated, giving it a slick feel and protecting the fingers from dust. It glides smoothly across the blackboard, producing a consistent line with sharply defined edges. And it’s durable, difficult to snap between the fingers. It has been called the Rolls Royce of chalk—even the Michael Jordan of chalk. The latter analogy implies that the chalk is no mere tool, but itself possesses some kind of power. Indeed, some suggest that Hagoromo gives the user a mental boost, that with the chalk in hand theorems practically write themselves.

Perhaps I should pause for a moment to acknowledge that this all seems crazy. Like Professor Eisenbud once did, you are likely thinking, chalk is chalk. How can something that children use to play tic-tac-toe on the sidewalk inspire such fervent adoration among a group of people whose minds are otherwise occupied with topics of immense complexity?

So, let’s consider for a moment this simple writing implement. Chalk occurs naturally, sometimes in dramatic formations such as the jagged protrusions off the coast of the UK’s Isle of Wight. Chalk deposits formed around 90 million years ago when the calcite shells of a type of plankton called coccolithophores accumulated in vast quantities on sea floors, creating a layer of material known in geology as ooze. Over many millions of years, the ooze was compressed into soft, porous, white rock. Tectonic upheaval thrust the chalk strata up out of the sea, where it was collected by early humans. They found that the crumbly substance left a mark when scraped across a harder surface. They used it to decorate the walls of caves with sketches of wooly mammoths, saber-toothed tigers, and rudimentary geometric symbols.

So when you hold a piece of chalk between your fingers, you’re holding a piece of the geological history of planet earth. And when you write with it, you’re engaging in a tradition stretching back to our primitive ancestors, putting abstractions on the wall to make sense of our world.

And that’s what math is. Sort of.

“Nobody can define [math],” Eisenbud says. “But I would say that it’s the study of abstract relationships between things. It’s a kind of science of analogies. Pure imagination plays a huge role too.” Math is the language of physics, he says, and increasingly it’s the language of biology, information science, and computer technology. “It really informs our world. It’s part of everything.”

It might be surprising that mathematicians still use chalk and blackboards at all. Surely there’s some kind of cutting-edge technology that would suit their needs better. Which brings us to another less obvious element of mathematics: craft.

“Mathematics has a craft aspect, especially in lectures,” he says. “A good mathematics auditorium has six blackboards. A good lecturer can fill them one at a time, systematically, so at the end there’s a whole panorama of what happened. With slide talks, you think your own thought for a minute you’re dead. Because it’s gone.”

If math is a craft, then its tool is the humble calcium carbonate cylinder. Which is why mathematicians get so misty-eyed about Hagoromo, likely the best chalk in the world. Or at least, it was.

In 2015 Hagoromo Bungu announced it would close up shop. Watanabe was having health problems, and his kids didn’t want to take over the chalk business. The word got out, and mathematicians the world over panicked.

“It was a crazy response,” Lee says. Soon she was getting around one hundred requests a day. “I just couldn’t deal with it. I thought, I shouldn’t have done this.”

Eisenbud wasted no time contacting his trusty supplier. He ordered a lifetime supply. “I have a closet full at home,” he says.

If math is a craft, then its tool is the humble calcium carbonate cylinder. Which is why mathema-
ticians get so misty-eyed about Hagoromo.

All that anxiety-fueled amassing of chalk turned out to be unnecessary. A Korean company bought the brand along with its chalk recipe and specialized equipment. The company now sells it on Amazon. At Eisenbud’s direction, MSRI is now in the process of switching over from the brand it formerly stocked to the Korean-produced Hagoromo. “It’s almost indistinguishable [from the old Hagoromo],” he says of the now-Korean product. In fact, he knows of only one person who can tell the difference, a math professor at Stanford named Tadashi Tokieda. “He has very refined senses.”

The wide availability of the chalk has put Lee out of business. But she says she’s happy about that. “I kind of felt guilty about making money off of the chalk, because it’s not like I did anything,” she says. “Anyway, it’s not my passion.”

As for all her former customers, those mathematicians who flooded her inbox with desperate pleas for the good stuff, they can now rejoice that their favorite product is just a click away. But will they? Scarcity drives demand, it is said. Certainly, some of the appeal of Hagoromo arose from the difficulty in acquiring it. Now that any old fool can get a box, will its mystique diminish?

Soon the summer school program at MSRI will begin, and math students from universities from all over the world will be exposed to many of the greatest minds in mathematics—and also, to Hagoromo chalk.

“We’ll be introducing a lot of people to this chalk,” Eisenbud says. “I just hope they don’t take it all with them.”

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Hagoromo chalk is available on 72 pieces for 24 bucks.
Loved the way the chalk story inter-twines with math, its appeal, and virtues. Well said that ‘Math is the language of physics, and increasingly the language of biology, information science, and computer technology’.
So much love for the chalk, but nothing about the boards they are being used on? Are we talking about smoothed slate? Or that black paint that Home Depot foists off as being an instant blackboard. You’ve described the Yin of the chalk, but nothing on the Yang of the board. I sense years of research…
This article is totally rad.
The MIT math department has a ton of this stuff in cabinets as well. Seems to be a cross-national obsession =)
The Chalk is available for the international shipping from Sejong Mall ( for price of 30 $ for 120 pieces and $18 for 72 pieces. For the blackboard, the ceramic enamel blackboard is a fine choice.
Now you tell me. My dissertation would have been waaaaaaaaay better if I had access to this stuff. If you could just come up with a white board pen that doesn’t run out of ink after 10 minutes, you’d really have something.

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