Mad about Science: Hagoromo chalk

By Brenden Bobby
Reader Columnist

Have you ever made a purchase that fills you with pride every time you think about it? I’ve made a number of purchases recently that went the other way, where manufacturers seem to be racing to the bottom of the quality chain as fast as they can.

A recent shelf purchase from Amazon came included with resin screws spray-painted chrome to look like metal.

Hagoromo chalk went the other direction, showing that a product that costs 20 times more than its competitors can still reliably sell to a dedicated clientele while being worth every penny. 

The chalk has been praised by instructors throughout the world, particularly in Japan and South Korea. It has a smooth, nearly dustless application along with bright and vibrant colors that match the quality of its basic white chalk line. Anyone who has used Crayola chalk knows how dusty and abrasive it can be. Using Hagoromo, by comparison, is like wielding a paint marker after having used a brick of charcoal to write your entire life.

So what makes this chalk so special? Chemical composition.

Hagoromo is primarily made up of calcium carbonate. Calcium carbonate has a huge variety of uses from medications to paint and even glassmaking. You will most likely recognize it as the chalky substance that gives Tums and other antacids their distinctive mouthfeel. 

Competitors will often use gypsum, which is a soft mineral that is also highly abrasive due to minerals like quartz making up its structure. At its core, this is why Hagoromo chalk simply feels different and seems to glide right onto a blackboard surface. It’s also why Hagoromo chalk erases easily, as gypsum will dig in and scratch the board when an eraser is applied.

Some colors of Hagoromo do incorporate gypsum as part of their pigment, but the other chemical processes in their production are an industry secret.

You may be wondering why anyone would pay 20 times over the nearest competitor for chalk, of all things. Chalk in the digital age seems to be fading into extinction. Actually, the need for chalk by those that use it has risen — maybe not for the masses, but certainly for specialty teachers and professors.

University-level mathematics in the digital age has a tremendous need for specialty chalk. Vibrant colors clearly illustrating different components of an equation and how it translates into a diagram is vital for recorded sessions. Students need to be able to clearly see what the professor is demonstrating, and chalk on a blackboard provides a level of control that a digital pen just can’t muster without some serious fiddling.

What does it look like inside the chalk-making process?

The Sejong Mall production facility in South Korea is relatively small — a far cry from a massive industry manufacturer. It contains a number of specialized machines that were once owned and developed by the previous producer, Hagoromo Bungu, in Japan. 

The first step is a specialized machine that mixes the components into a chalk-dough, much like Playdough or clay. The machine rolls and kneads the dough before letting it rest overnight to allow moisture to escape the mixture. Once it’s ready, it’s fed through a special machine that slices and rolls the dough into chalk sticks. This machine was originally developed to uniformly shape thick ramen noodles for consumption. 

The chalk sticks are then left to dry for another day. If they were heated up at this point, the moisture releasing from inside the sticks would cause them to bend and warp. Moisture on the outside is added after this process to keep them from sticking, as it will evaporate off during the drying process and not warp the interior structure of the stick.

The sticks are fired in a kiln between 160 and 180 degrees Fahrenheit for eight hours before heading off to the next step. Each stick is stamped by a machine using a rubber stamp dipped in ink to brand the chalk. Afterward, they are dipped into a special liquid coating that keeps the dust from sticking to users’ fingers.

The supply of Hagoromo chalk nearly halted completely in 2014, causing a buying panic that mirrored the toilet paper panic during the COVID-19 epidemic. Hagoromo Bungu owner Watanabe Takayasu was suffering from advanced stomach cancer and unable to find a successor to take over his company. He announced that the factory would close and the product would no longer be produced.

South Korean math teacher Shin Hyung Seok, who had been using and importing the chalk through Sejong Mall, contacted Watanabe about buying the machines and carrying on the Hagoromo legacy across the Sea of Japan. Watanabe reluctantly agreed and shared the secret formula for the chalk, ensuring its production would continue after the closure of his company. He sold his machines for pennies on the dollar and allowed for the specialty product to continue production to this day.

Stay curious, 7B.