What Exactly Is That Chalk Stuff We Spent Our Schooldays Covered In?
Whiteboards are massively more popular these days, and for good reason. They’re easier to read, easier to clean and don’t make a chilling vibration that you feel in your spine when writing on them. In the past, however, the official medium of front-of-class writing was chalk and blackboard. And yet, over the course of a recent meandering conversation, I and others realized that despite the omnipresence of the stuff in our childhood, none of us knew exactly what it was.
I’ve got a general idea about ink. Paper’s a form of cloth, inks are dyes, it all makes sense to me. Chalk is a much stranger beast. All those years of seeing it laying out my homework, gridding out hopscotch games and being tossed in the air by LeBron James, and I still had no idea what the hell was in those white sticks.
Immediately upon Googling (or DuckDuckGoing, to be precise, thanks to the onslaught of A.I. slop and promotional seeding on the former), I received a clue. An entry on chalk from Geology.com informed me that chalk is a completely naturally occurring substance. A specific type of limestone, to be exact. Those little sticks have a truly geological origin, with deposits of chalk still hanging around from the Cretaceous period. It’s inexpensive, plentiful and left marks when dragged across surfaces. Interestingly enough, it seems that blackboards exist to serve chalk's natural abilities, rather than them being introduced as a package deal.
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Of course, there is manufacturing that goes into the schoolroom-ready cylinders we’re familiar with. Some are made of natural chalk and in their oldest form, were fine-powdered chalk mixed with water and clay, rolled, and dried. There’s even differences in ingredients and processes between chalk manufacturers that have led to some chalks becoming legendary among the mathematics community.
Today, there are also synthetic chalks, because there’s synthetic everything. These are made of simple pigments and binder, which is entirely less romantic. I’d much rather imagine that the same chalk kids are learning history with actually witnessed it.
