How Do Erasers Erase?

Erasers lift our mistakes right off the page, but it's not magic - it's the microscopic physics of stickiness.

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I’m Cristen, this is BrainStuff, and there are plenty of things I’d like to erase: The box of pizza rolls I ate yesterday; ever watching “Sex & the City Part 2”; and every single Willy Wonka meme. Unfortunately, a lot of marks in this world are permanent. But not so with pencil marks.

Yes, the humble pencil – or not-so-humble, as the case may be.

Pencil lead isn’t actually lead at all. (So no, you can’t get lead poisoning from a pencil wound.) It’s made from graphite, which is a soft mineral made up of flaky, atom-thin layers of crystalline carbon. Ever since the 1790s, that graphite has been mixed with clay to achieve different pencil lead hardnesses.

As you write or draw, flakes of this clay-and-graphite mix cling to the fibers that make up your piece of paper. The fibers have a huge surface area that catches lots of flakes, and the flakes will gladly stick around for decades if they’re not disturbed.

But erasers can lift those flakes right off the page by virtue of being stickier than the paper fibers. It’s as simple as that. Since the flakes are just hanging onto the paper (not unlike thousands of tiny clay-and-graphite kittens, just hangin’ in there), anything stickier than paper can lift them off.

In fact, the earliest erasers, going back to at least the 1500s, were just bread. Slightly moistened and balled up bread.

By the 1800s, people were using erasers made from natural rubber, which is harvested in the form of latex from certain trees, which excrete it to discourage plant-eating insects. (The name “rubber” actually comes from one chemist’s observation, circa 1770, that this tree latex stuff is great when used to “rub out” pencil marks. Rub-er.)

But because natural latex rubber can be expensive and some people are allergic to it, modern erasers are almost always made from synthetic, petroleum-based rubber like polyvinyl chloride.

Your standard pink eraser has bits of pumice added to make it more abrasive, which is a cheap way to help dislodge flakes of graphite from paper fibers. Fancier erasers are made from super-sticky soft vinyl that absorbs the graphite and is more gentle on your paper.

And magic erasers work on a similar principle: Instead of being literally sticky, they contain rigid microstructures that trap dirt. But if you’re ever without one, give your standard pink eraser a try – they’re effective on way more than just pencil marks.

SOURCES:

[adnandeva]

I was taking my usual chemistry lecture about close packing in solids and out of nowhere, the thought of how erasers work hit me 😂

[MaoRuiqi]

You remind me of my first international-experience, many decades ago, while in a library, a young Chinese girl, unknown to me, asks me if i had a rubber for her to borrow. Flustered i shrugged my shoulders, not knowing what to say. The person next to me, however, having overheard her question, politely hands her a big, pink rubber eraser.

[RussDnB]

I woke up wondering this today. No idea why. Absolutely no idea why. Thank you for the knowledge :)

[BrainStuffShow]

Erasers lift our mistakes right off the page, but it's not magic - it's the microscopic physics of stickiness.

[Master_Therion]

I would erase all erasers, then everyone will have to live with their mistakes. MUAHAHAHA It's all part of my play to take over the world.

[matnojje]

I would like to erase my student debts

[donkehr]

I always figured they worked by removing the fibers in the paper. I know I've had to start more than one algebra homework assignment because of holes in my paper. You could always tell which parts of which problems gave me the most trouble because the parts that weren't a hole would be significantly thinner than the rest of the paper.

Then again, maybe I just pressed too hard when I erased.

[Gameplayery]

i would erase that 1:57 "condom" remarque

[rocrzts]

1:02! Haha: the quick brown fox jumps over the lazy dog. LMFAO

[Paul_Wetor]

Way back in the 1960s, a classmate had a transparent green eraser that had a shiny surface. He could even stick it to the underside of the school desk. I have yet to find an eraser like that.

[typograf]

I recall a certain type of eraser used for removing ink from acetate or like materials. It contains minuscle drops of solvent, that are ripped open when it is used.

[quwyn]

thank you i been wondering about that for a while

[potatosaladd]

why do some erasers erase better and why are some pencils harder to erase?

[CristianEscudero]

Neat channel, keep it up the good work.

And btw, your eyes are amazing. I almost forgot to pay attention to the content of the video.

[audreydeatherage]

thank god for the internet. this question popped and my head and was very much bothering me.

lately ive been constantly learning random information like this, its fun.

[kikihappycat]

LOL willy wonka memes trueeee. i didn't know cristen was in this as well as stuff mom never told you. she's hilarious.

[aaronangel]

I would erase embarrassing moments from my memory (junior high)

[bland]

There's 3 standard type of erasers the white ones which is usually rectangle shaped the pink ones with points on its small side and those ones you see on the back of a wood pencils that are really cheap extremely light pink color and don't get rid of the led at all just make a black mark on the paper

[aapjew]

Ok, that was really funny xD and now I know how erasers work! Good job :)

[mudithmanu]

Thanks, learned a lot about rubber trees.