How do erasers manage to remove pencil marks?

In today's digital age, you may not give much thought to pencils or erasers anymore. While the iconic No. 2 pencil and the SAT have a deeply embedded history, pencils are seldom used outside of standardized testing nowadays. Despite our digital obsession, Americans still use over 2 billion pencils each year [source: Lunsford].

Despite what many believe, pencils never contained lead, not since Roman scribes used papyrus to write -- that's a common myth. So, if you happen to nibble on a pencil, you don’t need to worry about lead poisoning (though it’s still not an excuse to chew on a No. 2). Today’s pencils are crafted from graphite, water, and clay (which binds the materials), a formula developed by Nicolas-Jacques Conté in 1795 [source: Ritter]. Erasers weren’t even attached to pencils until about a century later. It's this humble companion of the pencil, the eraser, that we're focusing on here.

Erasers remove pencil marks by lifting the graphite from the paper you’ve written on. As you write, the graphite particles from your pencil adhere to the paper’s fibers. The science behind it: Modern erasers are typically crafted from synthetic rubber compounds derived from petroleum, such as polyvinyl chloride (unlike the natural latex rubbers that were once used, which could cause allergic reactions). The particles within the eraser are stickier than the paper, so the graphite clings to the eraser instead. Some erasers have a greater adhesive power, absorbing more graphite and providing a cleaner, less abrasive outcome.

Surprisingly, one of the earliest erasers used was just moist bread. Let’s take a moment to explore how far erasers have advanced since those days of using stale bread.

Can erasers be used to remove graphite, ink ... and even scuff marks?

With a single pencil, you can write roughly 45,000 words, and inevitably, a few mistakes will be made. And with those mistakes, you’ll need erasers—and some are more effective than others.

For instance, pencil erasers (also known as plug erasers) and the typical pink school erasers are quite similar—while they do the job, they tend to be among the worst when it comes to causing smudges, leaving behind eraser debris, and even tearing or damaging the paper. As you rub an eraser across the page, it begins to break down—some of this will help remove the graphite, but some will need to be brushed or blown away. This tougher rubber may require more effort to achieve the desired effect. Softer rubber erasers need less force and friction, making them gentler on paper. For example, white vinyl erasers erase more smoothly than the standard pink ones due to their softer vinyl construction. Kneaded erasers, which can be shaped by hand, are one of the least abrasive options for erasing graphite, charcoal, and lead. Because they’re sticky enough to collect graphite without friction, they leave no smudges, debris, or tears behind.

Erasers are good for more than just erasing pencil scribbles. Do you remember erasable-ink pens? While they’re not as commonly used today as they were in the 1980s, erasable ink products are still available. These inks contain liquid rubber cement, which allows them to adhere to an eraser if erased within 10 hours of writing (after that, the rubber sets and can no longer be erased). Magic erasers can remove marks from various surfaces, but don't forget to test your standard pink pencil eraser on scuffs as well. You may be surprised at its ability to erase much more than just pencil marks.