Doorstop

Based on Wikipedia: Doorstop

The Humble Device That Harry Houdini Trusted With His Life

In 1906, the world's most famous escape artist published a curious little book called The Right Way to Do Wrong. Among Harry Houdini's recommendations for keeping burglars at bay? A simple wooden wedge jammed under your door at night. The man who could escape from handcuffs, straitjackets, and locked water tanks believed that when it came to keeping unwanted visitors out, sometimes the simplest solution was the best one.

The doorstop is one of those objects so commonplace that we barely notice it exists. Yet it solves a problem as old as doors themselves: how do you keep a swinging barrier exactly where you want it?

What Exactly Is a Doorstop?

The term actually covers several different devices, all united by their relationship to doors but otherwise quite distinct in how they work.

The most intuitive kind is what you probably picture first: something that holds a door open. This might be a wedge kicked under the door's edge, a heavy object placed in the door's path, or a hinged bar attached to the door itself that swings down to grip the floor.

But doorstops also work in the opposite direction. Wall-mounted bumpers and floor-mounted posts prevent doors from swinging open too far, protecting walls from the destructive impact of swinging doorknobs. Without these, you end up with crescent-shaped dents in your drywall, or worse, holes punched clean through.

There's also a third, less visible kind: a thin strip of wood built right into the door frame that prevents the door from swinging through to the other side when closed. This is why when you shut a door, it stops flush with the frame rather than continuing through. Most people never think about this feature until they encounter a door without one.

A Brief History of Stopping Doors

People have been propping doors open for as long as there have been doors, but the formally manufactured doorstop emerged in eighteenth-century Europe. By the early 1800s, European manufacturers were producing them in quantity, and by mid-century, production had largely shifted to the United States.

The official inventor of the doorstop, at least as far as patent records are concerned, was an American named Osburn Dorsey. In 1878, Dorsey received United States Patent number 210,764 for his doorstop design. It became his most famous invention, though the historical record on Dorsey himself remains frustratingly thin.

The gap between when people started making doorstops commercially and when someone received a patent for one tells an interesting story about the nature of invention. For decades, manufacturers produced doorstops without anyone claiming ownership of the concept. Dorsey's patent likely covered a specific design improvement rather than the doorstop as a category—you cannot, after all, patent the idea of putting something heavy in front of a door.

The Wedge: Physics in Miniature

The classic doorstop wedge is a small lesson in mechanical physics. Made from wood, rubber, fabric, plastic, or other materials, it works through a clever exploitation of geometry and friction.

When you kick a wedge under a door, the door's weight presses down on the wedge's sloped surface. This creates what physicists call a normal force—the wedge pushes back against the door. But here's the elegant part: as the door tries to move forward (toward closing), it would have to travel up the wedge's slope. The harder the door pushes, the more firmly the wedge grips the floor.

The result is that the door essentially locks itself in place. The same force that would normally swing it closed instead increases the friction holding the wedge stationary. It's a beautiful piece of passive engineering—no moving parts, no power source, just geometry doing work.

The Brick and Its Toxic Cousin

Before manufactured doorstops became widely available, people improvised. The most straightforward solution was simply placing something heavy in the door's path. Bricks were popular. So were large stones, heavy bookends, and whatever else happened to be both dense and available.

For decades, lead bricks were particularly prized for this purpose when people could get their hands on them. Lead is extremely dense—about eleven times heavier than water—which means a small lead brick provides significant stopping power. Lead is also soft enough that it won't scratch floors or damage doors.

We now know, of course, that lead is profoundly toxic to humans. It accumulates in the body, damages the nervous system, and is particularly harmful to children. The use of lead bricks as doorstops has been strongly discouraged, though one suspects there are still a few lurking in old buildings, their danger unrecognized by the people who step over them daily.

The Door-Mounted Solution

Some doorstops attach directly to the door rather than sitting on the floor. The traditional design is a short metal bar with a rubber cap, mounted on a small hinge near the door's bottom edge, on the side opposite the door's main hinges.

To hold a door open, you swing this bar down until the rubber tip contacts the floor. When you try to close the door, it pivots slightly around the rubber tip, which increases the downward pressure on that tip, which increases friction, which holds the door more firmly. Like the wedge, it's a self-reinforcing system.

To release the door, you push it slightly more open—counterintuitive, but this briefly lifts the rubber tip off the floor, allowing you to flip the bar back up.

A more modern variation uses magnets. A magnet attached to the door's edge latches onto either another magnet or a magnetic metal plate mounted on the wall or a small hub on the floor. The magnet must be calibrated carefully: strong enough to hold the door against drafts and casual bumps, but weak enough that a person can easily pull the door free when needed.

Protecting Walls From Doors

Every door is a potential battering ram. Opened enthusiastically, it can drive its knob straight into the wall behind it, or slam its edge into nearby surfaces. Over time, even gentle use takes a toll.

Wall-protecting doorstops come in several forms. The simplest is a rubber dome or cylinder screwed into the wall at the height where the doorknob would strike. These are sometimes called wall bumpers. When the door swings open, the knob hits the rubber instead of punching through the drywall.

Floor-mounted versions serve the same purpose but intercept the door's bottom edge before the knob reaches the wall. These can be simple rubber-tipped posts or more elaborate spring mechanisms.

The spring doorstop deserves special mention. Rather than simply absorbing impact, a coiled metal spring (tipped with rubber or plastic to prevent scratching) flexes under pressure, distributing the door's kinetic energy over a longer time period. This reduces peak force and makes the stop gentler on both door and wall. It also produces that distinctive boing sound that has entertained children and annoyed adults for generations.

The Hinge Stop

Sometimes the best place to stop a door isn't at its edge or on the wall, but right in the middle of things. Hinge stops, also called hinge pin doorstops, mount directly to the door's central hinge.

These are particularly useful when you need to protect baseboard molding—the decorative trim that runs along the bottom of walls. A floor-mounted stop might miss the door, or a wall-mounted stop might be at the wrong height. But a stop built into the hinge can catch the door at precisely the right angle, regardless of the room's specific geometry.

Language and Regional Variation

English is full of words that shift meaning depending on where you are, and doorstop is one of them.

In several British dialects—particularly in the southwest, northeast, and northwest of England—the word doorstop means something entirely different: it's cognate with doorstep, the raised threshold at a door's base. Both words share a root in door and stoop, which in older English referred to a step or platform.

So when a speaker of certain British dialects mentions a doorstop, they might mean the step you stand on while waiting for someone to answer, not the wedge that holds the door open. Context usually clarifies, but the potential for confusion is real.

The Doorstop as Security Device

Houdini wasn't wrong about the security applications. A simple wedge jammed under a door is surprisingly effective at preventing forced entry, at least of the pushing variety. The physics work just as well in reverse: the harder an intruder pushes, the more firmly the wedge grips.

Modern security-minded variations exist. Portable door security bars brace against the floor and the doorknob, making it nearly impossible to force the door inward. Some hotel travelers carry compact wedge alarms that shriek when disturbed. The principle remains the same: use geometry and friction to turn an attacker's force against them.

A Metaphor in Waiting

The doorstop has wandered into our language as a metaphor, most notably in publishing. A doorstop book—or doorstopper—is one so thick and heavy it could literally prop open a door. The term is usually affectionate rather than pejorative, suggesting a satisfyingly substantial read rather than unnecessary bloat.

There's something fitting about this metaphorical migration. The doorstop is an object defined entirely by its relationship to something else. It has no function without a door. A doorstop sitting in an open field is just a wedge or a brick or a rubber dome. Only in context does it become a doorstop.

Books, too, exist in relationship. A text without a reader is just paper and ink. The doorstop book promises a relationship that will last—hundreds of pages, dozens of hours, a substantial commitment of attention.

The Invisible Made Visible

What makes the doorstop interesting isn't its complexity—it's one of the simplest devices imaginable—but its invisibility. It solves a problem so thoroughly that we forget the problem exists.

Doors want to swing. Hinges are designed to enable exactly this movement. Every door in your home or office is constantly being acted upon by air pressure differentials, settling foundations, and the simple fact that true vertical is rare in human construction. Without doorstops, doors would drift and slam, drift and slam, all day long.

Instead, they stay where we put them. We take this for granted so completely that we only notice when it fails—when a wedge slips, when a wall bumper falls off, when a door we expected to stay open swings shut on our hands as we carry groceries through.

The doorstop is a tiny piece of solved problem, so successful that its success has rendered it invisible. There's a lesson in that, maybe. The best solutions aren't the ones we admire. They're the ones we forget to think about at all.