How Does a Mirror Work?


When you look into a mirror, you see your own image and your surroundings reflected back at you. But how many times have you tried to look at the mirror itself, and question how it works?

mirror reflection

If the answer is at least once, know you’re not alone. To figure out how a mirror works, it’s best to begin with how it’s made.

Making a Mirror

We’ve come a long way since water was the only medium through which to see a reflection. In ancient times, mirrors were made from expensive metals such as bronze and silver.

Now, mirrors are most often made by covering flat glass with a reflective coating, such as silver. Glass provides a solid base for mirrors due to its smooth surface and rigidity. Plus, it’s relatively easy to make.

The glass used must be polished, and without imperfections. Special techniques are used to make curved mirrors.

The first step in the process is cutting the glass to shape and size, which can vary greatly depending on application. Once the glass is the correct shape, size and smoothness, the reflective coating is applied in an evaporator, or large vacuum chamber. The metal is heated to the point that it evaporates, depositing a coating onto the glass surface.

Types of Mirrors

There are several types of mirrors in use around the world.

  • Plane mirrors – These are mirrors with a flat, reflective surface. Plane mirrors reflect an image proportionally. This type of mirror is used most commonly in bathrooms and bedrooms to reflect a person’s image. It can also be used to make a room appear larger and brighter.
  • Convex mirrors – These are spherical mirrors that bulge out, like the bottom of a spoon, distorting the image by making it appear smaller. Convex mirrors are often used for automotive side mirrors to allow drivers to see a greater area behind them.
  • Concave mirrors – These are spherical mirrors that curve inward, like the top of a spoon. The make an image appear larger and are often used for security and medical purposes, telescopes and behind car headlights to focus and brighten the light.
  • Two-way mirrors – These mirrors have a lightly reflective coating on one side of the glass. The mirror will look like normal glass if the amount of light is the same on both sides of the glass, but will appear as a mirror to people on the brighter side if one side is bright and one is dark. A similar phenomenon occurs when you look outside of a window at night. You can’t see out very well but people can see you easily.

Types of Reflection

  • Specular reflection – A highly-polished surface such as a man-made mirror is able to create a specular, or precise, reflection that appears to be an inverted version of the actual object being reflected. The light bounces off the mirror straight back in the same direction it just came from.
  • Diffuse reflection – Water causes a fuzzy reflection because it is not perfectly smooth like a man-made mirror. The light does not bounce off the water precisely but scatters, bouncing off the water from the same angles it hit the uneven water. This results in a blurred reflection.
city reflection in water
Diffuse reflection in water.

The Science of Reflection

Light is energy. When that energy hits an object is can pass through the object, be reflected or be absorbed. The amount of energy remains the same no matter the outcome. Mirrors reflect light energy. Initially, the atoms that make up the metallic coating absorb the energy, but they are not able to maintain equilibrium and become unstable, resulting in the light energy being expelled.

Most people believe that when they look into a mirror, it laterally inverts their image but if mirrors invert horizontally, why don’t they invert vertically, causing that person’s image to appear upside down? If you write a non-symmetric letter on clear plastic and hold that up to a mirror, the letter will appear normal to you, not inverted in any direction. That’s because the mirror reflects light back the same way it receives it. If you wear a shirt with words on it and stand in front of a mirror, the words on the reflected shirt will appear inverted. That’s because the shirt is facing away from you while you’re wearing it. If you held that same shirt in your hands and it magically became transparent except for the words, the words’ reflection would appear normal to you in a mirror.

However, that doesn’t mean that mirrors don’t invert an object’s reflection at all. They do. Rather than inverting left to right or up and down, mirrors invert a reflection perpendicularly. If you touch a business card to a mirror so that the back of the card is parallel with the ground and the left side of the card is touching the mirror, the text will appear inverted.

Transcription of How to Choose the Perfect Mirror for Your Home Video

Daniel:
So Dustin, we’re here at your shop in Waco, Texas and we’re taking a look at some mirrors today. Now this is a really big mirror. Where would something like this go? Is this commercial or residential.

Dustin:
This is residential. You know, consumers are getting a lot bigger and crazier with mirrors. They’re putting them in a lot more places and getting more creative. And I think that’s what we like in our industry. We like creative customers. So this mirror actually goes in a master bath that has massive ceilings; open vault ceilings. And it really is going to open the bathroom up for the client.

Daniel:
Awesome. Yeah, anytime you put a mirror in a space it makes it look so much bigger. This could also probably be used for a home gym too.

Dustin:
For sure yeah, workout areas. You’d be surprised how many people are putting large mirrors in their entryways to open that space up. I don’t think there’s a place in a house now that you cannot not put a mirror.

Daniel:
Yeah, for sure. And mirrors come in all shapes and sizes. I mean, you can go from a mirror this big to a mirror this big and anywhere in between.

Dustin:
Yeah, I think that’s a common misconception. I think consumers typically think that mirrors come in whatever size they see at the store, right? Because it’s a plate glass, because it’s able to be cut, we can literally cut them to any size. Including cutting holes in the middle of them to mount televisions through them or electrical switches or outlets. You name it, and we can get pretty custom with these things.

Daniel:
Yeah, for sure. Well let’s go take a look at some frames.

Dustin:
Awesome.

Daniel:
Alright Dustin, so we just finished talking about all the different shapes and sizes that can be cut from a mirror. But when it comes to finishing off the edge, what options does the customer have there?

Dustin:
So customers have a lot of options. You can get a true bevel on a mirror, which is where the edge of this mirror has been run through a machine and it tapers off and puts a really nice finish on. That can also become a more expensive process. But even adding a beveled mirror strip to the edge of a mirror finishes off a mirror really nicely. This can also be used at joints for a big mirror wall where the two mirrors come together. In addition to that, we have a ton of companies out there that are making these amazing finished off frames. The way this works is you put your full cut mirror at any shape, at any size, on the wall. And this is actually an adhesion process that literally just adheres over the face of the mirror. Slide it over just a shade to cover the edge, and you have a beautiful framed mirror right on your wall.

Daniel:
Super simple. And there obviously plenty of options to pick from as far as what you want from your style there.

Dustin:
Sure. It goes from any color to as ornate as you can think. You also find companies now, especially in our day and age that are actually making custom frames. We even include frames, like these steel frames that allow the mirror to set in, that really finish out nice. And we can also do these in any size.

Transcription of What a Mirror Looks Like When it Breaks Video

Daniel: Alright, so Dustin we’re here today to break some glass with you!

Dustin: Right. This is a good time, right?

Daniel: Yea, absolutely. What do we have here?

Dustin: So this is quarter-inch mirror. This is basically standard mirror that’s used in almost any residential and/or commercial application. It’s a quarter-inch annealed glass, which basically means plate glass. It’s not a safety product. It’s got a coating on the back that makes it reflective. But for all intensive purposes, that’s a piece of clear glass when we start.

Daniel: So what we want to do is we’re going to break this glass. We want to take a look at kind of how it breaks, and tell people how, in the clean up process, what to watch out for and that sort of thing.

Dustin: For sure. I’m going to let you grab that wrench and do the swinging and I’m going to step out of here for a minute.

Daniel: So yea, as you can see, I mean, this is really sharp right here. Lots of jagged pieces down below. But, they are big pieces for the most part.

Dustin: For the most part. You’ll get a lot of shaving, so there will be some small pieces. There’s really no great way to do this but put shoes on, probably find rubber gloves if you’ve got them. Pick the large pieces up, get them in a box. If you put them in a bag obviously they’re going to rip through. And then do some serious sweeping after the fact.

Daniel: Yea, for sure!

More Information on Glass and Mirrors

If you’re interested in learning more about mirrors and other types of glass, check out the Glass.com Info Center.

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Jordan Scott

By Jordan Scott

Jordan Scott serves as the editorial assistant for USGlass Magazine. She has a background as a reporter for Tennessee’s Tullahoma News and associate producer for ABC2’s “Good Morning Maryland.” Jordan studied English and international studies at Virginia Tech where she earned her Bachelor of Fine Arts degree.

Jordan is a voracious reader and has an extensive book collection. She is a black belt in Tae Kwon Do but jokes that she has now also earned her black belt in “attempting” to go to the gym. Jordan loves to travel and learn languages. When not abroad, she enjoys exploring new restaurants in her local Washington D.C. area.


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