Content

• Steps
• Warning

Do you ever stay in the bathroom, changing room or private area with mirrors and feel like someone is looking at you? You can check if the mirror is bidirectional by observing its installation, and using a few simple tricks to determine if the back is a harmless wall or not. You may have heard of nail checks before, but there are also more accurate ways to identify two-dimensional mirrors.

Steps

Part 1 of 2: Considering the location

1. 

   Observe how to install the mirror. The mirror is hung on the wall or attached to the wall. If it's a hanging mirror, try to look behind to see if it's a real wall. If the mirror is attached to the wall, chances are it is a two-way mirror, which must be attached to the wall, not hung. That way the person standing on the other side of the wall can observe the person looking in the mirror.
   • The two-way mirror is a sheet of glass covered with a material called a micro pane. If you are on the scanned side you will see your reflection, but if you stand on the untreated side you will see through the other side like window glass.
   • If you check to see that the back is a wall, then most likely it is just a common one-way mirror.

2. 

   
   
   Check the light. Look around the room and determine if it is brighter than usual. If so, there is a high chance of it being a two-dimensional mirror. If the light is dimmer in the room and you cannot immediately see yourself in the mirror, then it is a normal mirror.
   • For a two-dimensional mirror to work, the light on the mirror side must be 10 times brighter than the light on the other side of the mirror. If the light is dimmer, the person standing on the reflective side can see through the observation room.

3. 

   
   
   Consider the location. If you are in a public place and in an area that needs privacy like the toilet, a two-way mirror is unusual and illegal. On the other hand, two-way mirrors are often used by law enforcement agencies. For example, an interrogation room, when allowing a suspect to line up for witnesses to identify.
   • The use of two-way mirrors is binding on privacy and by law. Most US states have passed additional laws to prevent the use of two-way mirrors in restrooms, changing rooms, bathrooms, fitting rooms and hotels. If an area has two-way surveillance mirrors, they must have notice signs to the residents.
   • Many places like gas stations will use metal mirrors because the glass mirrors are easily broken by the driver. If the mirror you are wondering about is metal, it is not a two-way mirror.
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Part 2 of 2: Examination of the mirror

1. 

   
   
   Observe carefully through the mirror. Bring your face close to the mirror, hold your arms around your face to block the light from your eyes, forming a dark tunnel. When you do, if the light in the viewing room on the other side is brighter than yours, you will be able to see through the mirror into the other room.

2. 

   Illuminate the light in the mirror. If you're still not convinced, turn off all the lights, then shine the flashlight in the mirror (you can flash your phone). If it is a two-dimensional mirror, the room beyond the mirror can be illuminated and you will see it.

3. 

   Sound test. Tap on the face of the mirror to make enough noise. A normal mirror will make a shallow, dull sound because behind it is only a wall. The two-way mirror will give an open, echoing sound because the other side is empty space for the observer.
   • The sound you knock against a two-dimensional mirror can also be clearer and sharper than the dull cloudiness of a normal one-way mirror.

4. 

   Do a nail test. Although this is not completely accurate, you can still use your fingernail to identify single- and double-sided faces. Just point your finger at the mirror. If it is a double layer mirror, ie a normal one-way mirror, your finger cannot touch the reflection but there will be a line separating it, which is the second layer of glass inserted on the mirror coating. If you touch the mirror and you can touch the reflection, it is because there is no glass lining there. It is very rare to use such single-layer mirrors so if there is, there is a high chance it is for a special reason and it is a two-dimensional mirror. Double-layer mirrors are normal mirrors you use every day.
   • Due to variations of lighting and manufactured materials, it is sometimes also difficult to determine if you are touching the reflection.You might think you're touching the monolayer mirror when you're not.
   • In addition, a two-dimensional mirror can be a normal double-layer mirror. Where the light determination methods and mirror installation already tell you it is a two-dimensional mirror, you no longer need to listen to the nail test.

5. 

   Consider extreme measures like breaking a mirror. If it is a normal mirror it will crack and you can see behind it is the lining protecting the mirror or wall. If it was a two-way mirror, then behind it would be a room. You should only consider this when you feel threatened or in danger. Breaking the mirror can injure and endanger your safety. advertisement

Warning

• There is no absolute way to verify. Just a small gap in the wall is enough for a hidden camera with fisheye lenses. You will never see through but see a room, or knock and hear echoes, or hold your hand up to see something through a mirror. Even if it was just an ordinary mirror, there were many other places where surveillance equipment could be hidden.
• Remember that not everyone has the urge to peek enough to risk all sorts of troubles. Except for the owner of a retail store to prevent petty theft by both customers and employees, or as new government agencies need a two-way mirror.