Have you ever been in a bathroom, dressing room or another private area with a mirror and had that feeling that someone is watching you? You can check to see if a mirror is transparent by observing how it is installed and using a few simple techniques to determine if there’s a wall behind it. You may have heard about the fingernail test but there are more accurate ways to tell if a mirror is two-way or not.
Part 1 of 2: Considering the Location
Observe how the mirror is installed. Notice if the mirror seems to be hanging on the wall or if it’s part of the wall itself. If it appears to be hanging, try to look behind it and see a wall. If the mirror seems to be part of the wall itself, there’s a good chance it’s a two-way mirror, which must be set into the wall rather than hung onto it. That way, people standing on the other side of the wall can observe someone looking in the mirror.
A two-way mirror is a piece of glass coated with a substance called micro pane. If you stand on the treated side, you see your reflection but the untreated side looks like a tinted window.
If you see a wall behind the mirror, it’s a good bet that it’s nothing more than a regular mirror.
Consider where you are. If you’re in a public place and in an area you’d expect privacy, such as a restroom, it’s unlikely and illegal to have a two-way mirror. On the other hand, two-way mirrors are frequently used by law enforcement. For example, two-way mirrors are used in interrogation rooms and for lineups.
The use of two-way mirrors is closely tied to issues of personal privacy and Constitutional rights. Most states have passed additional legislation preventing the use of two-way mirrors in rest rooms, locker rooms, showers, fitting rooms and hotel rooms.If a location has chosen to use two-way mirrors or surveillance, they are required to post signs that notify you.
Many places, such as gas stations, will use one way metal mirrors because glass mirrors can be destroyed by users. If the mirror in question is metal, then it is not a two-way mirror.
Part 2 of 2: Examining the Mirror
Try to peer through the glass. Press your face up to the mirror and cup your hands around it, creating a dark tunnel to block out as much light as possible. When you do this, if the light in the observation room is at all brighter than the light on your side of the mirror, you should be able to see something beyond the glass
Shine a light on it. If you’re still not convinced, turn off the lights, then hold a flashlight to the mirror (it can even be the “flashlight” on your smartphone). If it is a two-way mirror, the room on the other side will be illuminated and you’ll be able to see it.
Sound it out. Tap on the surface of the mirror with your knuckle. A normal mirror will produce a dull, flat sound, since it’s placed in front of a wall. An observation mirror will produce an open, hollow and reverberating sound because there is an open space on the other side.
Consider the extreme measure of breaking the glass. If it’s a regular mirror, it will shatter and you’ll see the mirror’s backing or a solid wall. If it’s a two-way mirror, you’ll see the room behind the mirror. You should probably only consider this option if you feel threatened or are in danger. Breaking the glass will cause damage and create a safety hazard.