How to check if a mirror is a two way or not
Have you ever been in a hotel room, 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.
5 steps to expose the two way mirror
1. 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.
2. 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.
3. 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.
|A two way mirror.|
|A one way mirror.|
4. Perform the fingernail test. While not completely accurate, you can use your fingernail to determine if the mirror is a first or second surface mirror. Simply place your fingernail against the surface of the mirror. When you touch your fingernail to a second surface mirror, you can't to touch your own reflection; instead, you will see a gap caused by a second layer of glass over the mirrored surface. When you touch your finger to a first surface mirror, you can touch your own reflection, since there's no additional layer of glass in between. First surface mirrors are very rare, so if you find one there's likely to be a very specific reason and it's very possible that it's a two-way mirror. Second surface mirrors are your ubiquitous everyday mirrors.
- Due to variables like lighting and the material with which the mirror is manufactured, it can be really difficult to tell whether you are truly touching your reflection or not. You might think you're touching a first surface mirror when you're actually not.
- Also, it's possible for a two-way mirror to be a second surface mirror. If other aspects of the situation, like the mirror's setting and lighting, have indicated that what you're seeing is a two-way, don't let the fingernail test be the deciding factor.
5. 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.