How to Detect a 2-way Mirror

Don't believe any emailed rumors you may have received about secret two-way mirrors placed in dressing rooms and restrooms. Find out for yourself whether these secret mirrors exist. If you are close to it, a two-way mirror is actually easy to detect through sight alone.

Difficulty: Moderately Easy

Instructions

1. Realize that a popular email about two-way mirrors you may have received is a hoax. It is simply an urban legend that has gained credibility as it has gone from one recipient to the next. You can check suspect stories you hear against the urban legends database at Snopes.com.

2. Understand that a two-way mirror is specially treated glass that allows light to pass through in both directions, but which also reflects light back into the room. If lights are off on one side of the mirror and on in the other, those on the bright side will see a reflection and those on the dark side will see through the glass.

3. Know that because they function as windows, two-way mirrors are generally set into the wall; they are not hung on a wall. If the mirror is not flush with the wall, it is most likely not a two-way mirror.

4. Test the mirror. Cup your hands around your eyes and place your face next to the mirror. If it is a two-way mirror, you will be able to see something on the other side—unless there is absolutely no light on that side.

5. Turn out the lights. The two-way mirror only works if light is more intense on one side. With the lights off, you will see through a two-way mirror. It may take a few moments to detect the mirror as your eyes adjust.

6. Tap the mirror. A two-way mirror will produce a hollow sound like a window because there is no backing on the other side. A regular mirror will sound dull.

Tips & Warnings

• The "fingernail test," recommended by hoax emails and passed around online, does not work. In fact, it simply reveals where the reflective surface is on the mirror; some mirrors have the reflective surface placed on the surface, and some have glass laid over it.
• Be ready to get strange looks if you try to detect a two-way mirror in public!
• Though breaking a mirror will show you exactly what you have been looking at, it is not recommended.

Resources

• Check out stories at Snopes.com to see if they are urban legends.

[lilaclady]

on 2/18/2008 Oh I always believed the fingernail test, thanks for the enlightenment...