When we visit hotel rooms, changing rooms, toilets, etc. how many of you know for sure that the seemingly ordinary mirror hanging on the wall is a real mirror, or actually a 2-way mirror(that they can see you, but you can't see them).
Many cases of people installing 2-way mirrors in female changing rooms or bathroom or bedrooms. May be someone is making a film on you.
It is very difficult to positively identify the surface by just looking at the mirror.
So, how do we determine what kind of mirror we are looking at?
How to know if it is two way or not?
A two-way mirror is glass which, on one side, provides a reflection, but on the other side, functions as a window. It is used to observe people so that they are not aware that they are being watched, or who is watching them. Two-way mirrors (also known as one-way, transparent, and observation mirrors) are not uncommon in police stations or psychological institutions, but there are other, less obvious settings where people worry about being watched, such as dressing rooms and workplaces.
1. Observe how the mirror is installed. A normal mirror is hung against the wall, but an observation mirror is set into the wall. If the wall is behind the mirror, it's probably a normal mirror.
2. Turn off the lights and hold a flashlight or even a small personal flashlight to the mirror. If it is a two-way mirror, the room on the other side will be illuminated.
3. Press your eyes against the mirror and cup them with your hands, creating a dark "tunnel" to block out the light. When you do so, the light in the observation room will be brighter than the light on your side of the mirror, and you should be able to see something beyond the glass.
4. Tap on the surface of the mirror with your knuckle. A normal mirror will produce a dull sound because it is placed in front of a wall. A two-way mirror, however, will produce an open, hollow, and reverberating sound, because there is an open space on the other side.
Or you can conduct this simple test:
Place the tip of your fingernail against the reflective surface and if
there is a GAP between your fingernail and the image of the nail,
then it is a GENUINE mirror.
However, if your fingernail DIRECTLY TOUCHES the image of your nail, then BEWARE, MAYBE IT IS A 2-WAY MIRROR(a first-surface mirror)!
But, "this fingernail test" is not as reliable as any of the methods above. These two ways mirror(first-surface) are quite expensive and would not be installed under ordinary circumstances. All observation mirrors are first surface mirrors, but not all first surface mirrors are observation mirrors.
Some places, such as gas stations will use one way metal mirrors because glass mirrors can be destroyed by users.Make sure and check every time you enter in hotel rooms. No test for a two-way mirror is foolproof. There only needs to be a very small opening in the wall for a hidden camera with a fisheye lens, and there won't be any giveaway illumination on the other side, or any hollow sound, or anything to see with your cupped hands. Even if themirror is a normal one, there are many other places to hide observation devices.