How to prevent voyeurism by double-sided mirror？

In recent years, incidents of peeping through double-sided mirrors have continuously occurred, which has become the focus of attention in the society. There are many ways to prevent double-sided mirror peeping on the Internet, such as finger identification, light identification and so on. However, these methods can’t accurately identify whether the mirror is a double-sided mirror or a single side mirror.

 Finger identification: It’s the most commonly used method of identification.

It’s said that touch the mirror with your fingertip, if there is a gap between the finger and the mirror, that’s a single side mirror. If there is no gap between the fingertip and the mirror, that’s a double-sided mirror.

However, this method is not work. How to identify a single side mirror or a double side mirror? Let’s figure out how it work.

No matter it’s single side mirror or double side mirror, it’s made of acrylic sheet + electroplate a layer of metal. But single side mirror is covered by an opaque film, it’ll reflect the light completely. Double side mirror is covered by an semi-transparent film, it’ll transmit a part of light and reflect the rest. This kind of mirror, it’s called Two Way Mirror.

The combination of Two Way Mirror: acrylic sheet + semi-transparent layer of metal + OPAT/BOPP film

So, light transmittance of the Two Way Mirror are the same no matter the front side or back side.

Finger identification: Single side mirror will have a gap when we put our fingers on it. However, two way mirror will have a gap on the mirror side, the other side (the electroplate side) don’t have a gap.

Conclusion: when there is a gap between our fingertip and the mirror, that could be a single side mirror or double side mirror (two way mirror). So finger identification is not work.

How to prevent voyeurism by Double Side Mirror or Two Way Mirror?

Method 1: Tap the mirror and listen to the sound

If the sound is hollow and echoed, it might have a room covered by the mirror, and there is a high possibility the mirror is a double side mirror. Because the single side mirror need to be attached to a flat wall.

Method 2: Turn off the light, turn on the flash and get close to the mirror to check it has light transmitted or not.

From above introduction, we already know that two way mirror can transmit a part of light and reflect the rest. Turn on the flash in the dark room, it’ll transmit a part of light to the opposite room, we can see the room if we get close to the mirror.

Method 3: Contrast brightness with a make up mirror

If a two way mirror at 20 transparency, it will reflect 80% light and the rest will transmit through the mirror. However, the light transmittance of ordinary mirror is 95%. If we turn on the light, the image of ordinary mirror will more clear than two way mirror. Because two way mirror’s light transmittance is lower than 95%.

Identify the mirror by above methods, you’ll clearly know that it’s a single side mirror or a double side mirror. Take care.