Making a one-way mirror may seem complex. After all, you probably have to do something to one side of a mirror to make it transparent. Either that, or you have to do something to one side of a window to make it look like a mirror. In truth, the process is much simpler. The key to a one-way mirror is in the lighting.

Step 1

Place the thinly silvered mirror between two rooms. The silver on the mirror will reflect a small amount of light, but most of the light will pass through the mirror.

Step 2

Adjust the lighting so that one of the adjoining rooms is very dim and the other is very bright.

Step 3

Look through the mirror while standing in the bright room. In this room, a lot of light is directed at the mirror. Therefore, even the small amount that is reflected is enough to make the surface look like a mirror.

Step 4

Look through the mirror while standing in the dim room. In this room, very little light is directed at the mirror. However, a lot of light from the other room is passing through the mirror into the dim room. Therefore, you will be able to see through the mirror.