●What is Two-way mirror?

Put very simply, Two-way mirror is either a clear glass, specially coated on one side or containing a coated laminate. The coating allows light to pass through the clear sheet in a restricted fashion, i.e. limiting the amount of light from one side more than the other. When less light comes through, the glass as a mirrored surface, conversely as more light comes through, the glass appears as a clear sheet of glass, although normally with a slight tint.

Two-way mirrors are a very improbable type of mirror. Often known by other names, such as a one-way mirror, one-way glass, spy mirror, magic mirror, mirrorpane or smart mirror. Whichever name you know them by, one thing is for certain, they are incredible. With 100’s of varying uses, their abilities are only limited by one's imagination. For use in domestic and commercial projects, we know we have the right two-way mirror for you.

Let's see the video about two way mirror.

https://youtu.be/ljInuKgnk2A

How to know if a Mirror Is Two Way or Not?

Perform the fingernail test. While it is not completely accurate, you can use your fingernail to determine if the mirror is a first or a second surface mirror. Simply place your fingernail on the surface of the mirror. When you touch your fingernail to a second surface mirror, you can't 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.