One way mirror glass can be obtained by installing a high reflective window film. Reflective window film is generally made from two sheets of polyester, which has been through a process that deposits a layer of very small particles of metal, usually, aluminum, silver or bronze. This creates a very thin metalized layer in between the polyester sheets, a clear adhesive and thin polyester backing liner is attached and on the other side a scratch resistant coating.
When this reflective window film is applied to glass it creates one way mirror glass under the correct conditions. The most common reflective window film is a reflective silver window film, the darkest usually referred to as silver 20. This silver film gives a silver mirrored appearance; other colours can be combined such as grey, gold and bronze.
How does reflective film work?
When installed to glazing the window tint will reflect images. If you have one room which is dark and another that is very bright the film will allow you to see into the brighter room but from the other side you will just get a reflection of the room you are in. You will not be able to see into the darker room. This works as the film will reflect images, in the dark room there isn’t much light to reflect back and as so the image it is reflecting is very dull, however in the other room it is very bright and so the images reflected are also very bright and defined, this makes it so that when in the darker room you can see the image of the other room.
Your eyes don’t realize that you are looking at a reflection; it looks as if you are looking straight into the other room. Because of the way the film works it means the window tint has limitations, it is recommended to have at least a 4:1 light ratio to get a true one way mirror glass effect. When installing the reflective window film on external glazing the natural sun light will always be brighter than most artificial light stopping people from seeing into the property but allowing vision out, however at night time when the lights are on inside the effect will be reversed.
There isn’t any way around this unfortunately, if you want to have privacy day and night you will need to alter the lighting conditions to get at least a 4:1 light ratio day and night or have a look at a privacy window film which will stop people seeing in and out.