Plate glass is the usual material for making domestic mirrors. One side of the glass is coated with a reflective surface, usually metallic. The highly polished surface makes for an an ideal, and if need be, invisible, way of filling a room with light and a sense of space.
Silvered mirrors have a thin layer of silver as a coating on one side of the glass. Early metal-plated mirrors used various metals including tin and mercury, but silver has emerged as a cost-effective metal with the highest reflective index. It reflects all wavelengths of light, and gives the brightest, highest quality reflective surface. This lends itself to decorative interior mirrors, and functional items such as bathroom mirrors.
Details such as beveled edges can add decorative effects to an interior mirror, and bring further reflections of light and color from around the room, and light sources such as windows and lamps. They can also create attractive effects such as framing a focal point in the room, or making a face appear as part of a portrait.
A plane mirror is the term for a flat, or planar, reflective surface. It creates a reflection of similar size and shape to the original object. Ancient Turks and Romans used polished metals such as copper and bronze. The modern thin layer of plate glass emerged to protect the surface from tarnishing and other damage.
Spherical / Curved Mirrors
Spherical and curved mirrors have specialized uses, in scientific equipment and also in everyday objects. A shaving mirror is an example of a concave mirror. Its surface curves inwards, like the inside of a spoon, and reflects light inward towards a focal point in front of the mirror. This has the effect of magnifying the reflection in the centre of the mirror.
A convex mirror curves gently outward, and produces a slightly reduced reflection, that is distorted at a wider angle near the edges. These mirrors have many safety applications for seeing around blind corners, and blind-spot and parking mirrors on cars and trucks.
One Way Mirrors
One-way mirrors are only partially reflective. They may not provide the brightest image, but a thin reflective layer makes it possible to see into a lighted room, from a darkened space behind the mirror. From the lighted room, the mirror appears opaque.
These have many uses, including squash courts, security observation decks and interrogation rooms. Surveillance equipment such as security cameras can be concealed behind a small mirrored housing or panel.
These are some of the most common types and uses of mirrors. Established and inexpensive uses of domestic mirrors will endure for some time. Technological advances and hunger for innovation means mirrors will continue to develop and evolve.
New materials and manufacturing bring possibilities for replacing or augmenting them with video screens, mirrors in more complex and pliable forms, or ones that do away with glass.