Types of Mirror
     There are many types of mirror, each with varying purpose and design.  Here is a general list of the types of mirror, as well as their function.

SILVERED MIRRORS
Virtually all mirrors for interior use are manufactured by the conveyor, wet deposition method. Annealed or fully tempered glass is thoroughly cleaned by the application of cleaners and passing contact with oscillating scrub brush units. After the glass is cleaned and rinsed, the surface of the glass is sensitized with a diluted solution of tin chloride. This surface treatment allows for the deposition of silver. Silver nitrate is sprayed onto the sensitized surface of the glass along with other chemical configurations. The final outcome is the formation of a uniform silver layer on the glass.

Once the silver layer is formed on the glass, methods to protect the silver layer from oxidation are employed. A layer of copper is then deposited directly onto the silver. Copper can be applied in two ways: chemically or galvanically. Recent technological advances have lead to the development of copper free protective films, which also prevent silver oxidation.

Once the metal layers are attached to the glass, they are covered by a protective mirror backing paint. The mirror backing paint protects the metal layers from corrosion and from mechanical scratching. The paint can be applied either by passing the glass through a curtain of paint or by passing glass in contact with a roller paint coater. There are many mirror backing paint products available from a number of suppliers. They offer paint systems that are applied as a single coat or double coat. Both coating systems are effective.

Clear Mirror: Clear glass with a silver backing, copper and paint. This is the standard mirror used in the majority of applications. Thicknesses are 3/32, 1/8, 3/16 and 1/4 inch. The largest standard size is 65” x 84” with other sizes available if custom ordered.

Ultra Clear Mirror: Made with glass with a reduced iron content. The glass itself does not have the very slight greenish tinge in found in clear mirror, making it appropriate for fur salons and all white interiors where absolute clarity is a must.

Antiqued Mirror: Coatings or tints are applied to make the mirror look as if it has deteriorated with age.

Concave Mirror: Glass is curved inward, and then coated, creating enlarged reflections. Useful as a grooming aide.

Convex Mirror: The glass curves outward, creating reduced reflections. It can be either decorative or a useful tool in parking garages or busy corridors to help people see around the corner.

First-Surface Mirror: Whereas standard mirror has the reflective coating on the back of the glass, this coating is on the front. Highly fragile, it is optical mirror for cameras and kaleidoscopes. Occasionally it is used by designers and artists.

SILVERED TINTED MIRRORS
Tinted mirrors are produced using the methods described above. The silver coating is applied to one of the various tinted glass substrates available on the market. Tinted mirrors are generally used in decorative applications where color and diminished light reflection are desirable.

SILVERED SAFETY MIRRORS
Tempered Mirrors: These are manufactured using fully tempered glass as the substrate. There are optical characteristics inherent in tempered mirrors, including roll distortion and the lack of a quality surface for silvering.

Laminated Mirrors: These are manufactured by combining clear glass, either annealed, heat-strengthened or fully tempered, and mirrored glass.

Safety Backed Mirrors: These are known as Organically Coated Mirrors in the CPSC 16 CFR 1201 and ANSI Z97.1 standards. These are manufactured by applying a sheet of adhesive backed polyethylene material to the back of annealed mirrors. The backing material does not prevent breakage of mirrors, but lessons the potential of injury on impact by retaining the fragments.

NON-SILVERED MIRRORS
There are two types of non-silvered mirrors: pyrolytic mirrors and transparent/two-way mirrors.

Pyrolytic Mirrors: These are highly reflective coated glass products with performance characteristics approaching that of silvered mirrors. This product is promoted for use in shower doors and other areas where moisture can affect the substrate of silvered mirrors.

Transparent/Two-way Mirrors: These are composed of reflective glass products, and as such are not silver mirrors. Transparent mirrors are manufactured by both the pyrolytic deposition and vacuum deposition coating processes. Heavy density coatings are offered on clear and gray tinted glass.

Transparent or two-way mirrors are designed to permit vision through one direction while giving the appearance of a standard mirror from the opposite side. Their major application is to permit undetected observation for study or surveillance in interior conditions such as learning centers in schools and universities, medical and psychiatric clinics, and security stations in casinos or high-traffic retail stores.

The transparent mirrors work by reducing the visible light transmittance through the glass. To ensure proper performance the room lighting design and surrounding conditions must be carefully planned and executed. The glass surface in the subject room must appear to be standard mirror. In order to achieve this condition, the coated surface should be toward the subject room and the lighting ratios tightly controlled. For applications utilizing clear glass, manufacturers recommend a lighting ratio of 10:1 subject’s side to observer’s side. If the lighting ratio drops to approximately 5:1, the subject may detect movement or silhouettes through the mirror. If 10:1 lighting ratios can not be maintained, a gray transparent mirror should be specified. Lighting ratios of 5:1 can be successfully used for gray transparent mirror products.

Design considerations call for bright contrasting colors in the subject room and dark, non-contrasting colors in the observer room. Light color surfaces or objects may be noticeable to the subject. The design of the observation room should also prevent sudden light ratio changes. Special care must be taken if transparent mirrors are used on more than one wall.

Metal Mirror: Highly polished sheets of metal used in areas that require utmost safety and security.

Plastic Mirror: Plastic sheets are coated with metal to make them reflective. While they have less optical clarity, are softer and easier to scratch than glass mirrors, they have usefulness in crafts, displays, children’s furniture and toys.

© GANA Mirror Division