Traditional dance studio mirrors are made of high-quality glass that covers at least one wall, and usually two or three walls of the studio space, most or all of the way from ceiling to floor. Alternatives made from synthetics, polyester film, or acrylics are called "glassless glass" and offer lower cost, lighter weight and shatterproof advantages that may appeal to those with modest budgets or home studios. Portable mirrors are another choice for multipurpose practice studios and personal dance spaces.
The mirrored walls of a dance studio reflect technique, ensemble symmetry and the choreography for those in the back of the group. Traditionally, dance studios covered all or most of the walls in thick commercial glass mirrors with polished edges that fit seamlessly together. The panels of the mirrors slide into J molds that have channels to hold the glass, so it doesn't need drill holes and can be moved. A safety backing holds the glass on the wall in case of breakage. The heavy glass is free from distortion, to permit accurate evaluations and self-correction.
Acrylic glass and other synthetics are much lighter and more flexible, so the larger sheets are prone to distortion. Glassless glass does represent a significant savings for a studio and is light enough not to damage walls. Polyester film and other highly reflective glassless surfaces are shatterproof and easily framed and mounted on wheels as large portable mirrors. That makes the technology a good choice for shared spaces, such as a school gym that doubles as a dance and rehearsal studio.
Lighter gauges of real glass or sheets of glassless glass are used in home dance studios, either in portable frames or mounted directly on the wall. The lighter weight makes them easier to install and remove, with minimal damage to the walls.