Silver screen

A silver screen, also known as a silver lenticular screen, is a type of projection screen that was popular in the early years of the motion picture industry and passed into popular usage as a metonym for the cinema industry. The term silver screen comes from the actual silver (or similarly reflective aluminium) content embedded in the material that made up the screen's highly reflective surface.

Actual metallic screens are coming back into use in projecting 3-D films.

Silver lenticular (vertically ridged) screens, which are made from a tightly woven fabric, either natural, such as silk, or a synthetic fiber, were excellent for use with low-power projector lamp heads and the monochromatic images that were a staple of early projected images. Other silver screens are made by taking normal matte sheets and adhering silver dust to them; the effect is the same.

True silver screens, however, provide narrower horizontal/vertical viewing angles compared to their more modern counterparts because of their inability to completely disperse light. In addition, a single projection source tends to over-saturate the center of the screen and leave the peripheries darker, depending on the position of the viewer and how well adjusted the lamp head is, a phenomenon known as hot-spotting. Due to these limitations and the continued innovation of screen materials, the use of silver screens in the general motion picture exhibition industry has mostly been phased out.

Silver lenticular screens, while no longer employed as the standard for motion picture projection, have come back into use as they are ideally suited for modern polarized 3-D projection. The percentage of light reflected from a non-metallic (dielectric) surface varies strongly with the direction of polarisation and the angle of incidence; this is not the case for an electric conductor such as a metal (as an illustration of this, sunlight reflected from a horizontal surface such as a reflective road surface or water is attenuated by polarized sunglasses relative to direct light; this is not the case if the light is reflected from a metallic surface). As many 3-D technologies in use today depend upon maintaining the polarisation of the images to be presented to each eye, the reflecting surface needs to be metallic rather than dielectric.

...
Wikipedia