Milk glass

Milk glass is the colloquial name for opaque white glass, a type of glass is translucent but opaque. Thus, the glass acts white and cloudy and is therefore also called turbidity glass.

There are basically different ways to achieve this effect: By adding a clouding substance or by subsequent roughening of the surface.

Turbidity due to admixture

By the addition of calcium phosphate, fluorides or tin oxide, prior to melting a haze of the glass is achieved. This is often bone ash has been used, leading to the term Beinglas derived to describe this type of glass. Milk glass by addition of cryolite - a fluoride - arises, is also called Kryolithglas.

Turbidity caused by roughening and / or coating

The glass surface is roughened by either acid etching or sandblasting. The result is a surface like a matte screen. Due to the roughened surface, the light can no longer freely through the glass, so that turbidity appears to the eye. This effect is comparable to that of a still water surface in pure water to look at the reason permits and troubled water the ground can not be identified. Alternatively, this can also be achieved through the coating by means of a special film (see glass decoration film ). The attachment of a glass decoration film is not a structural measure dar. Since the film at any time easily can be removed, clear glass is by applying an opaque film not to frosted glass.

Applications, alternatives

Turbidity due usually mostly one-sided roughening effect is not as strong scattering as strong milky turbidity in the substance. The effect of the roughness of the surface can be significantly reduced by wetting with water or oil, the valleys (n = about 1.5 refractive index) glass in this case with water ( n = 1.33 ) optically to air ( n = 1) to 2/3 ironed out. In the lighting for photography and film are also superficially structured or used in itself opaque plastic, vellum or translucent tissue that are unbreakable, lightweight and collapsible as cloudy areas.

In the light sources of the simple tungsten filament lamp a certain turbidity is achieved by Innenmattierung of the piston, a stronger, however. By a comprehensive internal coating of scattering powder Fluorescent tubes are matted by adhering inside bulbs powder at the same time, tubes screens by printed phosphors.

The filled red or blue colored alcohol capillary of a liquid thermometer is for high-contrast visibility often made ​​of frosted glass. Lights, which should appear very evenly bright, be in opaque milk glass, often performed in a spherical shape, but this also absorbs a certain amount of light. Rather, only small flat surfaces, are about in railway turnouts signal cubes or exported in milk glass in metal frame, larger areas today. Often in opaque acrylic glass that is lighter, and more impact resistant