Glass, opal

Since weathering is deterrnined primarily by clouding which changes transmission, a rating for the opal glasses is omitted. At 10 kHz. 

Triibglas, n. translucent glass (frosted glass, opal glass, etc.). 

Amino (melamine and urea) Melamine formaldehyde (MF) have excellent electrical properties, heat and moisture resistance, abrasion resistance (good for dinnerware and buttons) in high-pressure laminates it is resistant to alkalies and detergents. They are used as the plastic for counter tops. Urea (urea formaldehyde) has properties similar to melamine and is used for wall switch plates, light-colored appliance hardware, buttons, toilet seats, and cosmetics containers. Unlike MFs they are translucent, giving them a brightness and depth of color somewhat similar to opal glass. 

The powders used in dental silicate cement are unusual in being ground opal glasses rather than crushed crystalline clinker. The glassy nature of the powder gives the set cement the unusual property of translucency... 

The easiest way to calibrate a light scattering photometer is to use a suitable standard as a reference. Although polymer solutions and dispersions of colloidal silica have been used for this purpose, commercial photometers are equipped with opal glass reference standards. 

Comparator Use either the standard Hellige comparator (Orbeco, Catalog No. 607) or the pocket comparator with prism attachment (Orbeco, Catalog No. 605AHT). The comparator should be illuminated with a 100-W frosted lamp placed 6 in. from the rear opal glass of the comparator and mounted so that direct rays from the lamp do not shine into the operator s eyes. 

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