Opaque glasses

Then swirl well and pour the brew into a coffee filter in a glass, opaque plastic or metal funnel. When the dripping stops, take out the fitter and gently squeeze out the remainder ci the acetone. Sp d the fitter on a newspaper and let it cb. ... 

Optical Lithography. Optical Hthography uses visible or ultraviolet light as the exposure media, and is the dominant Hthographic process used for patterning IC wafers. The linewidth limit is near 0.4 p.m, although some narrower features may be possible (34). The masks typically are made from patterned, opaque chromium films on glass. 

The Cannon-Fenske viscometer (Fig. 24b) is excellent for general use. A long capillary and small upper reservoir result in a small kinetic energy correction the large diameter of the lower reservoir minimises head errors. Because the upper and lower bulbs He on the same vertical axis, variations in the head are minimal even if the viscometer is used in positions that are not perfecdy vertical. A reverse-flow Cannon-Fen ske viscometer is used for opaque hquids. In this type of viscometer the Hquid flows upward past the timing marks, rather than downward as in the normal direct-flow instmment. Thus the position of the meniscus is not obscured by the film of Hquid on the glass wall. 

Density. The density of transparent vitreous sihca is approximately 2.20 g/cm. Translucent and opaque glasses have lower densities owing to the entrapped bubbles. The density of translucent Vitreosil, for example, is 2.07—2.15 g/cm (87,119). The density of transparent vitreous sihca decreases with increasing hydroxyl content and with lower fictive (glass stmcture equihbrium) temperatures. The fictive temperature depends on the thermal history and on glass viscosity (120). 

Many silver compounds are unstable to light, and are thus shipped ia brown glass or opaque plastic bottles. Silver compounds that are oxidants, eg, silver nitrate and iodate, must be so identified according to U.S. Department of Transportation (DOT) regulations. Compounds such as silver cyanide, which is toxic owiag to its cyanide content, must carry a poison label. However, most silver compounds are essentially nontoxic. 

Most electroless silver appHcations are for silvering glass or metallizing record masters. Mirror production is the principal usage for electroless silver. The glass support is cleaned, catalyzed using a two-step catalyst, and coated on one side with an opaque silver film (46). Silver-plated nylon cloth is used as a bacteriostatic wound dressing. A tiny current appHed to the cloth causes slow silver dissolution. The silver acts as a bactericide (47). 

Titanium Dioxide. The recrystallization of titanium dioxide in a cover-coat glass is very important to the development of thin, highly opaque finish coats. Titania, Ti02, is the primary opacifying agent for white finish coats. Two polymorphic forms of titania, anatase and mtile, may be present in... 

As the level of opacifier is lowered in a glass system, the level of opacification drops. This yields semi-opaque glasses which allow the development of soft pastel colors. Strong colors result from clear glasses. The clarity allows the use of ceramic pigments (qv) (mixed-metal oxides) for the development of a wide variety of colors in almost any hue, saturation, and brightness. 

FIG. 19-12 Optical separation of mixed glasses separation of opaques from glasses. Coutiesy Gunson s Sotiex Ltd.)... 

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