Crown glass


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crown glass

[′krau̇n ‚glas]
(materials)
A soda-lime glass, typically having 72% SiO2, 13% CaO, and 15% Na2O, which is hard and will take a simple polish; highly transparent for visible light.

Crown glass

1. An early form of window glass, cut from blown disks.
2. The glass made by blowing a mass of molten material, which is then flattened into a disk and spun into a cular sheet.
See also: Glass

crown glass

A handmade glass of soda-lime composition, used for windows; manufactured in the early 19th century by a now-obsolete process in which a hollow sphere of glass was blown while still very soft, then spun to form a large, nearly flat circular disk. During the spinning process, ripple lines were formed in a pattern of concentric circles, with their center at the center of the spun disk; this central area was used in a bull’s eye window. Also see glass.
References in periodicals archive ?
Some small loss from CR39 and Crown glass does not cause too many problems.
Richter's design called for BK-7 optical glass, but since this is difficult to obtain in Argentina I opted for ophthalmic crown glass instead.
For most designs, prisms made of Bak4 (barium light crown glass) are preferred over the industry-standard Bk7 (borosilicate crown).
Seeing the Northern Lights is high on most people's wish–lists and this dream came true for me in the coolest of locations – the Golden Crown Glass Igloos in Levi, Lapland (inghams.co.uk).
Since the prism and lens are both made of very similar crown glass, experienced amateurs could even grind and polish the crown's curved surface directly onto the prism, avoiding the need to make a separate lens.
But it's best to see them away from any light pollution, such as at the fabulous Golden Crown glass igloos near Levi, or mountain restaurants like Tsokka above Pyha, where we were taken to.
Thus crown glass reflects 4.2 percent, flint 5.6 percent, and Pyrex 3.6 percent.