Laboratory Glass-Working for Scientists - Sciencemadness Dot Org

SOME TYPES OF GLASS FOR SPECIAL PURPOSES
Fused Silica
The Thermal Syndicate Ltd make fused silica (Vitreosil) tubes of
Several kinds. Translucent and transparent Vitreosil are manufactured;
the former is supplied with 'sand', 'satin' or 'glazed' surface,
and the latter usually has a glazed surface. A glazed surface
Should be used in vacuum work; the transparent tubing is best.
Vitreosil tubing is available with a wide range of sizes and with
leveral wall thicknesses. Rods, bars and capillary tubes are available.
Many items of laboratory equipment are manufactured in Vitreosil.
They are specially valuable when high temperatures and high thermal
endurance are needed. The linear expansion coefficient is 0-54 x 10~* 6 .
Graded Seal Glasses
The General Electric Co. makes a range of sealing glasses. For
joining silica to hard glass, and hard glass to soft glass, the sealing
glasses given below can be used. The coefficients of linear expansion
are also given.
Sealing glass type
WQ.31
WQ.34
HA28
G.S.1
G.S.2
G.S3
G.S.4
G*S*5
G.S.6
Expansion
coefficient
l«0xl0-«
2-1 xlO-*
3-2 x 10 6
5-2 x 10~ 6
5-8 x 10-*
6-6 x 10- 8
7-2 x 10-*
7-8 x 10~ 6
8-4 x 10~ 6
Purpose
for silica
to hard glass
for hard to
soft glass
The G.S.1 can be joined to a hard borosilicate glass using as intermediates
a Kovar-sealing glass, a sandwich glass such as Dial 43,
and a tungsten-sealing glass.
Hie Ease of Working Different Types of Glass
The working of fused silica is described in Chapter 10. Pyrex,
Phoenix and Firmasil require either a gas-oxygen flame or a gas-airoxygen
flame. All the operations we describe for Pyrex can also be
carried out with Phoenix. These two glasses are very easy to work,
and very suitable for research work. They join together well. Monax
can be worked without oxygen, and is a most valuable glass for
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