Improvements in or relating to the Manufacture of Sheet and Plate Glass.
Year: 1898

page_text: Date of Application, 6th July, 1898-Accepted, 24th Sept., 1898
COMPLETE SPECIFICATION.
Improvements in or relating to the Manufacture of Sheet and Plate
Glass.
I, PAUL THEODOR SIEVERT, of 43, Eisenstuckstrasse, Dresden, in the Kingdom
of Saxony, in the Empire of Germany, do hereby declare the nature of this inven-
tion and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement:
The well known process of rolling molten glass into plates or sheets between
metallic surfaces-as a rule between an iron plate and a roller or between a pair
of rollers suffers owing to the cooling of the glass by the metal and to the metallic
surfaces becoming porous from the disadvantage that the glass plates or sheets
thus manufactured have an unfinished or hammered appearance and it is impossible
to produce glass thin enough to be used for windows and other purposes.
According to this invention the above drawback is obviated by using for rolling
or pressing the glass comparatively soft elastic surfaces. It is preferable to use
those that are permeable to water so as to ensure a continuous evaporation of
water. Beside wood there may be used for this purpose various fibrous substances
such as asbestos wood, and paper pulp. Plates or rollers are prepared from or
provided with these substances by securing them to metal frames, which plates
or rollers may be either hollow or provided with passages for the continuous
admission of water whereby they are maintained in a uniformly damp condition
or water may be supplied from the outside on to the surface of the material.
When a hot mass of glass is introduced between surfaces thus formed or pre-
pared there takes place an energetic evaporation of water and the fibrous sub-
stance previously swollen becomes compressed and a dense smooth surface is pro-
duced, the pressure of the steam greatly assisting this action. The surface of
the glass receives a faultless polished appearance and raw or hammered places
such as produced by contact with metal are smoothed out or avoided. In this
way it is possible to produce sheet or plate glass as thin as desired.
This improvement may be used directly for manufacturing glass plates and
sheets and in combination with metallic surfaces, the hot glass being first poured
out on a metallic plate which adjoins a wet fibrous plate or roller. It is true that
the use of soft covers which are bad conductors of heat on iron plates etc. for
receiving finished hot glass surfaces or articles is well known. But the object
was to protect the finished articles from a subsequent contact with metal in order
to preserve the brilliancy of the glass and not to manufacture or finish glass plates
or articles by rolling or pressing the plastic glass between soft damp elastic surfaces
of fibrous substances to which this invention relates and to which it is limited.
In order to decrease the wear of the fibrous plates or rollers they may be
impregnated with zinc oxide or some other well known agent rendering them
incombustible. It is in any case advisable to make the parts separate and easily
interchangeable.
If it is desired to use the fibrous plates or rollers only for smoothing or finishing
glass plates said glass plates are rolled in the usual manner between metallic sur-

page_text: faces then the still hot glass plate or sheet is either removed to an adjoining wet
fibrous plate and rolled with a wet roller also made of fibrous substance until all
raw places have disappeared or the rolled still plastic glass plate is passed between
a pair or pairs of damp rollers of fibrous substances or the glass plates are com-
pressed between damp plates of fibrous material.
L
By this subsequent rolling or pressing of the glass already rolled or pressed
between metallic surfaces it is possible to reduce the thickness of the sheets as the
still hot plastic glass is capable of being rolled or pressed out. This is a very
important feature as it thus becomes possible to produce sheet glass of such small
thickness as was impossible to obtain between metallic surfaces by the processes
hitherto employed.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:-
1. In the manufacture of sheet glass compressing or rolling glass when in a
plastic condition between soft elastic surfaces of wood paper or similar fibrous
material.
2. In the process described the employment of damp soft elastic rolling or
pressing devices substantially as described.
3. In the manufacture of sheet glass rolling or pressing glass plates-previously
subjected to a preliminary rolling or pressing between soft and elastic surfaces
in the manner described either simply for the purposes of smoothing and finishing
said glass plates or for simultaneously reducing their thickness.
4. For carrying out the process described the arrangement of compressing or
roiling devices of wood paper or similar fibrous material as a whole or in separate
interchangeable parts with devices for the supply of water to the surface of the
compressing or rolling devices.
Dated this 30th day of June 1898.