AN IMPROVED METHOD OF HARDENING OR TOUGHENING GLASS, AND APPARATUS THEREFOR
Year: 1877

page_text: LETTERS PATENT to Theodor Bock, of Mincing Lane, in the City of London,
Merchant, for the Invention of "AN IMPROVED METHOD OF HARDENING OR
TOUGHENING GLASS, AND APPARATUS THEREFOR." A communication from
abroad by A. Neeser, senior, of Augsburg, in the Kingdom of Bavaria.
PROVISIONAL SPECIFICATION left by the said Theodor Bock at the Office
of the Commissioners of Patents on the 14th August 1877.
"
AN
THEODOR BOCK, of Mincing Lane, in the City of London, Merchant.
IMPROVED METHOD OF HARDENING OR TOUGHENING GLASS, AND APPARATUS
THEREFOR." [A communication from abroad by A. Neeser, senior, of Augsburg, in
the Kingdom of Bavaria.]
This Invention relates to an improved method of toughening or hardening glass,
whereby the use of annealing furnaces or ovens, as in the ordinary process of
annealing, or of oil baths, as in the manufacture of the so-called toughened glass, is
entirely dispensed with, and the following advantages secured :-
(1.). Articles of any form and of unequal thickness may be toughened or hardened,
whereas, by the toughening processes heretofore known, only articles of tolerably
uniform thickness could be toughened, articles having thick bottoms, feet, or
handles being excluded.
(2.) The cost of toughening or hardening glass is greatly reduced, the only
apparatus used being of a very simple character, instead of the expensive and
inflammable baths heretofore used.
(3.) The cleaning and other operations necessary when oil baths are used are not
required, every article, when cooled, being clean and ready for packing.
(4.) The skill and care necessary to maintain the same degree of heat, and subject
each article according to its construction for a proper time to the action of the bath,
are not necessary, as this improved method of toughening is absolutely certain and
uniform in its result, and all liability of accident is avoided.

page_text: According to this Invention the article of glass, when removed from the glass-
blower's pipe, is placed in a heated metal stand on a horizontal smooth metal plate,
and is then covered with a metal shell cover or casing, so as to entirely exclude the
external air from all contact with the glass.
The shell is shaped to correspond to the form of the article, and lined with a
non-conducting material or with wire netting, in order that the glass shall not touch
the heated metal shell or the stand, but shall be surrounded by an intervening air
space, which serves to protect it whilst cooling.
For articles of uniform thickness the stand may be made of thin plates; but for
thick-bottomed articles, bottles and glasses, and other articles having feet or
pedestals, the stand must be provided with a rim, according to the nature of the
glass bottom and the thickness of the side. In the case of jugs and glasses with
handles the stand must also be furnished with an appendage which encircles the
glass handle.
Non-conducting materials may be used for the stands, covers, and plates, but
metal is preferable, as the quicker the glass is-cooled whilst protected from the
external air the better, and therefore covers made of a good conducting material
and as thin as possible are to be preferred.
The size and thickness of the stands, and the diameter and height of the covers,
are not of much importance, except that the stands must be of such size and
diameter that the articles can be easily introduced, and the rim must be high
enough to enclose so much of the glass as may be of unequal thickness, whilst the
covers must be at least of such height and diameter that they do not touch the
articles enclosed within them.
The thicker portions of the glass, such as pedestals and handles, should not cool
too quickly; and to prevent this the stands beneath them may be made red hot.
For articles of uniform thickness the stands only require to be slightly warmed.
The table on which the stands are placed may be cold, and it is preferable that
the covers which exclude the air should be used cold.
In the case of decanters or bottles, with large rims at the mouth, a cap is applied
to the mouth of the bottle so as to enclose the rim, the said cap being provided
with an aperture for the escape of the heated air from the interior of the bottle,
and made red hot before it is applied.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed bý
the said Theodor Bock in the Great Seal Patent Office on the 14th February
1878.
THEODOR BOCK, of Mincing Lane, in the City of London, Merchant.
" AN
IMPROVED METHOD OF HARDENING OR TOUGHENING GLASS, AND APPARATUS
THEREFOR." A communication from abroad by A. Neeser, senior, of Augsburg, in
the Kingdom of Bavaria.
This Invention relates to an improved method of toughening or hardening glass
ware.
It is well known that glass ware which has been annealed in the ordinary way is
still very brittle and liable to be broken by a blow or a sudden transition of
temperature. This defect is mainly due to the unequal cooling of the glass by the
currents of air which circulate directly in contact with the glass in the annealing
oven or arch.
It has also been found by experience that the annealing operation, as usually
performed, is much too slow, and that the more regularly and quickly the glass is
cooled, whilst protected from the external air, the stronger and the better able to
resist blows or sudden changes of temperature it will be.
I am aware that a method of toughening glass by immersing it in a bath of
heated oil has been devised, but this method, besides being costly and troublesome,
is not uniformly successful with all kinds of goods.
By this Invention the following important advantages are secured :-
1st. The use of the ordinary annealing furnaces or ovens is entirely dispensed
with, and the greater part of the time required for the annealing operation, as
usually performed, is saved.
2nd. The oil bath hitherto employed in the manufacture of toughened glass is
not required, and articles of any form and of equal or unequal thickness may be
uniformly toughened or hardened, whereas by the toughening processes heretofore
known only articles of tolerably uniform thickness could be properly toughened,
those having thick bottoms, feet, or handles being excluded or only partially or
imperfectly toughened.
3rd. The cost of toughening or hardening glass is greatly reduced by the
avoidance of breakages, which are a serious item in the existing methods, and by
the use of apparatus of a very simple character instead of the expensive and
inflammable baths heretofore used:
4th. The cleaning and other operations necessary when oil baths have been used
are not required, every article, when cooled, being clean and ready for packing.
5th. The skill and care necessary to maintain a uniform degree of heat, and
subject each article, according to its construction, for a proper time to the action of
the bath, are not necessary, as this improved method of toughening is absolutely
certain and uniform in its result, and all liability of accident is avoided.
According to this Invention the article immediately after being made is placed
upon or in a separate stand, which has been raised to a cherry-red heat (more or
less), and enclosed in a cover or shell to protect it from the external air.
The stand and cover are preferably of metal, and correspond somewhat in shape
to and are rather larger than the article, so as to surround it tolerably closely,
without however coming into contact with the glass.
For articles of equal thickness on all sides a flat plate of metal suffices for a
stand; but for thick-bottomed articles and glasses, jugs, or other articles with feet,
pedestals, or handles, the stand must be cup-shaped, or be provided with upwardly
rising sides enclosing the article and its handle (if any) to a sufficient height to
prevent a too rapid cooling, and the thick rim at the neck and mouth of a decanter
are preferably enclosed by a metal cap, also warmed, and provided with an aperture
in the end for the escape of the heated air from the interior.

page_text: The thickness of the stand may vary, according to that of the glass, but I find
the thickness shown in the Drawings answers well in most cases.
The cover or shell which encloses the article, and also the stand in or on which it
is placed, should be of sheet iron or other metal, and as thin as possible.
The stands may be fixed on an iron plate forming a table; it is unnecessary to
warm this plate or the sheet-iron cover or shell.
If the article is uncovered and removed from the stand, whilst still hot, it should
be transferred as quickly as possible to a covered wooden case to protect it from
cold currents of air; but it is in all cases preferable to keep it enclosed until it can
be removed with the bare hand.
Figures 1, 2, 3, and 4 represent vertical sections of stands and covers, as used
respectively for hardening or toughening a tumbler, wine glass, decanter, and
glass mug.
'
Figure 5 is a horizontal section of Figure 4 to show the shape of the stand and
cover in the case of a jug or vessel provided with a handle.
A is the stand made of the best cast iron. In some cases it may be a flat plate;
but for articles such as those represented it has upwardly rising sides a, a, enclosing
the thicker portions of the glass, as shown. B, Figure 3, is a cap enclosing the
mouth and neck of a decanter having a thick rim or neck. C is the box or cover
of sheet iron from, say, 1/2 to 1 millimetre in thickness, open only at bottom, and
stood over and enclosing the article and its stand, as shown, the lower edge of the
cover fitting down close on the table on which the stand A is placed to exclude the
external air.
Having described the nature of the said Invention and the manner of performing
the same, I declare that what I claim as the Invention to be protected by the
herein-before in part recited Letters Patent is, the improved method of toughening
or hardening glass ware, which consists in placing it on or in a heated stand or
other equivalent device, surrounding the thicker portions of the glass (if any), and
enclosing the whole with a thin sheet metal cover or shell, and allowing the glass
to cool whilst so enclosed and protected from external currents of air, substantially
as herein shown and described.
In witness whereof, I, the said Theodor Bock, have hereunto set. my hand
and seal, this Thirteenth day of February, in the year of our Lord One
thousand eight hundred and seventy-eight.
THEODOR BOCK.
(L.S.)