New Process for the Total or Partial Hardening of Glass.
Year: 1899

page_text: Date of Application, 26th Aug., 1899-Accepted, 2nd Dec., 1899.
COMPLETE SPECIFICATION.
New Process for the Total or Partial Hardening of Glass.
I, OLIVER IMRAY, of Birkbeck Bank Chambers, Southampton Buildings, in
the County of London, Chartered Patent Agent, do hereby declare the nature of
this invention (as communicated to me from abroad by La Société des Verreries
de Bruxelles, of Brussels, Belgium) and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement:-
The new process for working glass forming the subject of this invention is
characterized by hardening the glass, in contra distinction to the ordinary anneal-
ing process, and by the various considerable advantages resulting therefrom as
compared with the said ordinary process.
In order to enable the difference of this process from the old process of ordinary
annealing to be clearly understood, it will be well first to state that in the new
hardening process which is particularly applicable to the manufacture of cut glass
ware as well as to that of plain glass ware, the process to which the ware is
subjected, does not take place previously to the cutting process as in the old
process of annealing, but on the contrary it takes place in the course of the various
stages of the cutting, and more strictly speaking after the ware has been roughed
out with the iron wheel, but before the final cutting or the end of the cutting
with first the stone wheel, and then with the wheel of wood or cork.
As is well known, the cutting process comprises in reality three operations:-
the roughing out by means of an iron wheel, the cutting by means of a stone
wheel, and the polishing by means of a wheel of wood or cork. Now in the
ordinary process, the annealing is effected before the first cutting operation, that
is to say, before the roughing out, whereas according to the new process which
forms the subject of the present invention, the hardening is effected only after
the roughing out operation.
The new method of working which obviates all the drawbacks of the ordinary
annealing process, has for its chief object to render the cutting as perfect as
possible by avoiding the drawbacks of cutting after the annealing.
The old process which consists in throwing into the hardening bath, the articles
as they leave the hands of the glass blower, these being then completely finished
by the hands of the workmen after a suitable reheating, produces an imperfect
product which cannot compete with the progress of the glass industry at present.
Further, the breakage and waste are considerable, especially in the roughing out
of the articles because the action of the annealing previous to the roughing out
renders the cutting very difficult and very laborious whilst it is at the same time
costly.
Generally the new process is distinguished from the old process by the fact
that the articles to be hardened, after having been annealed and cut to size by the
cutting apparatus, are first heated gradually, up to a certain degree and then
placed in a suitable furnace or oven until they become soft, on special moulds or
suitable tools covered with an insulating material, such as asbestos or other
similar substance which will prevent the glass from adhering to the moulds by
reason of the heat; and then only are they subjected to the hardening operation.

page_text: In this manner the glass becomes hard throughout its thickness and acquires a
remarkable tenacity.
In the manufacture of cut ware, which forms the essential and chief part to
which my invention is applicable, the hardening operation is delayed until the first
part of the cutting or roughing out has been done, that is to say, the procedure is
as follows:-
The article having been brought to the proper dimensions and having been
first annealed as above set forth, is then roughed out on the iron wheel;
This operation leaves the surfaces roughed out, not polished and having a fine
roughness of surface which is extremely favourable to the action of the hardening
bath into which the articles prepared up to this stage and duly re-heated are
immersed, and upon which articles the bath then acts in such a manner that the
hardening action is propagated or is exerted throughout the entire thickness of
the glass. The hardening bath is of the usual kind, consisting of some grease or
oil.
66
After having thus effected the radical" hardening of the articles, the latter
are removed from the bath and are subjected to the cutting operation proper,
that is to say, to the operation of the stone wheel which then takes place in the
then state of the glass with an absolute precision and correctness, that is to say,
there is produced a remarkable clearness of shape, the facets are well defined,
straight, the edges are correct and with sharp angles, in a word, the cutting
is perfect, deep, and of faultless regularity.
Finally, after this operation, the articles are subjected to the last stage of the
cutting process, that is to say, to the polishing operation of the wheel of wood
or cork, which thus finishes the treatment to which the article is subjected, and
whereby a product is produced which can be compared with that produced with the
finest crystals which have not been hardened.
In the foregoing, mention has only been made of the manufacture of articles
hardened throughout their mass, that is to say, of articles hardened
in their entirety. There are other articles of glass ware, the edges of
which only are to be hardened. These last mentioned articles, without having the
great tenacity of the first mentioned articles, have however valuable advantages,
especially as regards the articles with thin edges, and more particularly those
glases known by the name "Muslins."
In order to enable the following description to be understood I have illustrated
in the accompanying drawing a goblet just detached from the blow pipe or rod of
the glass worker.
According to existing methods the whole article, as shewn in the drawing, after
having been annealed as a preliminary step is first cut to the desired size along
the line abby known mechanical means. As the edge a b is rough, it must be
softened. For this purpose the cut piece is reheated in a furnace, a burner, a
blow pipe, &c., which completes the manufacture by softening the edges. This
mode of operating gives rise to serious drawbacks resulting particularly from the
fact that the reheating destroys the previous annealing of the glass at the upper
part abcd which has been licked by the gas flame; the said annealing was
also spoiled to a great extent by the cutting to size.
The annealing having thus been rendered ineffective by the above operation,
the result will be a considerable breakage during the operation and after the same.
This breakage may amount in a short time to as much as 40 and 50 per cent., and
is characterized especially by the fact that the upper edge becomes detached, even
without shock, along the line cd. This drawback is obviated by hardening the
edges by a process similar to the process hereinbefore described, and the said
method of hardening the edges has not only the great advantage of imparting
to goblets, foot glasses &c., a great strength in the edges, but also of completely
preventing the said great breakage.
The hardening of the edges is effected as follows: The heat of the blowpipe
or reheating furnace is utilized by placing over it the vessel containing the

page_text: hardening bath which is rendered liquid by the waste heat of the blowpipe. A
mass of spongy material such as sponge, cloth or other similar substance dips
in the vessel and is at the same time attached thereto or suspended by means
of a small cord, chain or other suitable device from the end of a lever arrangement
operated by a treadle in such a manner as to allow the workman to remove the
saturated spongy material at the desired moment from the vessel containing the
bath without having to move in any way.
The article having been reheated, the workman acts upon his treadle and
instantly raises the saturated spongy material into which he, by holding the
article and moving it forward horizontally dips those edges of the said article
which are to be hardened, without losing a moment of time, because all vertical
dipping would necessitate a movement of the body and a cooling of the article.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, I declare that what I
claim is:
1. A process for the manufacture of hardened class, more particularly adapted
to goblet ware cast or pressed, smooth or cut, characterized by the annealing,
prior to hardening, of the partially completed articles, the hardening being effected
after the cut has been roughed out on the iron wheel, substantially as described.
2. The application of the above specified process to the hardening of the edges
only of the glass ware, whereby the edges of the articles, after preliminary anneal-
ing, are subjected to reheating and then dipping, the article being held and moved
forward horizontally into a saturated spongy mass the bath for which is heated
by the waste heat of the blowpipe or reheating furnace a suitable treadle or other
device being provided for enabling the workman to raise the spongy mass from
the vessel at the desired moment, without moving, thus avoiding loss of time
which would cause a cooling of the article, substantially as and for the purpose
herein before described.
1000