An Improvement or Improvements in or Substitutes for the Flattening Stones Employed in the Flattening of Sheet Glass.
Year: 1894

page_text: Date of Application, 21st Mar.. 1894
Complete Specification Left, 16th Jan., 185-Accepted, 2nd Mar.,
1895
PROVISIONAL SPECIFICATION.
An Improvement or Improvements in or
Substitutes for the
Flattening Stones Employed in the Flattening of Sheet Glass.
We, CHANCE BROTHERS AND CO. LIMITED, of West Smethwick in the
County of Stafford, Glass Manufacturers and JOSEPH EDWARD SCOTT, of
No. 3 High Street, West Bromwich, in the County of Stafford, Works Manager,
do hereby declare the nature of this invention to be as follows
The flattening stones ordinarily employed in the flattening of sheet glass consist
of a flat slab of natural stone or of burnt fire clay the surface of which has been
made approximately true. Glass flattened on the surface of the said stones is
generally more or less injured by markings and in some cases spoiled thereby.
In order to prevent the marking of the glass in the process of flattening it has
been customary to place on the said stone a "lagre," that is, a sheet of glass of a
size larger than that of the sheets of glass to be flattened the upper surface of
which lagre has been coated with a protective material to prevent the sticking of
the said lagre and the sheets of glass flattened on it together.
The object of the said invention is to make flattening stones or substitutes for
flattening stones in the manner hereinafter described by the use of which the
marking of the glass is wholly or in great part obviated.
We make a metal slab, preferably a cast iron slab, the under surface of which
has ribs formed on it in the casting process for the purpose of preventing warping.
We plane the upper surface of the said slab and treat the planed surface in the
following way.
We heat the slab to a dull red heat so as to burn off any grease
thereon. The heating of the slab has also the advantage of making the surface
slightly rough so that the coating hereinafter described adheres better thereto.
When the slab is cool we coat its upper or flat surface with dark purimachos mixed
with water to about the consistency of molasses. The dark purimachos we employ
is a fire resisting cement largely used in the building of furnaces and for other
purposes where a heat resisting material is required and is a well known article of
commerce. Before the said coated surface is quite dry we apply a coating of a
mixture of dark purimachos and powdered bone ash, or other earthy phosphate in
the proportion of about three parts by measure of dark purimachos to two of
powdered bone ash, the said materials being mixed with water to the consistency
of molasses. Before the last named coating is quite dry we prefer to apply a third
and afterwards a fourth coating of the said mixture of purimachos and powdered
bone ash but the number of coatings may be varied according to the thickness of
each coating.
When the last coating is quite dry the surface is made true by rubbing with an
iron rubber and with coarse and afterwards fine sand. The surface is then polished
with a glass rubber and emery in fine powder and the treated slab is finished by
burning.
If after the burning process any roughness or defect in the surface is discovered
the said surface is repolished in the way herein before described.
Although we prefer to use dark purimachos as herein before described yet other

page_text: fire resisting cements or clays may be used in place of the said dark purimachos
with the same or nearly the same effect.
Dated this 21st day of March 1894.
W. T. WHITEMAN,
Agent for the Applicants.
An Improvement or Improvements in or Substitutes for the
Flattening Stones Employed in the Flattening of Sheet Glass.
We CHANCE BROTHERS AND CO. LIMITED, of West Smethwick, in the
County of Stafford, Glass Manufacturers and JOSEPH EDWARD SCOTT, of
No. 3 High Street, West Bromwich in the County of Stafford, Works Manager,
do hereby declare the nature of the said invention and in what manner the same is
to be performed to be particularly described and ascertained in and by the following
statement :-
The flattening stones ordinarily employed in the flattening of sheet glass consist
of a flat slab of natural stone or of burnt fire clay the surface of which has been
made approximately true. Glass flattened on the surface of the said stones is
generally more or less injured by markings and in some cases spoiled thereby.
In order to prevent the marking of the glass in the process of flattening, it has
been customary to place on the said stone a "lagre," that is, a sheet of glass of a
size larger than that of the sheets of glass to be flattened the upper surface of
which lagre has been coated with a protective material to prevent the sticking
together of the said lagre and the sheets of glass flattened on it.
The said invention consists in making flattening stones or substitutes for
Hattening stones in the manner hereinafter described by the use of which the
marking of the glass is wholly or in great part obviated and the lagres referred to
rendered unnecessary.
In making according to the said invention a substitute for the flattening stones
ordinarily employed in the flattening of sheet glass we proceed as follows
We make a metal slab preferably of cast iron the under surface of which has
ribs formed on it in the casting process for the purpose of obtaining strength with
lightness and for preventing the warping of the slab by changes of temperature.
We plane the upper surface of the said slab in an ordinary planing machine and
after having made the said upper surface a practically true plane, we groove the
said surface by finally planing it in a series of fine parallel grooves say six or seven
to the inch. The coating applied as hereinafter described attaches itself more
securely to a grooved than to an ungrooved surface. We treat the planed and
grooved surface in the following manner.
We heat the slab to a dull red heat so as to burn off any grease which may be
on it.
The heating of the slab has also the advantage of making the surface
slightly rough so that the coating bereinafter described adheres the better thereto.
The slab may be heated in a muffle or heated chamber and after heating is
slowly cooled by the spontaneous cooling of the said muffle or chamber, so as to
leave the slab in an annealed state.
We coat the upper flat surface of the cooled slab with dark purimachos mixed
with water to about the consistency of molasses. The dark purimachos we employ
is a fire resisting cement largely used in the construction and repairing of furnaces,
gas retorts and bakers' ovens and for other purposes where a heat resisting
material is required. The said purimachos is a well known article of commerce.
We apply the mixture of purimachos and water by means of a soft brush.
Before the coated surface is quite dry we apply a coating of a mixture of dark
purimachos and powdered bone ash in the proportion of about three and a half

page_text: pounds of dark purimachos to twelve ounces of powdered bone ash, the said
inaterials being mixed with water to the consistency of molasses and applied in the
manner described with respect to the first coating. Before the last named or
second coating is quite dry we prefer to apply a third and afterwards a fourth
coating of the said mixture of purimachos and powdered bone ash but the number
of coatings may be varied according to the thickness of each coating.
The first coating as well as the subsequent coatings may consist of a mixture of
purimachos and bone ash.
We do not limit ourselves to any particular thickness of the combined coatings
but in practice we have found that a thickness of one thirty second of an inch in
the combined coatings answers well. In applying the coatings of purimachos and
powdered bone ash we proceed in the following manner. We first mix the
purimachos with water to the consistency of molasses; we then add the bone ash,
stirring the mixture so as to thoroughly incorporate the materials and adding
from time to time sufficient water to preserve in the mixture the consistency of
molasses.
In order to secure the more effectual incorporation of the materials we prefer to
let the mixture stand three or four days before using it. The water lost by
evaporation is replaced but we do not add more water than is sufficient for the
convenient spreading of the mixture on the slab.
When the last coating is quite dry the surface is made true by rubbing with an
iron rubber and with coarse and afterwards fine sand. The treated slab is finished
by burning. The burning process consists in heating the coated slab to a dull red
heat. The said coating is thereby thoroughly dried and hardened and at the same
time attached to the slab.
If, after the burning process, any roughness or defect in the surface is discovered
the said surface is rubbed with fine sand in the way hereinbefore described.
In order that the said invention may be the better understood we have
represented in the accompanying drawing a slab or substitute for a flattening stone
made according to our invention.
Figure 1 represents a plan of the underside of the slab; Figure 2 a longitudinal
section through the middle of the said slab and Figure 3 a cross section through
the middle of the slab.
On the underside of the slab a are four or other number of radiating tapering
ribs b, b, b, the said ribs terminating in the marginal rim c. e is the combined
coating of purimachos and powdered bone ash.
We do not limit ourselves to any particular construction of the slab a for
example the ribs b, b, b, b may be dispensed with as illustrated in Figure 4. In
this case the slab a is made somewhat thicker at its middle than when the
radiating ribs are used and tapers towards its marginal flange as represented in the
drawing.
Slabs made according to the said invention may be fitted to the carriages
ordinarily used in flattening glass.
The slab should be supported on the carriage preferably at four points by packing
pieces inserted between the flange of the slab and the carriage at about a distance
from each end of each longer side of the slab equal to one fifth of the whole length
of the slab.
If during the use of the slab sinking occurs at any point or points of the slab the
level of the said slab may be restored by introducing a packing piece or packing
pieces under the sunken part or parts. The iron under the heat of the flattening
furnace will yield sufficiently to regain its level by the action of the said packing
pieces.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed we declare that we
claim as our invention :-
The improvement or improvements in or substitutes for the flattening stones

page_text: employed in the flattening of sheet glass herein before described and illustrated in
the accompanying drawing; that is to say, a metallic slab preferably of cast iron
the upper or acting surface of which has been coated with the mixture or composition
described substantially as and for the purpose set forth.
Dated the Sixteenth day of January 1895.
W. T. WHITEMAN,
Agent for the Applicants.