Improved Apparatus for Silvering or Coating Mirror-glass.
Year: 1896

page_text: PROVISIONAL SPECIFICATION.
Improved Apparatus for Silvering or Coating Mirror-glass.
I, CARL LUDWIG ERLWEIN of No. 6, Akazienstrasse, Schoeneberg near
Berlin, Prussia in the Empire of Germany, Doctor of Philosophy, do hereby
declare the nature of this invention to be as follows:-
My invention relates to an improved apparatus for silvering or coating mirror-
glass, and the object of my invention is to provide an apparatus by which the
plate or plates or articles of glass to be coated or silvered, when placed on the
surface of the apparatus, may be brought to a perfectly uniform temperature,
the desired uniform temperature being obtained by heating and cooling, as required,
and the said apparatus is equally constructed to distribute the solution from which
the metal is to be precipitated, in a perfectly even and uniform state all over the
plate or plates or articles to be coated.
By many trials made in recent times, it has been proved, that a good mirror of
perfect and true reflection and of intensive brightness can only be obtained by a
perfectly uniform precipitate, and to obtain the utmost degree of uniformity it is
of the greatest importance, that the desired temperature may be raised or lowered,
as required; and by determining the exact degree of uniform temperature existing
throughout the whole and entire surface of the apparatus, the operator further, is
enabled to accelerate or retard the precipitation, in accordance with the requirements
of the process to be performed, to obtain mirrors of varying quality or more or less
intensity of reflection.
In carrying out the invention, I provide a frame, preferably of wood on which is
carried a case, preferably of cast-iron, tightly covered by a wrought-iron plate, the
upper surface of which is carefully planed and finished. The said surface is then
covered by a rubber-plate, which is tightened to the said surface by means of ledges
and screws to the sides of the case, said ledges and screws allowing the rubber-
plate to be easily removed and adjusted for the purpose of cleaning.
Two or more pipes enter the said case, one of said pipes being provided with a
gauge-glass, the other with a suitable cock, said pipes being perforated to discharge
cold water in fine jets. At or near the centre of the case, a suitable discharge
pipe is provided in the bottom, said pipe having a stop-cock or valve. To
provide for the escape of air when the case is being filled, a suitable cock or
valve is arranged below the covering plate, thus allowing the case to be filled to
the top.
At or near two opposite sides of the case, steam inlet-pipes, preferably of copper,
are arranged, provided with suitable valves. From the said inlet-pipes a suitable
number of branch-pipes extend through the case projecting from the opposite side
and leading to pipes provided with suitable cocks or valves, and serving to collect
the water of condensation of the steam. The water of condensation, being obtained
and drawn from these cocks or valves, is of great purity and offers a particular
advantage in the further treatment of the mirror-glass obtained, as the glass,
previous and subsequent to the silvering operation, must be well cleansed or
washed with distilled water of perfect purity. The distilled water obtained, further,
is of particular use in preparing the solution of silver, from which the precipitate
is to be drawn, the said solution requiring distilled water of perfect purity.

page_text: The case is surrounded by a sheet-metal channel, carried by a wooden frame, the
said channel serving to receive the fluid solution, which, when the precipitate has
been formed, is caused to flow off.
By means of adjusting screws, carried by the frame, the case may easily be
adjusted into a completely horizontal position, and the rubber-plate thereby equally
established horizontally.
To operate the silvering or coating of mirror-glass by the aid of the before
described apparatus, I proceed as follows:
Having first opened the air escape cock, I fill the case up to a certain height
with water, fed through the pipes which enter the case, after which the stop-cocks
of the feed-pipes and the air escape cock are closed. Thereupon I open the steam
inlet-valves admitting steam into the pipes and branch pipes within the case. By
the said steam-pipes, entering from opposite sides, the temperature of the water
contained within the case is uniformly raised, and accordingly also the temperature
of the top or cover-plate and rubber plate tightened thereto will be uniform. The
plate or plates or articles of glass to be silvered, being placed upon the rubber plate,
and the solution of silver distributed over the surface of such plate or plates or
articles of glass, are equally subjected to the corresponding, perfectly even and
uniform increase of temperature. The said temperature may be further raised or
reduced, as desired, by a further admittance of steam or cold water through the
respective pipes as the case may be, to answer any requirement of the chemical
process to be performed, or the quality of the precipitate to be obtained. To
accelerate the establishment of a uniform temperature within the case, a stirring or
agitating device of any suitable kind, is provided. The plate or plates or articles of
glass to be silvered are placed upon the rubber plate as soon as the latter has obtained
the temperature determined to correspond to the nature of the solution to be
applied, the said temperature being easily controlled by thermometers placed at
different parts. The plate or plates of glass, before being placed upon the rubber
plate, are carefully cleaned and polished by suitable means, and previously heated
to a moderate degree. The solution is then poured on and distributed on the
surface, which distribution is automatically obtained by the perfectly horizontal
position of the surface. The temperature of the whole surface being precisely the
same, owing to the reasons before described, the precipitate obtained must be the
same all over the entire surface of the glass under treatment, and consequently,
the faculty of reflection of the mirror or mirrors produced is perfectly uniform.
As has been described before, the temperature of the solution, after having been
poured on, may, still, be increased or lowered, according to the nature of the
process to be performed aud to the quality of intensity to be obtained.
Dated this 11th day of March 1896.
WM. P. THOMPSON & Co.,
Of 6 Lord Street, Liverpool, Agents.
COMPLETE SPECIFICATION.
Improved Apparatus for Silvering or Coating Mirror-glass.
I, CARL LUDWIG ERLWEIN of No. 6, Akazienstrasse, Schoeneberg near
Berlin, Prussia, in the Empire of Germany, Doctor of Philosophy, do hereby
declare the nature of this invention and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement :-
My invention relates to an improved apparatus for silvering or coating mirror-
glass, and the object of my invention is to provide an apparatus by which the plate
or plates or articles of glass to be coated or silvered, when placed on the surface

page_text: of the apparatus, may be brought to a perfectly uniform temperature, the desired
uniform temperature being obtained by heating and cooling, as required, and the
said apparatus is equally constructed to distribute the solution fron which the
metal is to be precipitated, in a perfectly even and uniform state all over the plate
or plates or articles to be coated.
By many trials made in recent times, it has been proved that a good mirror of
perfect and true reflection and of intensive brightness can only be obtained by a
perfectly uniform precipitate, an to obtain the utmost degree of uniformity it is
of the greatest importance, that the desired temperature may be raised or lowered,
as required, and by determining the exact degree of uniform temperature existing
throughout the whole and entire surface of the apparatus, the operator further, is
enabled to accelerate or retard the precipitation, in accordance with the requirements
of the process to be performed, to obtain mirrors of varying quality or more or less
intensity of reflection.
The improved apparatus of my invention is represented in the accompanying
drawings, in which Figure 1 is a vertical section and Figure 2 a plan of the
same.
A frame A A¹, preferably of wood carries a case k, preferably of cast iron,
tightly closed by a wrought iron plate 6, the upper surface of which case is care-
fully planed and finished. The said surface is covered by a rubber plate c, which
is tightened to the said surface by means of ledges ¹ screwed to the sides of the
case k, said ledges and screws allowing the rubber plate to be easily removed and
adjusted for the purpose of cleaning.
Two or more pipes d d enter the said case, one of said pipes being provided
with a gauge glass W, the other with a suitable cock el, the said pipes d d being
perforated, as shown, to discharge cold water in fine jets. At or near the centre
of the case k a suitable discharge pipe gis provided in the bottom, said pipe having
a stop cock or valve h. To provide for the escape of air when the case k, is being
filled, a suitable cock or valve f, is arranged under the top plate of the case k, thus
allowing the case to be filled to the top. At or near two opposite sides of the
case k, steam inlet pipes, preferably of copper, are arranged provided with
suitable valves and . From the said inlet pipes a suitable number of branch
pipes 9 extend through the case k and project from the opposite side and lead to
pipes n n provided with suitable cocks or valves m m' serving to collect the water
of condensation of the steam. The water of condensation obtained and drawn.
from these cocks or valves m m' is of great purity and offers a particular advantage
in the further treatment of the mirror-glass obtained, as the glass, previous and
subsequent to the silvering operation, must be well cleaned or washed with
distilled water of perfect purity. The distilled water obtained is further of
particular use in preparing the solution of silver, from which the precipitate is to
be drawn, the said solution requiring distilled water of perfect purity.
The case is surrounded by a sheet metal channel a¹ carried by a wooden
frame o o', the said chanuel serving to receive the fluid solution, which, when the
precipitate has been formed, is caused to flow off.
By means of the adjusting screws j j¹ carried by the frame A A¹, the case k
may easily be adjusted into a completely horizontal position, and the rubber
plate c, of course, is thereby also adjusted into a completely horizontal position.
To operate the silvering or coating of mirror-glass by the aid of the before
described apparatus, I proceed as follows:-
d
9
Having first opened the air escape cock f, I fill the case k up to a certain height
with water fed through the pipes & d' after which the stop cocks of the feed pipes
and the cock fare closed. Thereupon I open the steam inlet valves i, admitting
steam into the pipes and branch pipes within the case k. By the said steam
pipes entering from opposite sides the temperature of the water contained within
the case is uniformly raised, and, accordingly, also the temperature of the top or
cover plate and the rubber plate tightened thereto will be uniform. The plate or
plates or articles of glass to be silvered, being placed upon the rubber plate, and

page_text: the solution of silver distributed over the surface of such plate or plates or articles
of glass, are equally subjected to the corresponding perfectly even and uniform
increase of temperature. The said temperature may be further raised or reduced,
as desired, by a further admittance of steam or cold water through the respective
pipes as the case may be to answer any requirement of the chemical process to he
performed, or the quality of the precipitate to be obtained. To accelerate the
establishment of a uniform temperature within the case k, a stirring or agitating
device of any suitable kind, as indicated by a a', is provided. The plate or plates
or articles of glass to be silvered are placed upon the rubber plate c as soon as the
latter has obtained the temperature determined to correspond to the nature of the
solution to be applied, the said temperature being easily ascertained by thermometers
placed at different parts. The plate or plates of glass, before being placed upon
the rubber plate, are carefully cleaned and polished by suitable means, and
previously heated to a moderate degree. The solution is then poured on and
distributed on the surface, which distribution is automatically obtained by the
perfectly horizontal position of the surface. The temperature of the whole surface
being precisely the same, owing to the reasons before described, the precipitate
obtained must be the same all over the entire surface of the glass under treatment,
and, consequently, the faculty of reflection of the mirror or mirrors produced is
perfectly uniform.
As has been described before, the temperature of the solution, after having been
oured on, may still be increased or lowered according t the nature of the process
to be performed and to the quality to be obtained.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. An apparatus for silvering or coating mirror-glass, comprising a case having
a plane cover, steam feed pipes entering the said case from two opposite sides, and
water pipes perforated inside the said case for the distribution of cold water,
substantially as and for the purpose set forth.
2. An apparatus for covering or coating mirror-glass comprising a horizontally
adjustable case having a plane surface, steam feed pipes entering said case from
opposite sides, water pipes perforated inside the said case and stirring apparatus,
substantially as and for the purpose set forth.
3. An apparatus for silvering or coating mirror-glass, comprising a case having
a plane surface, steam feed pipes entering the said case from opposite sides, water
pipes perforated inside the said case, a rubber plate tightened to the surface of the
said case and a channel surrounding the same, substantially as and for the purpose
set forth.
4. An apparatus for silvering or coating mirror glass, comprising a horizontally
adjustable case having a plane surface, steams feed pipes entering the said case from
opposite sides, water feed pipes perforated within the said case, stirring apparatus
a rubber plate tightened to the surface of the case and a channel surrounding the
same, substantially as aud for the purpose set forth.
Dated this 1th der of December 1806
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant.