IMPROVEMENTS IN AND IN CONNECTION WITH THE DECORATION OR PRODUCTION OF DESIGNS ON GLASS AND GLASS WARE communicated
Year: 1883

page_text: T
LETTERS PATENT to John Thomson King of Liverpool in the County of
Lancaster Patent Agent for an Invention of "IMPROVEMENTS IN AND IN
CONNECTION WITH THE DECORATION OR PRODUCTION OF DESIGNS ON GLASS
AND GLASS WARE communicated to him by Hermann Schulze-Berge at
present residing at Pittsburgh Pennsylvania, one of the United States of
America"
PROVISIONAL SPECIFICATION left by the said John Thomson King at the
Office of the Commissioners of Patents on the 4th May 1883.
"
JOHN THOMSON KING of Liverpool in the County of Lancaster. Patent Agent,
"IMPROVEMENTS IN AND IN CONNECTION WITH THE DECORATION OR PRODUCTION
OF DESIGNS ON GLASS AND GLASS WARE [communicated to him by Hermann
Schulze-Berge at present residing at Pittsburgh Pennsylvania, one of the United
States of America"]
My invention (as communicated) relates to the decoration of glass and glass
ware by a process analagous to that of etching, and is designed to obviate the use
of liquid hydrofluoric acid in the process of etching, and to obtain clearer and more
delicately traced etching on glass than can be produced by the use of that fluid as
heretofore practiced.
The process heretofore usually employed in the etching of glass, consists in the
exposing of those portions of the glass surface to be etched to the direct action of
liquid hydrofluoric acid, the remainder of the glass surface being "stopped off" or
protected from the mordant action of the acid by a coating of wax or other
substance similarly capable of resisting such action. In that process the glass
surface is coated with a thin film of the stop off material and the drawing or design
is sketched by an etching needle so as to expose the lines so drawn to contact with
the acid.
By my process the design or drawing to be etched on the glass may, if preferred
be sketched by hand, but this is not necessary as it may be printed, or impressed
upon the surface to be decorated, or may be applied thereto by means of transfer
sheets, or by reticulated fabrics impregnated with the etching material, so that I am
[Price Bd1

page_text: enabled to produce the most delicate patterns and designs, and to reproduce them
in fac simile indefinitely, without resorting to the tedious and expensive method of
hand drawing.
These results I am enabled to accomplish by use of a solid instead of a liquid
substance as the etching agent, which being finely comminuted is either mixed with
some suitable vehicle and used as a printing ink, or dissolved in water or other
menstruum, and applied by means of suitable fabrics impregnated therewith, or
applied as a fine powder, as hereinafter described. The article of glass ware is then
subjected to a firing process, whereby a chemical reaction is set up which results in
the etching of the glass.
For this purpose I employ some of the solid salts of fluorine, or fluorides of the
alkaline earths or fluoride of ammonium. The fluorides of the fixed alkalies, as
fluoride of sodium or fluoride of potassium are the compounds of fluorine which
I prefer to use, and these may be used, if preferred in admixture with the fluorides
of alkaline earths or with fluoride of ammonium.
In thus using the solid fluorides they are first dried and then reduced to a finely
pulverized condition The more perfect the reduction the better will be the
result.
.
If the fluoride is to be used as an ink for printing, writing or sketching on the
surface of the glass, it must be mixed in a finely powdered state with a suitable
vehicle and thoroughly incorporated therewith. This vehicle should be some moist
and viscid substance, capable of adhering to the surface of the glass without
running, so as to preserve the lines of the pattern design or writing to be impressed
or traced thereon, and of forming an intimate and thorough mixture with the dry
and pulverized fluoride. For this purpose a resinous substance of the proper
consistency such as Venice turpentine or other resin dissolved in some volatile
solvent may be used, or a solution of resin and bees wax in turpentine, or a
mixture of water and glycerine, or even undissolved fat, paraffine wax, or soap may
be used, though I prefer the Venice turpentine, which can be readily reduced
to the proper consistency. I do not however desire to confine myself to the use of
any particular form of vehicle, as various other substances might be named for this
purpose, the requisite conditions being besides those before named, that they should.
be adapted to tracing painting, drawing or printing the proposed design on the
glass and contain no ingredient which when exposed to the subsequent treatment
would either decompose or permanently stain the glass, and also that it will
decompose by the action of the heat to which the glass is afterwards exposed
without removing or displacing the deposite of fluoride.
Such mixture of fluorides with a vehicle I shall hereafter for the sake of
convenience call fluoride ink.
Instead of using the fluorides of the fixed alkalies alone, other compounds or
mixtures containing fluorine may be employed in my process, such for example as
the fluorides of the alkaline earths, cryolite, and even volatile fluorides such as
fluoride of ammonium.
It is not desirable to use the fluorides of alkaline earths alone, if indeed they can
be so used, because they do not act upon the glass below a temperature at which
glass is apt to begin to soften, but by mixing them with the fluorides of the fixed
alkalies (as fluoride of sodium) the compound will react on the silica of the glass at
a sufficiently low degree of heat to prevent any danger of the glass becoming
deformed thereby.
The fluoride ink thus prepared is then applied to the surface of the glass to be
etched, which should first be made thoroughly clean. It may be used with a pen,
or with a brush when the design is to be drawn by hand, or it may be applied
with a stencil plate and brush, or it may be printed upon the glass by means of a
disc or plate of soft rubber on which the desired design or letters are impressed in
relief. It may also be applied by means of transfer pictures or designs, the mode
of preparing and applying which I will hereafter describe.
In preparing the fluoride ink, especially where it is intended to be used for drawing

page_text: on the glass by hand, it may be desirable to mix some coloring matter with it so
that the painter or designer may be able to see the effect of his work. In such
case some aniline coloring matter may be mixed with the vehicle, which will be.
removed by the subsequent treatment and leave no permanent mark on the glass.
If it is desired to color the glass permanently as well as etch it, finely pulverized
fusible metallic colore may be mixed into the vehicle together with the fluoride.
There is another method in which the fluorides may be applied to the glass
without mixing them previously with any vehicle to form an ink. The desired
pattern design or picture may be traced stamped or sketched by hand on the
surface of the glass with a resinous varnish or with some of the substances herein-.
before mentioned as a vehicle for the ink, and then while the design so applied to
the glass is sufficiently moist or sticky, the fluoride or mixture of fluorides in a
finely powdered condition is dusted over the glass, when it will adhere to the
sticky portions of the surface.
Still another method of applying the fluorides to the glass has the advantage of
dispensing with the use of a sticky vehicle, and of distributing the fluoride more
evenly over the surface of the glass. As the fluorides of the alkalies are soluble
in water, an aqueous solution may be used, which if desired can be thickened by
the addition of a very small quantity of mucilage or glycerin. Such solution may.
be applied with a pen, brush or stencil. The surface to which it is applied should
then be warmed so as to evaporate the water, when a deposit of solid fluoride will
be found attached to the glass. This deposit being in the form of minute crystals,
when it is afterwards exposed to the requisite degree of heat to produce the
required reaction, the water which is enclosed between the crystals is driven off,
and the deposited salts are apt to fall away from the glass: An addition of
mucilage to the solution does not entirely obviate this difficulty, and hence it is
better, as soon as the drawing on the glass is sufficiently dry, to cover the
decorated surface with a very thin film of resinous varnish, by which the difficulty
is obviated
By means of an aqueous solution as just described, fluoride of ammonium may be
used in my process, but it cannot be used mixed with a resinous vehicle, because it
volatalizes at a temperature requisite to burn away the varnish: but when the
varnish is laid as a thin filin over the deposited fluoride of ammonium this difficulty
does not interfere with its action.
Fluoride of ammonium does not produce as great a degree of opacity on the glass
in the etching, as do the fluorides of the fixed alkalies, and this fact may be taken
advantage of to produce artistic effect in fine work; different degrees of opacity
being produced in different portions of the saine etching, by a skillful application to
some parts of the design or solution of fluoride of ammonium, to other parts a
solution of the fluorides of the fixed alkalies, and to other parts a mixture of the
Hluorides of the fixed alkalies and of the alkaline earths mixed with oil or other vehicle
which will not require the same degree of heat. to remove it as varnish does. A
variation of effect may also be produced by using a different proportion of the
fluoride in making the solution or ink to be applied to different portions of the
work.
In making these mixtures and solutions of fluorides with a vehicle or with a
menstruum I have not given any proportions, as that will depend on the degree of
opacity desired to be produced on the glass. For example in making an aqueous
solution it may be saturated or not as may be preferred. The fluorides may also
be mixed together, as fluoride of the fixed alkalies, with the fluorides of the
alkaline earths or with the fluoride of ammonium.
As the different fluorides produce different degrees of opacity in the finished
work my process affords the opportunity of producing effects which cannot be
attained by the ordinary stop off method of etching with liquid hydrofluoric acid
In this connection it may be well to notice that the degree of heat applied in the
subsequent part of my process has an effect on the opacity of the etching, and that,
this also varies according to the different fluorides employed, as well as with the

page_text: different mixtures of fluorides.
For example when the fluorides of the fixed
alkalies are employed the opacity produced passes away if the final heat is continued
for a longer time than ordinary and this too varies with the amount of silica
contained in the glass, in which respect different kinds and makes of glass vary
considerably. It is therefore impossible to give any definite rule to govern the
amount or proportions of fluoride to be used to produce any given effect, but a
little care and experience on the part of the workman will enable him to utilize
these variations of temperature ingredients and proportions with admirable effect.
A very pretty effect may be produced in the etching of glass ware by my process,
by the use of threads or reticulated thread fabrics such as lace blonde and similar
articles which have sufficient interstices between the threads to produce a distinct
pattern on the glass. For this purpose the lace or other material should be made
of vegetable fibre, or of silk, other animal threads or hair being unsuitable for the
purpose. The threads or lace to be so used should be previously washed in order
to remove any foreign matter which might discolor the article to be ornamented.
If the threads or lace be made of cotton they may if preferred be first treated
with nitric and sulphuric acids, and then washed, in the well known method of
converting cotton into dinitro celluloid, the advantage of which is that the threads
thereby acquire a sharper outline and become more readily combustible, and after
combustion leave little or no ash. Linen fabrics may be used, but they do not yield
as good a result as silk or cotton. The threads of which the lace is composed should
not be tightly twisted, and should be of as uniform thickness as possible, and the
finer the threads the better the result. Wide meshed lace is preferable to that in
which the interstices are smaller.
The threads, or lace previously treated as above described, are then immersed in
an aqueous solution of some of the fluorides before mentioned, or a mixture of
them, or in a fluoride ink prepared as has been stated, and after becoming
thoroughly impregnated therewith the threads or lace are dried, and are then ready
for application to the glass. For this purpose the surface of the glass or that part
of it which is to be ornamented, is covered with a thin film of some transparent
and quick drying varnish. The threads (if separate threads are used) or the lace
fabric, impregnated as before described, is then carefully applied to. and pressed
upon the varnished surface care being taken that each thread, and every part of
the fabric is closely adherent to the surface of the article. It is then ready to
receive the subsequent treatment.
I will now proceed to describe the method of preparing and applying transfer
pictures or designs for etching by my process.
The selection of the basis of the sheet on which the transfer picture or design is
to be produced will depend on whether it is to be removed from the glass before
or after the final process of etching. If it is to be removed before the final process,
then the best way to do it is by wetting the transfer sheet, in which case a thin
paper is used as the foundation of the picture. The paper should either be unsized
or have very little sizing in it. It is first covered with a slight coating of some
mucilage which is soluble in water. When the mucilage is dry a thin film of
collodion (etherial solution of pyroxylin) or of resin dissolved in ether, and when
this also is dry the picture or design is printed or drawn on the collodion or
resinous surface. The object of using a coating of soluble mucilage first and then
of collodion or resin is that the paper may be removed by water leaving the
film of collodion or resin with the design thereon, attached to the glass, and that
the coating of collodion or resin may be removed by the subsequent application of
beat, so as to leave only the design in fluoride attached to the glass.
As it is a delicate and rather difficult operation to remove the paper basis from
the glass without disturbing the design, a basis may be used of some substance
which can be burned away without injury to the design underneath it: ordinary
paper in burning will curl and shrivel while still partially adherent to the collodion
or resinous-filio, and is very apt in so doing to injure the design, but there is a
description of paper known as "Japanese fibre paper" which is very thin and yet

page_text: sufficiently strong to receive the design, and which may be used without any
previous preparation, unless the fibres are too open, in which case it should receive
a thin coating of collodion, or similar substance which will give it a sufficiently
smooth and unbroken surface to receive the design drawn or painted thereon with
fluoride; fat, starch, mucilage or gelatine may be used instead of the collodion for
this purpose, but if starch, mucilage or gelatine are used the coating should be very
thin, as they are apt to form so thick a cuticle as to form blisters when the volatile
portions of the varnish used to apply the the picture, are evaporated by the heat.
A mixture of collodion and resin I have found serviceable for this purpose, as, it
renders the paper tougher, and is dissipated by the heat without injury to the
design
Collodion itself forms a good basis for the transfer picture but in order to bear
handling, so that the transfer pictures may be sold as articles of manufacture it
should be spread upon some thin fibrous vegetable tissue such as paper made of
very fine cotton fibre, or gauze or fine blonde.
Sheets may also be made from any finely reticulated fibrous substance of cotton
or silk, the interstices being first closed with varnish, starch, gelatine or fatty
matter wbich will give a smooth surface but which will be readily evaporated,
melted or charred by heat.
In order to cover sheets of Japanese fibre paper or other vegetable silken textile
fabric with a thin film of collodion, or of a mixture of collodion with resinous
substances dissolved in ether, such sheets should be stretched on a frame, and the
collodion or collodion mixture be applied with a sponge. This must be done
quickly because the sheet softens an application of the etherial solution. A quicker
method is to place the sheet smoothly on a pane of glass and apply the collodion &*
with a sponge or brush: after the ether has evaporated the sheet is removed from
the pane of glass by immersion in water for about ten minutes more or less. The
sheet of fibre paper thus coated, after being dried is ready to receive the desired
design. Sheets of collodion, without the paper basis, may be made in like manner
on a sheet of glass and separated therefrom by wetting; they are better if the
collodion be mixed with some resinous substance. Sheets made of a solution of
resin in ether may also be similarly prepared, but these and the collodion sheets
require a longer immersion in water to separate them from the glass than when
they have a basis of paper.
On the sheet thus prepared the desired design or picture may be sketched printed
or stamped with fluoride ink prepared as before described, or with an aqueous
solution of the fluoride or fluorides, thickened if necessary to the desired consistency
as already stated.
After the design has been produced in fluoride ink or solution on the prepared
transfer paper, and when it is thoroughly dry it should receive a protecting coat,
the character of which will depend upon the character of ink used. If the vehicle
used in making the ink is a resinous or fatty substance the picture should be coated
with a thin film of collodion, varnish mucilage or starch. If the drawing was made
with a solution of a fluoride salt, the coating should be a thin film of a resinous
solution. Such coating is not however always necessary. Care should be taken to
make all the films or coatings of collodion or resinous substances whether above or
below the design or picture as thin as possible, so as to prevent the derangement
of the particles of fluoride which compose the design, by the evaporation or charring
of those substances.
Transfer pictures, patterns or designs thus prepared are applied to the surface, of
the glass to be etched in the following manner.
The glass surface to receive the transfer picture should first be made thoroughly
clean and dry, then a thin coating of some quick drying varnish is applied either to
the glass or to the transfer picture, and the picture is laid face down in proper
position on the glass surface and pressed firmly down thereon, so as to prevent the
interposition of bubbles of air, and to secure a perfect contact and adhesion between
the two surfaces. If the transfer picture had received a coating of varnish which

page_text: had become hard before the transfer picture is used, both the picture and glass
should be varnished before the picture is laid on.
If the transfer picture has been made on a basis of paper or other material with
a film of mucilage interposed between it and the collodion or resinous film on which
the picture is made, the glass is then immersed in water for a sufficient time (ten
minutes more or less) to cause the mucilage to dissolve when the paper will separate
from the base of collodion or resinous substance, and will float off, leaving the
design protected by the collodion or resinous substance adhering to the glass. The
glass is then carefully and thoroughly dried, and is then ready for the next stage
of the process.
I will now proceed to describe the final step in my process, by which the deposit
of solid fluoride on the glass, made in any of the methods herein before described is
'caused to act upon the glass so as to produce the desired etching. This effect is
produced by causing reaction to take place between the fluorine in the fluorides and
the silica in the glass, which in combining pass off as a volatile compound leaving
the glass in the condition known as etched.
But before this reaction commences, the fluorides must be separated from the
vehicle with which they were mixed, and brought into intimate contact with the
surface of the glass and the vehicle itself removed out of the way. Both of these
effects may be produced by the action of heat in a suitable furnace, or the first
effect, (removal of the vehicle) may be produced by furnace heat, and the latter by
the combined action of heat and sulphuric acid.
I will first describe the operation by the use of furnace heat alone.
The glass article with the design printed, sketched or applied thereto, either by
printing or sketching with fluoride ink, or with fluoride solution, or by dusting
comminuted fluoride on the design previously applied in varnish, or by means of
impregnated lace fabric or by the use of transfer pictures, or any other known way
is placed in a suitable oven or furnace which is only slightly warm: the heat of
the furnace is then gradually raised to about 250° Farenheit. The furnace is
kept at that temperature until the turpentine, ether and volatile substances used
in the process have been evaporated, this may take an hour or less according to
the quantity, of volatile matter employed. The heat of the furnace is then gradually
raised to 500° or 600° Fahrenheit until the more solid chiefly carbonaceous matter
of the vehicle, or transfer pictures, or lace fabrics is thoroughly charred and has
disappeared, leaving only the film of fluoride on the surface of the glass. If any
small particles of charred matter remain they will ordinarily do no harm.
At this stage of the process any change or correction of the design on the surface
of the glass may be made, as no etching has yet taken place.
The heat of the furnace is then still further raised to about 750° Fahrenheit,
until the article of glass shows of a dull red heat, which is sufficient to produce the
necessary reaction between the fluorine and the silica of the glass. Care must be
taken that the heat be not raised so high (or continued so long) as to melt the
glass, or soften it so much as to cause it to become misshapen. The length of time
during which the maximum temperature is maintained need be only a few minutes,
another reason for care in this regard is that the opacity produced by the fluorides
of the fixed alkalies, passes off and the etched surface assumes a blistered and frozen
appearance if the heat be too great or too long continued. Experience will soon
enable a skillful workman to discontinue when the desirable maximum of heat has
been attained, and when to begin to reduce it. The glass article should then be
cooled slowly.
The alternative method of. producing the necessary reaction between the fluoride
deposited on the glass and the silica in the glass is as follows:-
When the degree of heat sufficient to volatalize the lighter ingredients used in
applying the the fluoride to the glass and the further degree of heat necessary to char
'and consume the more solid matters has been reached and continued long enough
to remove those substances leaving only the deposited fluoride on the surface of the
glass, instead of raising the heat sufficiently to produce the reaction before referred

page_text: to, the article of glass in that condition is then exposed in the same, or some other
furnace to an atmosphere of hot vaporized sulphuric acid. The action of this hot
vapor on the fluoride deposited on the surface of the glass, is such as to create the
necessary reaction to produce the etching effect.
The sulphuric acid may be vaporized in the same furnace in which the glass has
been previously heated. and the temperature needs not to be raised above that
necessary to produce the vaporization of the acid, say about 620° to 650° Fahrenheit.
If preferred however the glass article may be removed from the first furnace to a
special furnace in which the sulphuric acid is vaporized, or the hot vapors of
sulphuric acid may be conducted into the furnace in which the glass receives its
first beating.
The advantage of using the hot vapor of sulphuric acid, to produce the reaction
referred to is that it does not require the glass to be exposed to as high degree of
heat, which is an important consideration in cases where, owing to the thinness of
the glass, or for other causes it is not desirable to subject it to a temperature of
750° Fahrenheit or thereabouts. It does not however produce as great a degree
of opacity in the glass as when the reaction is produced by the agency of a high
heat without the use of the acid vapor.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Thomson King in the Great Seal Patent Office on the
3rd November 1883.
JOHN THOMSON KING of Liverpool in the County of Lancaster, Patent Agent,
"IMPROVEMENTS IN AND IN CONNECTION WITH THE DECORATION OR PRODUCTION
OF DESIGNS ON GLASS AND GLASS WARE." A communication to him by Hermann
Schulze Berge at present residing at Pittsburgh, Pennsylvania one of the United
States of America."
My invention (as communicated) relates to the decoration of glass and glass ware
by a process analagous to that of etching, and is designed to obviate the use of
liquid hydrofluoric acid in the process of etching, and to obtain clearer and more
delicately traced etching on glass than can be produced by the use of that fluid as
heretofore practised
The process heretofore usually employed in the etching of glass, consists in the
exposing of those portions of the glass surface to be etched to the direct action of
liquid hydrofluoric acid, the remainder of the glass suface being "stopped off” or
protected from the mordant action of the acid by a coating of wax or other
substance similarly capable of resisting such action-In that process the glass
surface is coated with a thin film of the stop off material and the drawing or
design is sketched by an etching needle so as to expose the lines so drawn to
contact with the acid
By my process the design or drawing to be etched on the glass may, if preferred
be sketched by hand, but this is not recessary as it may be printed, or impressed
upon the surface to be decorated, or may be applied thereto by means of transfer
sheets, or by reticulated fabrics impregnated with the etching material, so that I
am enabled to produce the most delicate patterns and designs, and to reproduce
them in fac simile indefinitely, without resorting to the tedious and expensive
method of hand drawing.
These results I am enabled to accomplish by use of a solid instead of a liquid
substance as the etching agent, which being finely comminuted is either mixed
with some suitable vehicle and used as a printing ink, or dissolved in water or
other menstruum, and applied by means of suitable fabrics impregnated therewith,
or applied as a fine powder, as hereinafter described-The article of glass ware is
then subjected to a firing process, whereby a chemical reaction is set up which
results in the etching of the glass.
For this purpose I employ some of the solid salts of fluerine, or fluoride of the
alkaline earths or fluoride of ammonium-The fluorides of the fixed alkalies, as
fluoride of sodium or fluoride of potassium are the compounds of fluorine which I
prefer to use, and these may be used, if preferred in admixture with the fluorides
of alkaline earth, or with fluoride of ammonium
In thus using the solid fluorides they are first dried and then reduced to a finely
pulverized condition-The more perfect the reduction the better will be the result
If the fluoride is to be used as an ink for printing, writing or sketching on the
surface of the glass, it must be mixed in a finely powdered state with a suitable
vehicle and thoroughly incorporated therewith-This vehicle should be some moist
and viscid substance, capable of adhering to the surface of the glass without
running, so as to preserve the lines of the pattern design or writing to be impressed
or traced thereon, and of forming an intimate and thorough mixture with the dry
and pulverized fluoride-For this purpose a resinous substance of the proper

page_text: consistency such as Venice turpentine or other resin dissolved in some volatile
solvent may be used, or a solution of resin and bees wax in turpentine, or a mixture
of water and glycerine, or even undissolved fat, paraffine wax, or soap may be used,
though I prefer the Venice turpentine, which can be readily reduced to the proper
consistency I do not however desire to confine myself to the use of any particular
form of vehicle, as various other substances might be named for this purpose, the
requisite conditions being besides those before named, that they should be adapted
to tracing, painting, drawing or printing the proposed design on the glass and
contain no ingredient which when exposed to the subsequent treatment would
either decompose or permanently stain the glass, and also that it will decompose by
the action of the heat, to which the glass is afterwards exposed without removing
or displacing the deposit of fluoride.
Such mixture of fluorides, with a vehicle I shall hereafter for the sake of
convenience, call fluoride ink.
Instead of using the fluorides of the fixed alkalies alone, other compounds or
mixtures containing fluorine may be employed in my process, such, for example as
the fluorides of the alkaline earths, cryolite, and even volatile fluorides such as
fluoride of ammonium
It is not desirable to use the fluorides of alkaline earths alone, if indeed they.
can be so used, because. they do not act upon the glass below a temperature at
which glass is apt to begin to soften, but by mixing them with the fluoride, of the
fixed alkalies (as fluoride of sodium) the compound will react on the silica of the
glass at a sufficiently low degree of heat to prevent any danger of the glass becoming.
deformed thereby
The fluoride ink thus prepared is then applied to the surface of the glass to be
etched, which should first be made thoroughly clean. It may be used with a pen,
or with a brush when the design is to be drawn by hand, or it may be applied
with a stencil plate and brush, or it may be printed upon the glass by means of a
disc or plate of soft rubber on which the desired design or letters are impressed in
relief. It may also be applied by means of transfer pictures or designs, the mode of
preparing and applying which, I will hereafter describe
In preparing the fluoride ink, especially where it is intended to be used for
drawing on the glass by hand, it may be desirable to mix some coloring matter
with it so that the painter or designer may be able to see the effect of his work-
In such case aniline coloring matter may be mixed with the vehicle, which will be
removed by the subsequent treatment and leave no permanent mak on the glass.
If it is desired to color the glass permanently as well as etch it, finely pulveized
fusible metallic colors may be mixed into the vehicle together with the fluoride
There is another method in which the fluorides may be applied to the glass
without mixing them previously with any vehicle to form an ink-The desired
pattern design or picture may be traced, stamped or sketched, by hand, on the
surface of the glass with a resinous varnish, or with some of the substances
hereinbefore mentioned as a vehicle for the ink, and then while the design so applied
to the glass is sufficiently moist or sticky, the fluoride, or mixture of fluorides in a
finely powdered condition is dusted over the glass, when it will adhere to the sticky
portions of the surface
Still another method of applying the fluorides to the glass has the advantage of
dispensing with the use of the sticky vehicle, and of distributing the fluoride more
evenly over the surface of the glass. As the fluorides of the alkalies are soluble in
water, an aqueous solution may be used, which if desired can be thickened by the
addition of a very small quantity of mucilage of glycerine-Such solution may be
applied with a pen, brush or stencil-The surface to which it is applied should
then be warmed so as to evaporate the water, when a deposit of solid Huoride will
be found attached to the glass-This deposit being in the form of minute crystals,
when it is afterwards exposed to the requisite degree of heat to produce the
required reaction, the water which is enclosed between the crystals is driven off,
and the deposited salts are apt to fall away from the glass: An addition of

page_text: mucilage to the solution does not entirely obviate this difficulty, and hence it is
better, as soon as the drawing on the glass is sufficiently dry, to cover the
decorated surface with a very thin film of resinous varnish, by which the difficulty
is obviated.
By means of an aqueous solution as just described, fluoride of ammonium may
be used in my process, but it cannot be used mixed with resinous vehicle, because
it volatalizes at a temperature requisite to burn away the varnish: but when the
varnish is laid as a thin film over the deposited fluoride of ammonium this difficulty
does not interfere with its action
Fluoride of ammonium does not produce as great a degree of opacity on the
glass in the etching, as do the fluorides of the fixed alkalies and this fact may be
taken advantage of to produce artistic effect in fine work; different degrees of
opacity being produced in different portions of the same etching, by a skillful
application to some parts of the design a solution of fluoride of ammonium, to
other parts a solution of the fluorides of the fixed alkalies, and to other parts
a mixture of the fluorides of the fixed alkalies and of the alkaline earths mixed
with oil or other vehicle which will not require the same degree of heat to remove
it as varnish does A variation of effect may also be produced by using a different
proportion of the fluoride in making the solution or ink to be applied to different
portions of the work
In making these mixtures and solutions of fluorides with a vehicle or with a
menstruum, I have not given any proportions, as that will depend on the degree
of opacity desired to be produced on the glass. For example, in making an
aqueous solution it may be saturated or not as may be preferred. The fluorides
may also be mixed together, as fluoride of the fixed alkalies, with the fluorides of
the alkaline earths or with the fluoride of ammonium.
As the different fluorides produce different degrees of opacity in the finished
work my process affords the opportunity of producing effects which cannot be
obtained by the ordinary stop off method of etching with liquid hydrofluoric acid
In this connection it may be well to notice that the degree of heat applied in
the subsequent part of my process has an effect on the opacity of the etching, and
that this also varies according to the different fluorides employed, as well as with
the different mixtures of fluorides For example when the fluorides of the mixed
alkalies are employed, the, opacity produced passes away if the final heat is
continued for a longer time than ordinary: and this too varies with the amount
of silica contained in the glass, in which respect different kinds and makes of glass
vary considerably-It is therefore impossible to give any definite rule to govern
the amount or proportions of fluoride to be used to produce any given effect,
but a little care, and experience on the part of the workman will enable him
to utilize these variations of temperature, ingredients and proportions with
admirable effect.
A very pretty effect may be produced in the etching of glassware by my
process, by the use of threads or reticulated thread fabrics such as lace blonde
and similar articles which bave sufficient interstices between the threads to
produce a distinct pattern on the glass. For this purpose the lace or other materials
should be made of vegetable fibre, or of silk; other animal threads or hair being
unsuitable for the purpose. The threads or lace to be so used should be previously
washed in order to remove any foreign matter which might discolor the article to
be ornamented-If the threads or lace be made of cotton, they may if preferred
he first treated with nitric and sulphuric acids, and then washed, in the well known
method of converting cotton into dinitrocelluloid, the advantage of which is that
the threads thereby acquire a sharper outline and become more readily combustible,
and after combustion leave little or no ash-Linen fabrics may be used, but they
do not yield as good a result as silk or cotton. The threads of which the lace is
composed should not be tightly twisted, and should be of as uniform thickness as
possible and the finer the threads the better the result-Wide meshed lace is
preferable to that in which the interstices are smaller

page_text: -
The threads, or lace, previously treated as above described, are then immersed
in an aqueous solution of some of the fluorides before mentioned, or a mixture of
them, or in a fluoride ink prepared as has been stated, and after becoming
thoroughly impregnated therewith, the threads or lace are dried, and are then ready
for application to the glass. For this purpose the surface of the glass or that
part of it which is to be ornamented, with a thin film of some transparent and
quick drying varnish. The threads (if separate threads are used) or the lace fabric,
impregnated as before described, is then carefully applied to, and pressed upon the
varnished surface care being taken that each thread, and every part of the fabric
is closely adherent to the surface of the article-It is then ready to receive the
subsequent treatment.
I will now proceed to describe the method of preparing and applying transfer
pictures or designs for etching by my process
The selection of the basis of the sheet on which the transfer picture or design
is to be produced, will depend on whether it is to be removed from the glass before
or after the final process of etching. If it is to be removed before the final process
then the best way to do it is by wetting the transfer sheet, in which case a thin
paper is used, as the foundation of the picture. The paper should either be unsized
or have very little sizing in it. It is first covered with a slight coating of some
mucilage which is soluble in water. When the mucilage is dry a thin film of
collodion (etherial solution of pyroxylin) or of resin dissolved in ether, and when
this also is dry the picture or design is printed or drawn on the collodion or
resinous surface. The object of using a coating of soluble mucilage first and then
of collodion or resin is that the paper may be removed by water leaving the film
of collodion or resin with the design thereon attached to the glass, and that the
coating of collodion or resin may be removed by the subsequent application of heat,
so as to leave only the design in fluoride attached to the Glass.
As it is a delicate and rather difficult operation to remove the paper basis from
the glass, without disturbing the design, a basis may be used of some substance
which can be burned away without injury to the design underneath it, ordinary
paper in burning will curl and shrivel while still partially adherent to the collodion
or resinous film, and is very apt in so doing to injure the design, but there is a
description of paper known as "Japanese fibre paper" which is very thin and yet
sufficiently strong to receive the design, and which may be used without any
previous preparation, unless the fibres are too open, in which case it should receive
a thin coating of collodion or similar substance which will give it a sufficiently
smooth and unbroken surface to receive the design drawn or painted thereon with
fluoride, fat, starch, mucilage or gelatine may be used instead of the collodion for
this purpose, but if starch mucilage or gelatine are used, the coating should be very
thin, as they are apt to form so thick a cuticle as to form blisters when the volatile
portions of the varnish used to apply the picture are evaporated by the heat.
mixture of collodion and resin I have found serviceable for this purpose, as it
renders the paper tougher, and is dissipated by the heat without injury to the
design.
A
Collodion itself forms a good basis for the transfer picture, but in order to bear
handling, so that the transfer pictures may be sold as articles of manufacture, it
should be spread upon some thin fibrous vegetable tissue, such as paper made of
very fine cotton fibre or gauze or fine blonde.
Sheets may also be made from any finely reticulated fibrous substance of cotton
or silk, the interstices being first closed with varnish starch gelatine or fatty
matter; which will give a sinooth surface but which will be readily evaporated
melted or charred by heat.
In order to cover sheets of Japanese fibre paper or other vegetable silken textile
fabric with a thin film of collodion or of a mixture of collodion with resinous
substances dissolved in ether, such sheets should be stretched on a frame and the
collodion or collodion mixture be applied with a sponge. This must be done
quickly because the sheet softens on application of the etherial solution. A quicker

page_text: method is to place the sheet smoothly on a pane of glass and apply the collodion &
with a sponge or brush after the ether has evaporated the sheet is removed from
the pane of glass by immersion in water for about ten minutes more or less. The
sheet of fibre paper thus coated, after being dried is ready to receive the desired
design. Sheets of collodion without the paper basis may be made in like manner
on a sheet of glass and separated therefrom by wetting, they are better if the
collodion be mixed with some resinous substance. Sheets made of a solution of
resin in ether may also be similarly prepared: but these and the collodion sheets
require a longer immersion in water to separate them from the glass than when
they have a basis of paper.
On the sheet thus prepared the desired design or picture may be sketched
printed or stamped with fluoride ink prepared as before described or with an
aqueous solution of the fluoride or fluorides, thickened if necessary to the desired
consistency as already stated.
After the design has been produced in fluoride ink or solution on the prepared
transfer paper, and when it is thoroughly dry, it should receive a protecting coat,
the character of which will depend upon the character of ink used. If the vehicle
used in making the ink is a resinous or fatty substance the picture should be coated
with a thin film of collodion, varnish, mucilage or starch. If the drawing was made
with a solution of a fluoride salt the coating should be a thin film of a resinous
solution. Such coating is not however always necessary.
Care should be taken to
make all the films or coatings of collodion or resinous substance whether above or
below the design or picture, as thin as possible, so as to prevent the derangement
of the particles of fluoride which compose the design, by the evaporation or charring
of those substances.
Transfer pictures patterns or designs thus prepared are applied to the surface of
the glass to be etched, in the following manner.
The glass surface to receive the transfer picture should first be made thoroughly
clean and dry; then a thin coating of some quick drying varnish is applied either
to the glass or to the transfer picture, and the picture is laid face down in proper
position on the glass surface, and pressed firmly down thereon, so as to prevent the
interposition of bubbles of air, and to secure a perfect contact and adhesion between
the two surfaces. If the transfer picture had received a coating of varnish which
had become hard before the transfer picture is used, both the picture and glass
should be varnished before the picture
laid on.
If the transfer picture has been made on a basis of paper or other material with
a film of mucilage interposed between it and the collodion or resinous film on
which the picture is made, the glass is then immersed in water for a sufficient time
(ten minutes more or less) to cause the mucilage to dissolve when the paper will
separate from the base of collodion or resinous substance, and will float off leaving
the design protected by the collodion or resenous substance adhering to the glass.
The glass is then carefully and thoroughly dried, and is then ready for the next
stage of the process.
I will now proceed to describe the final step in my process, by which the deposit
of solid fluorine on the glass, made in any of the methods herein before described is
caused to act upon the glass so as to produce the desired etching. This effect is
produced by causing a reaction to take place between the fluorine in the fluorides
and the silica in the glass, which in combining pass off as a volatile compound
leaving the glass in the condition known as etched.
But before this reaction commences, the fluorides must be separated from the
vehicle with which they were mixed and brought into intimate contact with the
surface of the glass and the vehicle itself removed out of the way. Both of these
effects may be produced by the action of heat in a suitable furnace, or the first
effect, (removal of the vehicle) may be produced by furnace heat, and the latter by
the combined action of heat and sulphuric acid.
I will first describe the operation by the use of furnace heat alone.
The glass article with the design printed sketched or applied thereto either by

page_text: printing or sketching with fluoride ink or with fluoride solution, or by dusting
comminuted fluoride on the design previously applied in varnish, or by means of
impregnated lace fabric or by the use of transfer pictures or any other known way,
is placed in a suitable oven or furnace which is only slightly warm: the heat of
the furnace is then gradually raised to about 250° Farenheit. The furnace is kept
at that temperature until the turpentine ether and volatile substances used in the
process have been evaporated: this may take an hour or less according to the
quantity of volatile matter employed. The heat of the furnace is then gradually
raised to 500° or 600° Fahrenheit until the more solid chiefly carbonaceous matter
of the vehicle or transfer pictures, or lace fabrics is thoroughly charred and has
disappeared leaving only the film of fluoride on the surface of the glass. If any
small particles of charred matter remain they will ordinarily do no harm.
At this stage of the process any change or correction of the design on the surface
of the glass may be made, as no etching has yet taken place.
The heat of the furnace is then still further raised to about 750° Fahrenheit,
until the article of glass shows of a dull red heat, which is sufficient to produce the
necessary reaction between the fluorine and the silica of the glass. Care must be
taken that the heat be not raised so high, or continued so long, as to melt the
glass, or soften it so much as to cause it to become misshapen. The length of time
during which the maximum temperature is maintained need be only a few minutes:
another reason for care in this regard is that the opacity produced by the fluorides
of the fixed alkalies, passes off and the etched surface assumes a blistered and
frozen appearance if the heat be too great or too long continued. Experience will
Boon enable a skilful workman to discontinue when the desirable maximum of heat
has been attained, and when to begin to reduce it. The glass article should then
be cooled slowly.
The alternative method of producing the necessary reaction between the fluoride
deposited on the glass and the silica in the glass is as follows:-
When the degree of heat sufficient to volatalize the lighter ingredients used in
applying the fluoride to the glass and the further degree of heat necessary to char
and consume the more solid matters has been reached and continued long enough
to remove those substances leaving only the deposited fluoride on the surface of
the glass, instead of raising the heat sufficiently to produce the reaction before
referred to, the article of glass in that condition is then exposed in the same, or
some other furnace to an atmosphere of hot vaporized sulphuric acid. The action
of this hot vapour on the fluoride deposited on the surface of the glass is such as to
create the necessary reaction to produce the etching effect.
The sulphuric acid may be vaporized in the same furnace in which the glass has
been previously heated, and the temperature needs not to be raised above that
necessary to produce the vaporization of the acid, say about 620° to 650° Fahrenheit.
If preferred, however the glass article may be removed from the first furnace to a
special furnace in which the sulphuric acid is vaporized, or the hot vapours of
sulphuric acid may be conducted into the furnace in which the glass receives its
first heating.
°
The advantage of using the hot vapor of sulphuric acid, to produce the reaction
referred to, is that it does not require the glass to be exposed to as high degree of
heat, which is an important consideration in cases where, owing to the thinness of
the glass, or for other causes it is not desirable to subject it to a temperature of
750° Fahrenheit or thereabouts. It does not however produce as great a degree of
opacity in the glass as when the reaction is produced by the agency of a high heat
without the use of the acid vapor.
Having now described and particularized the nature of my said invention in
such manner that others will be enabled to carry my improvements into effect I
would have it understood that I do not confine myself to the exact details
described, but I claim-First: The process substantially as herein before described
of etching glass, by applying to its surface the salts of fluorine, such as the
Aluorides of the fixed alkalies, the fluoride of the alkaline earths or fluoride of

page_text: ammonium by means of a suitable menstruum, or by means of a suitable vehicle
either mixed with the fluoride or applied to the glass separately, and then
exposing the same to the action of heat sufficient to produce a decomposing
reaction between the fluorine so applied and the silica of the glass.
Second: The process substantially as herein before described of etching glass, by
painting, printing on or otherwise applying to its surface a comminuted alkaline
fluoride or mixture of comminuted alkaline fluorides with Venice turpentine or
other suitable vehicle, exposing the glass-ware thus prepared to a degree of heat in
a suitable oven or furnace sufficient first to evaporate the volatile portions of the
vehicle, then to a higher degree of heat sufficient to char or burn away the more
solid constituents of the vehicle, and lastly to a still higher degree of heat to
produce a chemical reaction between the silica of the glass and the fluorine so
applied to it.
Third: The process of etching glass substantially as hereinbefore described, by
the application to its surface, of the salts of fluorine such as the fluorides of the
fixed alkalies, the fluorides of the alkaline earths, or fluoride of ammonium by
mixing the same, or compounds thereof with a suitable vehicle, or dissolving them
in a suitable menstruum, and then impregnating threads or reticulated textile
fabrics with such mixture or solution, applying such impregnated fabric to the
surface to be etched; and then exposing the article so prepared to suitable heat
in an oven
or furnace to remove the volatile and carbonaceous matter, and
finally produce a reaction between the fluoride or fluorides and the silica of the
glass.
Fourth: In combination with the various processes of applying fluorides in a
solid condition to the surface of glassware, and removing the volatile and
carbonaceous ingredients of the vehicle or menstruum used to apply the same by
means of heat in a furnace, the further process of producing a reaction between
the deposited fluoride or fluorides and the silica of the glassware by means of hot
vapor of sulphuric acid, for the purpose of etching glass substantially as herein-
before described.
Fifth The solution in water or other suitable menstruum of a comminuted
Bolid alkaline fluoride, or mixture of alkaline fluorides, as an ink for writing
printing or sketching on glassware, preparatory to its exposure to heat or to the
hot vapor of sulphuric acid, for the purpose of etching the surface of such glassware
substantially as described.
Sixth: The mixture of a comminuted solid fluoride, or fluorides, with a suitable
fluid or semi fluid vehicle, as an ink for writing, printing, or sketching on the
surface of glassware, preparatory to its exposure to heat or to the hot vapor of
sulphuric acid, for the purpose of etching the surface of such glassware, substan-
tially as described.
Seventh The method of applying the salts of fluorine such as fluorides of the
fixed alkalies and of alkaline earths, or mixture thereof to the surface of glass, in
designs or patterns to be etched thereon, by means of transfer pictures or designs
printed or drawn on prepared sheets of thin paper or textile fabric or films of
collodion, or of collodion and resinous matter or equivalent substances substantially
as hereinbefore described.
Eighth The method of preparing transfer pictures or designs for depositing on
the surface of glassware to be etched, a thin film of the fluoride of sodium or other
fixed alkali, or of the fluorides of alkaline earths or mixtures thereof, by drawing,
painting, or printing on a sheet of fibrous material, or of collodion or other
equivalent easily combustible fabric, the desired picture or design, with a solution
of such fluoride or fluorides in a suitable menstruum, or with an ink containing
the same in admixture, and protecting the surface of such design or picture
with a coating of collodion or resinous varnish or its equivalent, substantially as
described.
Ninth As a new article of manufacture, sheets of thin combustible reticulated,
woven or fibrous material (for the purposes herein set forth) the interstices of

page_text: which are filled with a film of collodion, or equivalent combustible, fusible or
volatile substance, on which are printed, painted or otherwise impressed, designs
for etching glass with an ink containing in admixture or solution the fluoride of
a fixed alkali, or of alkaline earth or other similar fluorides, and with or without
a protecting film of collodion, resinous varnish or the equivalent thereof, substan-
tially as described.
Tenth The process hereinbefore described of etching glass by the application
to its surface of the fluorides of the fixed alkalies or of alkaline earths, or of
ammonium or equivalent fluorides and producing a reaction between the silica of
the glass and such fluoride or fluorides, substantially in the manner described.
In Witness whereof I the said John Thomson King have hereunto set my
hand and seal this second day of November in the year of our Lord One
thousand eight hundred and eighty three.
JAMES JOHNSON
Patent Office
Witness
4 Clayton Square
Liverpool
J. T. KING (L.S.)