AN IMPROVED PROCESS OF ORNAMENTING GLASSWARE BY THE PRODUCTION OF A METALLIZED CRACKLE THEREON
Year: 1878

page_text: LETTERS PATENT to Alexander Melville Clark, of Chancery Lane, in the
County of Middlesex, Patent Agent, for the Invention of "AN IMPROVED
PROCESS OF ORNAMENTING GLASSWARE BY THE PRODUCTION OF A METALLIZED
CRACKLE THEREON." A communication from abroad by Messieurs Monot,
nèrè et fils and Stumpf. of Paris, France.
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark at
the Office of the Commissioners of Patents on the 29th November 1878.
ALEXANDER MELville Clark, of Chancery Lane, in the County of Middlesex,
Patent Agent. AN IMPROVED PROCESS OF ORNAMENTING GLASS WARE BY THE
PRODUCTION OF A METALLIZED CRACKLE THEREON." [A communication from
abroad by Messieurs Monot, père et fils, and Stumpf, of Paris, France.]
"
This Invention relates to the production on all kinds of crystal and glassware of
what is herein termed "metallized crackle." To produce the "crackle a layer of
glass containing an easily reducible metallic composition is enclosed between two
other layers of glass of any suitable color, and while the glass is still hot and but
partly blown it is plunged into cold water, withdrawn, and blown or moulded of
the form desired. The outside layer of glass is crackled by contact with the cold
water, and the intermediate layer is thus exposed wherever the cracks or veins have
been produced. The article when finished, and while it is still hot, is placed in a
reducing medium or exposed to the action of a reducing gas, which acting upon the
intermediate layer laid bare by the cracks or veins, metallizes them, and produces a
"metallized crackle" never before known.
•
The Invention also comprises all the various modes of applying the process, and
the combination of this and other processes. For example, a double, triple, quad-
ruple, or multiple "metallic crackle" may be produced by forining the article of
four, five, six, or a greater number of layers of glass successively crackled and
reduced as before described.

page_text: A modification of the process consists in producing the crackle by means of
powdered or granular glass, as in making frosted glass, the veins being afterwards
metallized as above described; or the ground only or grain may be metallized, and
not the veins or crackle; or both the ground and the veining may be metallized,
but with different metals.
Further, by the aid of masks or protecting surfaces suitably applied, portions
only of the glassware may be crackled, the crackle thus forming patterns or
designs.
Lastly, vases or other articles having a metallized crackle applied as described
may be further ornamented in any suitable manner, and particularly by metallizing
their interior surface, by a process described in another application for Letters Patent
of even date herewith..
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Alexander Melville Clark in the Great Seal Patent Office on the
29th May 1879.
ALEXANDER MELVILLE CLARK, of Chancery Lane, in the County of Middlesex,
Patent Agent. "AN IMPROVED PROCESS OF ORNAMENTING GLASS WARE BY THE
PRODUCTION OF A METALLIZED CRACKLE THEREON." A communication from
abroad by Messieurs Monot, père et fils, and Stumpf, of Paris, France.
"
This Invention relates to the production on articles of crystal and other glass
of what is herein termed "metallized crackle." To produce the "crackle a layer
of glass containing an easily reducible metallic compound (oxide of copper for
instance) is first imprisoned between two other layers of glass of any suitable color;
this being done, and while the glass is still at a good heat and but partly blown, it
is plunged into cold water, withdrawn, and then moulded or blown to the desired
form. The first or outside layer of glass is cracked or "crackled " by contact with
the cold water, and when the article is still further expanded in moulding or blowing
it to the desired form, the intermediate layer becomes exposed wherever the cracks
or fissures have been produced. The article when finished, and while it is still hot,
is placed in a reducing medium or exposed to the action of a reducing gas, which
acting upon the intermediate layer laid bare by the cracks or fissures metallizes the
same, producing a veined appearance termed a "metallized crackle never before
produced. The outside or protective layer of glass may be of any suitable compo-
sition, and may or may not itself contain another metallic compound, which being
reduced at the same time as that contained in the underneath layer exposed at the
cracks, will give the ground a color different to that of the veins. The reducing
gas varies according to the metallic compound to be reduced, and may be hydrogen,
carbonic oxide, or carburetted hydrogen, as the case may be. For example, to reduce
oxide of copper, hydrogen would be used.
"
The Invention comprises all the various modes of applying the process, and the
combination of this with other processes. For example, a double, triple, or multiple

page_text: "metallic crackle" may be produced by forming the article of four, five, six, or
more layers of glass, which are successively "crackled" and the metallic compound
they contain reduced as before described. These layers may be of different colors,
and contain metallic compounds, producing by their reduction veins of different
tints.
A modification of this process consists in producing the "crackle" by means of
granulated glass, as in making frosted glass, the veins being afterwards metallized
as above described. Or the ground only may be metallized, and not the veins or
crackle; or both the ground and the veining may be metallized, but with different
metals, as before mentioned. Further, by the aid of protecting masks of some
infusible material, such as clay, suitably applied, portions only of the glass ware may
be "crackled," the crackle being thus limited to certain patterns or designs.
Lastly, vases or other articles having a metallized crackle produced as described
may be further ornamented in any suitable manner, and particularly by metallizing
their interior surface by a process described in the Specification of Letters Patent
of even date herewith, No. 4880.
Having described the nature of the 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 process, substantially as herein specified, of producing upon crystal and other
glass ware the novel effect herein designated "metallized crackle."
In witness whereof, I, the said Alexander Melville Clark, have hereunto set
my hand and seal, this Twenty eighth day of May, in the year of our Lord
One thousand eight hundred and seventy nine.
A. M. CLARK. (L.S.)