IMPROVE- MENTS IN THE GLAZING OF EARTHENWARE.
Year: 1879

page_text: LETTERS PATENT to William Affleck Gray, Alexander Gray, and William Gray,
all of Portobello and Musselburgh, in the County of Midlothian, North Britain,
Stoneware and Earthenware Manufacturers, for the Invention of "IMPROVE-
MENTS IN THE GLAZING OF EARTHENWARE.
"
aled the 22nd July 1879, and dated the 15th March 1879.
PROVISIONAL SPECIFICATION left by the said William Affleck Gray,
Alexander Gray, and William Gray at the Office of the Commissioners of
Patents on the 15th March 1879.
.
WILLIAM AFFLECK GRAY, ALEXANDER GRAY, and WILLIAM GRAY, all of
Portobello and Musselburgh, in the County of Midlothian, North Britain, Stone-
ware and Earthenware Manufacturers. "IMPROVEMENTS IN THE GLAZING OF
EARTHENWARE."
The said Invention relates to the glazing of common white earthenware, such for
instance as is used for the making of jam-pots and the like. The body of the
articles to be glazed is composed of ball clay, china clay, ground flint, and Cornish
stone. The said articles to be glazed thus composed are treated as follows:-
The first firing or biscuiting is dispensed with, and the articles in their green dry
state are coated with a glaze composed of Cornish stone about 28 parts; Paris
white or whiting, about 12 parts; ball clay, about 6 parts; ground flint, about +
parts; and (if desired to give a blueish shade) a small quantity of cobalt. When
so coated the articles are fired in the kiln, and thus the baking and glazing are both
effected by one firing, instead of by two as at present, and economy of time and
fuel results, and the articles are harder and stronger than those manufactured and
glazed in the ordinary way, and are more suitable for the reception of acid or
substances containing acid.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said William Affleck Gray, Alexander Gray, and William Gray in the
Great Seal Patent Office on the 12th September 1879.
WILLIAM AFFLECK GRAY, ALEXANDER GRAY, and WILLIAM GRAY, all of
Portobello and Musselburgh, in the County of Midlothian, North Britain, Stone-
ware and Earthenware Manufacturers. "IMPROVEMENTS IN THE GLAZING OF
EARTHENWARE."
The said Invention relates to the glazing of common white earthenware, such for
instance as is used for jam-pots and the like.
The body of the articles to be glazed is or may be composed as follows:—
Blue ball clay
China clay
-
Ground flint-
Cornish stone
.
about 1
part
-
"
1
parts
1
"
part
¾
"
">
The said articles to be glazed thus composed are treated as follows:-The first
firing or biscuiting is dispensed with, and the articles in their green dry state are
coated with a glaze which may be thus composed,-
Cornish 'stone
Paris white or whiting
Ball clay
Ground flint
about 24 parts
12
"
"
4
"
"
4
"
"
If desired, in order to give a blueish shade, a small quantity of cobalt may be
added.
When coated with glaze the articles are fired in the kiln, and thus the baking
and glazing are both effected by one firing instead of by two, as at present, and
economy of time and fuel results, and the articles are rendered harder and stronger
than those manufactured and glazed in the ordinary way, and the said articles are
also more suitable for the reception of acid or substances containing acid.
Having now described and particularly ascertained the nature of our said Inven-
tion, and the system, mode, or manner in or under which the same is or may be
used or practically carried into effect,, we would observe in conclusion that we wish
it to be understood that we do not limit ourselves to the ingredients or proportions
of ingredients of which the body or the glaze is composed, as the same may, be varied
without departing from, the nature of our Invention, but what we consider to be
novel and original and therefore claim as the Invention secured to us by the herein-
before in part recited Letters, Patent is,―
The herein-before described improvements in glazing earthenware, consisting in
applying glaze to earthenware when in a green dry state, and finishing by one
firing.
In witness whereof, I, the said Alexander Gray, have hereunto set my hand
and seal, this Eleventh day of September, in the year of our Lord One
thousand eight hundred and seventy nine