IMPROVEMENTS IN THE MANUFACTURE OF BRICKS, TILES, COPINGS, AND OTHER LIKE WARE OF A BLUE OR VITRIFIED NATURE."
Year: 1881

page_text: LETTERS PATENT to Edward Johnson, of the Greengate Brick and Tile Works,
St. Helen's, in the County of Lancaster, for an Invention of "IMPROVEMENTS
IN THE MANUFACTURE OF BRICKS, TILES, COPINGS, AND OTHER LIKE WARE
OF A BLUE OR VITRIFIED NATURE."
PROVISIONAL SPECIFICATION left by the said Edward Johnson at the
Office of the Commissioners of Patents on the 7th July 1881.
EDWARD JOHNSON, of the Greengate Brick and Tile Works, St. Helen's, in
the County of Lancaster. "IMPROVEMENTS IN THE MANUFACTURE OF BRICKS,
TILES, COPINGS, AND OTHER LIKE WARE OF A BLUE OR VITRIFIED NATURE."
Hitherto what are generally termed blue bricks, or Staffordshire blue bricks and
tiles, or other articles of a similar nature, have been manufactured by the admixture
of swart or ferruginous mixture with mine clay or surface clay; or bricks or tiles
made from clay have been dipped in a mixture of this substance in water, or
rolled in or dusted with it in a dry state so as to give a suitable skin of a blue
colour.
I have discovered that copper slag or the refuse from ordinary copper smelting
furnaces answers the same purpose, and also is superior to the ordinary oxide of
iron in imparting a deep blue colour to the bricks or tiles, as the slight trace of
copper contained in the slag in addition to the iron has the effect of dyeing the
bricks and deepening the colour. The silica also that the slag contains partially
vitrifies the brick when burnt, rendering it uniform throughout, and making it of
so refractory a nature as perfectly to withstand the action of any acids or long
exposure to sea water or sewage.
My mode of employing this article is to add a varying proportion of copper slag
to any mine clay or surface clay, thoroughly mixing it with the slag in an ordinary
mortar mill, or pug mill, or other suitable appliance for this purpose. In practice
I find that one fourth copper slag mixed with three fourths clay will give a good
result. The brick or tile afterwards when formed, but before burning, may be
rolled in or dusted with the dry powdered slag, or dipped in an aqueous mixturo
of it to deepen the outside colour.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Edward Johnson in the Great Seal Patent Office on the 7th January
1882.
EDWARD JOHNSON, of the Greengate Brick and Tile Works, St. Helen's, in
the County of Lancaster. "IMPROVEMENTS IN THE MANUFACTURE OF BRICKS,
TILES, COPINGS, AND OTHER LIKE WARE OF A BLUE OR VITRIFIED NATURE."
Hitherto what are generally termed blue bricks, or Staffordshire blue bricks and
tiles, or other articles of a similar nature, have been manufactured by the admixture
of swart or ferruginous mixture with mine clay or surface clay; or bricks or tiles
made from clay have been dipped in a mixture of this substance in water, or
rolled in or dusted with it in a dry state, so as to give a suitable skin of a blue
colour.
I have discovered that copper slag or the refuse from ordinary copper smelting
furnaces answers the same purpose, and also is superior to the ordinary oxide of
iron in imparting a deep blue colour to the bricks or tiles, as the slight trace of
copper contained in the slag in addition to the iron has the effect of dyeing the
bricks and deepening the colour. The silica also that the slag contains partially
vitrifies the brick when burnt, rendering it uniform throughout, and making it of
so refractory a nature as perfectly to withstand the action of any acids or long
exposure to sea water or sewage.
My mode of employing this article is to add a varying proportion of copper slag
to any mine clay or surface clay, thoroughly mixing it with the slag in an ordinary
mortar mill, or pug mill, or other suitable appliance for this purpose. In practice
I find that about one fourth copper slag mixed with about three fourths clay will
give a good result. The brick or tile afterwards when formed, but before burning,
may be rolled in or dusted with the dry powdered slag, or dipped in an aqueous
mixture of it to deepen the outside colour.
Having now described my Invention and the best mode known to me of carrying
it into effect, I wish it to be understood that what I believe to be new and desire
to protect under the herein before in part recited Letters Patent is,-
First. The manufacture of tiles, copings, and other like blue or vitrified ware
from a thorough mixture of comminuted copper slag and mine or surface clay.
Second. In the manufacture of bricks, tiles, copings, or other like ware, coating
the clay block before burning with pulverized copper slag, so as to alter or deepen
the outside colour of the brick or tile on being burnt, substantially as described.
In witness whereof, I, the said Edward Johnson, have hereunto set my
hand and seal, this Sixth day of January, in the year of our Lord One
thousand eight hundred and eighty two.
EDW. JOHNSON. (L.S.)