IMPROVEMENTS IN THE TREATMENT OF NATURAL AND ARTIFICIAL STONE, AND IN THE MANUFACTURE OR PRODUCTION OF ARTIFICIAL STONE
Year: 1860

page_text: PROVISIONAL SPECIFICATION left by Barnabas Barrett at the Office
of the Commissioners of Patents, with his Petition, on the 17th
November 1860.
I, BARNABAS BARRETT, of St. Giles' Road, in the City of Norwich, Sculptor,
do hereby declare the nature of the said Invention for "IMPROVEMENTS IN THE
TREATMENT OF NATURAL AND ARTIFICIAL STONE, AND IN THE MANUFACTURE OR
PRODUCTION OF ARTIFICIAL STONE," to be as follows:-
This Invention relates to a system or mode of hardening, coloring, and
enamelling natural and artificial stone, and also to a process or processes for
manufacturing artificial stone.
In treating natural stone the stone to be operated upon should be first
shaped or fashioned to its desired form. When sandstone is to be hardened
and enamelled it is first thoroughly dried in a heated chamber, and is then
immersed in a hardening mixture composed of, say, 30 lbs. of purified pearlash,
15lbs. of saltpetre, 1lb. of borax, and 1½ ozs. of arsenic, melted together, and
used in a lukewarm state. The stone is now to be dried again, and then
placed in a kiln and subjected to a red heat. After the stone has cooled again
it may, if desired, be subjected to an enamelling mixture, consisting of equal
parts of oxide of lead, ground flint and glass, and ground clay, the whole to be
reduced to a powder, and mixed with water to about the consistency of cream;
the mixture being either applied with a brush or the stone immersed therein,
after which the stone is subjected to a red heat in a kiln. For hardening and
enamelling limestone the stone is first thoroughly dried, as above described,
and is hardened, and receives a good surface by being subjected to a hardening

page_text: mixture, consisting of equal parts of spirits of turpentine and the best copal
varnish; which, when in a lukewarm state, may be applied with a brush.
This mixture is equally applicable to the indurating of porous stones of all kinds.
In making artificial stone I take, according to one process, say, 60 lbs. of
pulverised stone, 30 lbs. of purified pearlash, 15 lbs. of saltpetre, 1 lb. of borax, 5
lb. of lime, 1 lb. of oxide of lead, 15 lbs. of clay, and 2 lbs. of calcined flint;
the whole to be mixed together, and then pressed into moulds. When dry
the blocks so formed are placed in a kiln and subjected to a red heat, and
when cool will be found to have all the properties of natural stone.
Another process for making artificial stone consists in the admixture of, 1
say, two parts of unslacked lime and three parts of pulverised lime or sand-
stone well mixed together and passed through a fine sieve. To this are added
twelve gallons of water, 12 lbs. of alum, or its equivalent, gallon of beer
grounds, one pint of hydrochloric acid (spirits of salt). If the stone is to be
colored, suitable colors are mixed with the above ingredients, and the whole is
then to be pressed in moulds and treated as before described.
If it be desired to color and enamel natural or artificial stone so as to
imitate black marble, the stone to be treated is coated with a mixture of coal
tar, varnish, spirits of turpentine, and vegetable black, well ground and mixed
together. The stone, thus coated, is heated in a stove for twelve hours, and is
then rubbed with pumicestone, and washed and dried. Another coat of
coal tar, varnish, or black japan is then applied, and the stone is replaced in
the stone again for about 15 or 24 hours, and subjected to from 120 to 200
degrees of heat Fahrenheit. It is then removed, and again well rubbed with
pumicestone, washed clean and polished by hand with rottenstone or putty
powder.
To imitate colored marbles, suitable colors are to be mixed with copal
varnish and spirits of wine, and applied with a brush, and after such applica-
tion the mixture of spirits of turpentine and copal varnish, herein-before
referred to, is to be brushed on, and the stone is then placed in a stove or oven
for 12 hours. After which it is cooled and rubbed with pumicestone. A coat
of copal varnish is now applied, which may be repeated as often as required,
the stone after each application being placed in the oven and subjected to
from 150 to 200 degrees of heat Fahrenheit for 12 hours, after which it is
finally polished by hand, as above described.