DOI Page / Citation link:
https://doi.org/10.11588/diglit.7186#0021
Introduction.
7
elastic force sufficient not only to crack the piece that contains it, but even to
split it to fragments. This is the reason why Boni adheres to the system
of applying the paste in small pieces to the moulds, and leaving spaces at
intervals; thus endeavouring to obtain an equal, slow, and thorough expulsion
of the water from the modelled paste. For this reason, having studied the
proportions of the disjunctive materials, he finds it needful to protect his works
from the direct and too forcible action of the wind, and to watch that they be
always accessible to the steady and beneficial influence of heat and light.
Thus the pieces withdrawn from the moulds are dried in the calm open
air, if small at the stove, if bulky at the furnace. To effect this, a large board
is set up on an inclined plane, under which is fixed a vessel of sheet-iron to
carry off the heated air and the products of that combustion which is regulated
in the stove.
By these contrivances the large pieces are almost always preserved from
cracking, because the paste, being of uniform substance throughout every atom of
it, submits to the same conditions, and undergoes equally the shrinking process,
the upper portions gravitating infallibly though lightly on the lower.
So soon as the moulded objects have attained the due degree of dryness,
they are polished by hand and consigned to the furnace, where the burning is
effected by means of combustibles calculated to emit flame.
The fireplace is fitted with a roof on which are arranged the pieces to be
burnt ; and the flames ascend amongst them by means of many apertures
pierced in the roof itself; wherefore combustibles which burn with a long-
sustained flame are to be chosen even though inferior in point of heat. In the
Milanese workshops wood is the fuel preferred on economic grounds.
Yet all this care in drying and firing would fail to ensure solidity to the
work, if the conditions essential for obtaining perfect homogeneity and com-
pactness of the earths were not first observed. In ceramic pastes two kinds of
homogeneity must be aimed at: one of parts, the other of masses. The first
consists in equality of nature, uniformity of volume, invariableness of density,
7
elastic force sufficient not only to crack the piece that contains it, but even to
split it to fragments. This is the reason why Boni adheres to the system
of applying the paste in small pieces to the moulds, and leaving spaces at
intervals; thus endeavouring to obtain an equal, slow, and thorough expulsion
of the water from the modelled paste. For this reason, having studied the
proportions of the disjunctive materials, he finds it needful to protect his works
from the direct and too forcible action of the wind, and to watch that they be
always accessible to the steady and beneficial influence of heat and light.
Thus the pieces withdrawn from the moulds are dried in the calm open
air, if small at the stove, if bulky at the furnace. To effect this, a large board
is set up on an inclined plane, under which is fixed a vessel of sheet-iron to
carry off the heated air and the products of that combustion which is regulated
in the stove.
By these contrivances the large pieces are almost always preserved from
cracking, because the paste, being of uniform substance throughout every atom of
it, submits to the same conditions, and undergoes equally the shrinking process,
the upper portions gravitating infallibly though lightly on the lower.
So soon as the moulded objects have attained the due degree of dryness,
they are polished by hand and consigned to the furnace, where the burning is
effected by means of combustibles calculated to emit flame.
The fireplace is fitted with a roof on which are arranged the pieces to be
burnt ; and the flames ascend amongst them by means of many apertures
pierced in the roof itself; wherefore combustibles which burn with a long-
sustained flame are to be chosen even though inferior in point of heat. In the
Milanese workshops wood is the fuel preferred on economic grounds.
Yet all this care in drying and firing would fail to ensure solidity to the
work, if the conditions essential for obtaining perfect homogeneity and com-
pactness of the earths were not first observed. In ceramic pastes two kinds of
homogeneity must be aimed at: one of parts, the other of masses. The first
consists in equality of nature, uniformity of volume, invariableness of density,