DOI Seite / Zitierlink:
https://doi.org/10.11588/diglit.7186#0022
8
Introduction.
in each constituent of the paste; and is attained by working, by kneading, by
sifting, finally by mixing the ingredients already finely pulverized. The
second, and more important, results from an uniform blending of the dissolved
earths ; so that the inevitable modifications produced by desiccation and
burning may affect alike every portion of the mass, which renders it highly
advisable that, before moulding, the earths be subjected to much kneading with
hands and feet.
A paste, not thoroughly homogeneous, fails to sustain equally in all parts
the influence of heat. Hence neither judicious choice and just balance of in-
gredients, nor washings, grindings, mixings, slow desiccation, will suffice : to
render the paste homogeneous, mastery of molecular forces must be secured.
Homogeneity is a final result brought about by minute processes carried on
through a lengthened period. It is therefore indispensable that vast depots be
formed, where the excavated materials, before being reduced to a paste, may
undergo at leisure atmospheric influences, and where large masses of the damp
paste may remain for some years so as truly to rot, to give scope, that is, to the
daily internal motions of the molecules themselves, before undergoing moulding
or modelling, and being exposed to the action of fire.
On these conditions only can terra-cottas modelled in relief attain, from an
industrial point of view, their perfection.
The way in which terra-cottas were introduced into walls was not unlike
that commonly used for inserting stone, marble, corbels, and jambs of stone. It
is evident that the general skeleton of the wall was first constructed, keeping
some bricks protruding, so that afterwards the casts, figures, heads, cornices,
and such like, might be introduced into the interstices left between brick and
brick out of the redundant material beyond the substance of the wall itself.
Such pieces, if flat or slightly salient, were fixed in simply with lime and plaster ;
at the most, for greater strength, hooks of iron or mere nails were used. Large
blocks were secured in the same way as corbels or stone cornices : they took,
however, the precaution to hollow out by hand such figures as required to be
Introduction.
in each constituent of the paste; and is attained by working, by kneading, by
sifting, finally by mixing the ingredients already finely pulverized. The
second, and more important, results from an uniform blending of the dissolved
earths ; so that the inevitable modifications produced by desiccation and
burning may affect alike every portion of the mass, which renders it highly
advisable that, before moulding, the earths be subjected to much kneading with
hands and feet.
A paste, not thoroughly homogeneous, fails to sustain equally in all parts
the influence of heat. Hence neither judicious choice and just balance of in-
gredients, nor washings, grindings, mixings, slow desiccation, will suffice : to
render the paste homogeneous, mastery of molecular forces must be secured.
Homogeneity is a final result brought about by minute processes carried on
through a lengthened period. It is therefore indispensable that vast depots be
formed, where the excavated materials, before being reduced to a paste, may
undergo at leisure atmospheric influences, and where large masses of the damp
paste may remain for some years so as truly to rot, to give scope, that is, to the
daily internal motions of the molecules themselves, before undergoing moulding
or modelling, and being exposed to the action of fire.
On these conditions only can terra-cottas modelled in relief attain, from an
industrial point of view, their perfection.
The way in which terra-cottas were introduced into walls was not unlike
that commonly used for inserting stone, marble, corbels, and jambs of stone. It
is evident that the general skeleton of the wall was first constructed, keeping
some bricks protruding, so that afterwards the casts, figures, heads, cornices,
and such like, might be introduced into the interstices left between brick and
brick out of the redundant material beyond the substance of the wall itself.
Such pieces, if flat or slightly salient, were fixed in simply with lime and plaster ;
at the most, for greater strength, hooks of iron or mere nails were used. Large
blocks were secured in the same way as corbels or stone cornices : they took,
however, the precaution to hollow out by hand such figures as required to be