Agriculture Reference
In-Depth Information
Figure 136
Trimming the excess
bead of mortar from the
facework. (Courtesy of
Gerald Edkins)
For completed arches, accepted best practice was to pour a stronger hydraulic
lime:silver sand grout into 'joggle-joints' (cavities cut, or filed, into the opposing
beds of voussoirs) once the arch was 'turned', to increase its strength. Later in
the period Portland cement, that was much weaker than its modern counter-
part, was increasingly preferred for grout due its to speed of set and strength.
Grouting with Portland cement was also sometimes employed at the rear of
gauged brickwork to be carved
in situ
, as Walker (1885, 63-4) indicates:
If the work has to be carved deeply, it is best to build it all 'headers', and 'grout'
it in solidly at back with Portland cement, that the bricks may not break up or get
disturbed under the chisel of the carver.
Generally, where strength of the bedding matrix was important (such as for
door reveals, on projecting oriels, or
in situ
carved enrichments), a different
mortar was necessary. The historic hot or cold cements could be used, indeed
they were still in use in France during the nineteenth century, as Burnell
(1874, 94) states:
The French plumbers unite the glazed pottery tubes they employ for the distri-
bution of water, with a hot cement made of resin, wax, and lime; or with a cold
cement composed of quick lime, cheese, milk, and the white of eggs.
The use of either type of 'cement' was, however, fast declining instead, as
Walker (1885, 64) explains:
A composition of whitening [whiting] and patent knotting is more frequently
used than lime-putty for bedding or setting work intended to be carved, and for
ornamental key-blocks made up of two or more bricks. It will be found most con-
venient to put such keys or blocks together in the cutting-shed, and take them
upon the building to be set as one piece of work. These remarks apply equally
well to the niche hood in every particular.
