| The Materials of the Town |
|
The materials which characterize the townscape of
fifteenth-century Florence are the stone of the unplastered
facades and of the paving of the piazzas and streets, the
plaster, the wood of the eaves and of structures such as the
struts of the overhangs, the terracotta of some pavements and
above all of the roofing tiles, the iron in the details of the
facade. The typical stones in Florence were pietra forte and
pietra macigno. Pietra forte is an arenaceous limestone of a
fairly uniform grain and yellowish-brown in color, with
occasional patches of a greyish blue. The quarries for pietra
forte were in the hills south of the city. There were two types
of pietra macigno: pietra serena and pietra bigia, sandstones
composed of quartz, silicates and mica, with shiny flakes. Pietra
serena is a light sky blue in color, pietra bigia, with a finer
grain, is the color of the earth, a tawny grey. The macigno
quarries were in the hills north of the city (Fiesole, Maiano).
Pietra forte is harder than macigno and lasts longer (but
generally this depends on how the stone was cut in the quarry and
how it was used). It has a marble veining which may cause it to
break off (and therefore is dangerous to use in cornices). Pietra
serena lasts well under cover but when exposed to weathering
tends to flake and disintegrate. Pietra forte had given medieval
Florence its character ('all of steel-grey stone', for when fresh
from the quarry the stone has a warm brown color but with time it
blackens and takes on an iron hue) and was still used in the
facades of palaces in the high Renaissance (Medici, Antinori,
Pitti, Strozzi, Gondi).
The renewal of Florentine architecture initiated by Brunelleschi
is also evident in the choice of materials. He introduced the
widespread use of pietra serena and pietra bigia. The former,
easier to work, was used for capitals and corbels and the large
monolithic columns (interiors of S. Lorenzo and S. Spirito,
courtyards of Pal. Strozzi, Gondi), for which pietra forte was
ill suited. In the Ospedale degli Innocenti Brunelleschi
introduced the use of pietra serena in the facade as well.
After Brunelleschi, plaster became the ideal background for an
architectural layout provided by the membering. When rustication
was still used, the intention in any case was to realize a
layout; the case of the facade of Palazzo Rucellai is
paradigmatic, for the rustication does not correspond to the cut
of the individual blocks of stone.
|
