Civil Engineering Reference
In-Depth Information
only to the car (Weissenfeld, 1985). Binders and other additives also affect the
environmental profile in manufacture, and there is a tendency towards plant
products coming out best. It is mainly the organic solvents that cause problems
in the paint trade, but various additives in modern synthetic resin paints are also
problematic.
Inside buildings, the materials covering the surfaces have a large impact
because they extend over such large areas. Emissions often continue several
months after the work is completed. A whole series of different volatile sub-
stances can be emitted from certain synthetic resin products, their source usual-
ly being unreacted monomers and additives. As a general rule, the thicker the
layer of paint, the longer the time taken for the paint to complete its emissions.
In many cases, there are gases which have a very strong irritant effect on the res-
piratory system. Certain surface treatments can also be quite heavily electrostat-
ically charged, which can make cleaning more difficult and increase the electro-
static charge of the inhabitants (see Table 15.1).
Materials that have had surface treatments are not easily recycled. Exceptions
include treatments such as vegetable waxes or oils. The same principle applies to
the potential for energy recycling and the problem of waste. Painted materials
often have to be deposited at special tips. As waste, the pigments have the great-
est impact, as they can contain heavy metals.
Paints in history
Surface decoration has been popular throughout the ages. Stone Age cave painters used
paint based on binders of fat, blood and beeswax, using chalk, soot and different earth
colours as pigments. Natural pigments were also used for Egyptian fresco paintings about
5000 years ago. Old Hebrew writings describe how casein was stored in the form of curd
until the annual visit of the painter during the autumn; at harvest festivals, everything
should be newly painted. In Pompeii, paint mixtures of chalk, soap, wax, pigment and
water have been found.
It is generally assumed that timber buildings remained untreated up to the late Middle
Ages, but as wealthier citizens began to have panelling installed in their houses at the end
of the seventeenth century, surface treatments became more usual. The first coloured tar
paintings came into being at this time. The object of painting was to make timber buildings
look like stone and brick. The pigments were expensive, with the exception of the earth
pigments English Red and Ochre, which after a while dominated the houses of craftsmen,
farmers and prosperous citizens.
Around 1700, linseed oil came into use. During the nineteenth century many old and
new pigments could be produced chemically. Painting a house became cheaper, and
colours other than red and yellow, such as zinc white, became available to everybody. At
this time, everyone had untreated floors, apart from scouring them with sand. Floor paint-
ing began around 1820. From the middle of the twentieth century, very rapid develop-
ments led to latex paint, synthetic oil paints and alloyed paints, based on raw materials of
fossil origin.
