Civil Engineering Reference
In-Depth Information
The paint trade has changed a great deal over the last 100 years. During the nineteenth
century painters prepared the pigments themselves from the raw materials. Even as late
as the 1960s most painters mixed paints themselves, although ready-mixed paints had
been on the market since the end of the nineteenth century. During the last 30 years
everything has been industrialized, including the application of paint, particularly for win-
dows, doors and outside panelling.
Conditions for painting
Painting should be done during a dry period when the surface is dry, prefer-
ably in the summer. The temperature does not matter too much, as long as it
is above freezing. This is particularly important for linseed oil paints.
Painting carried out during the autumn often seems to last longer than paint-
ing done during the summer, probably because the paint has dried more
slowly. In hot sunny weather paint can easily crumple, because of a tension
between the different coats.
It is important to choose the right paint for the right surface. Wood, for exam-
ple, is an organic material which is always moving, swelling in damp weather,
drying out and shrinking in dry weather, and these qualities should be taken into
account.
The main ingredients of paint
Binders
Binders must be able to dry out without losing their binding power. Many dif-
ferent binders have been used througout history, including materials such as
blood, sour milk and urine. According to a representative of the Norwegian cus-
todian of national monuments, Jon Braenne, many of these 'improbable' paints
gave 'amazingly good results' (Drange, 1980). Linseed oil and protein glue have
been amongst the most popular, with a long tradition, and have been in contin-
uous use up to the end of the 1950s. At this time synthetic resins arrived on the
scene, replacing the old faithfuls. Different types of binder vary a great deal in
terms of opacity, lustre, spreading rates and durability.
Solvents
Solvents are used to thin out thick paint mixtures and vaporize from the surface
after painting. For certain types of paint, the binder is enough to dissolve the
paint into a satisfactory consistency, as in the case of cold pressed linseed oil,
