dk nkf - Nordisk Konservatorforbund Danmark

Figure 1. The content of solid binder, in this jar of styrenebutadiene
paint from the 1950s, is shown next to the jar.
It is obvious why the binder determines most of the paint’s
characteristics.
durability, appearance, the ease of applying, lowering
costs, avoiding health hazards etc.
In the beginning of the twentieth century, industrially
made paint would typically consist of one pigment,
one or two binders and usually a diluent. By the end
of the twentieth century this list could compromise:
binder, binder surfactant, binder coalescing agent,
one or more pigments, pigment dispersant, pigment
wetting agent, filler (extender), matting agent, solvent
(or carrier fluid), pH buffer, anti-foam agent, freezethaw
agent, biocide, UV-absorber and possibly more
additives.
This development confronts us with a difficult
situation. Is it realistic to reconstruct paints with
such complicated formulas? What is our objective in
reconstructing these paints?
To the first question, the answer is “probably not”. The
second question is subjective in that every professional
may have his or her own opinion. One answer could
be, “we want a reconstruction to show the appearance
of the original”. Appearance in this case means gloss,
colour, evenness or signs of application mode, thickness
and deterioration patterns. All these characteristics
influence our impression of a surface. Thus, the
combination of these parameters must be taken into
account when working with visual authenticity as
mentioned above.
The general assumption is that apart from the pigment,
the binding media has the greatest influence on the
appearance of a paint film. The binding media is not
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just the dominant ingredient, but also determines most
of the characteristics of the paint. In fact, just the binder
and carrier fluid (which will evaporate) constitute
between 35 and 75% of modern paint. And with the
pigment and extender we are up to between 72 and
96% by mass [7,8].
Figure 1 shows the content of binder in a styrenebutadiene
paint called Spred Satin. Produced under
license from The Glidden Co., it was the first latex
(emulsion) paint to be introduced on the Danish
market. On this photo the producer, Sadolin &
Holmblad, wanted to show the customer that in spite
of the very low viscosity of the paint, the product had
a high content of binder. At that time, this seemed a
contradiction, and was a sensational feature of the
plastic emulsion paint.
A realistic reconstruction of paint, with an appearance
close to the original, may thus be one in which the
binder, solvent or carrier fluid, pigment and extender are
historically correct. To be able to assess the possibilities
of producing such a reconstruction, information about
the most important materials is required.
The most important paint binders
in Denmark during the twentieth
century
Table 1 shows an overview of some of the most
important binders as they occur in Denmark. Below is
Figure 2, in which the binders are arranged in a time
line.
Pigments during the twentieth
century
Organic pigments
Development of synthetic organic pigments
commenced in the second half of the nineteenth
century, and by the turn of the century they were
widely used. They became popular because of
the bright hue and relatively good light-fastness
compared to the natural organic pigments. Yet
especially the red ones were known by painters
to bleed when over-painted, a problem which
was vigorously discussed in the first half of the