Abstract:
Dampness is a common condition in old
buildings and, accordingly, many paint systems specific
for this type of building allow for application on walls
with nonnegligible moisture content. In spite of that,
performance evaluation of these paints is normally
carried out using dry substrates or even on free paint
films. This article presents research performed on 16
commercial paint systems: seven silicate, three silicone,
three hydro-pliolite and two lime-based systems, as
well as one common vinyl emulsion paint that served as
reference. Each paint was applied and cured both on
dry and on damp mortar substrates. The test specimens
were subjected to water vapor permeability tests and
evaporative drying tests. The following conclusions
could be drawn: (i) the way paint systems influence the
drying of the substrate, to which they were applied and
where they cured, may vary significantly depending on
the moisture content of that substrate; (ii) vapor
permeability, measured with specimens applied and
cured on dry substrate, may be an acceptable way of
predicting a paint’s influence on drying, provided that
the paints are applied and cured on dry substrate or
that their characteristics are not significantly affected
by the moisture content of that substrate.
