Alkyd resins are synthetic resins that are made in combination
with oil, for example linseed oil or soya bean oil. The oil makes
the alkyd resin susceptible to yellowing under the effect of light.
As a binder for paint the resin is dissolved in white spirit. Due
to the presence of both oil and white spirit the drying is chemical
as well as physical. As a result of the evaporation of the white
spirit the brushstroke will partly disappear.