pigmented colorants: dependence on media and time - Cornell ...

materials–an artist will know from experience how different pigment-media com-
binations behave. While this problem is quite difficult, most paint media can be
reworked until the desired result is achieved. The inherent problem with fresco is
that a dried brushmark is permanent and cannot be reworked. Thus, one needs to
understand the time dependencies to correctly match colors between sessions. The
color matching problem can readily be seen in the hue discrepancies in Masaccio’s
giornate in his Expulsion from the Garden of Eden (Figure 1.2).
The same problem occurs with the conservator’s practice of in-painting on
losses of paintings. Occasionally, a painting will experience damage to the surface
whereas a portion of the work has chipped off. One common technique of is to
first disguise the loss with filling to regain the surface topology. The new surface
is then retouched to match the current color, which places a large responsibility
on correctly identifying the original pigments. Further, the fresh paint must be
mixed such that the fresh mixture will age at a similar rate to that of the original
surrounding colors. This is difficult as the original artwork will be at a much later
stage in fading and will change at a much different rate to that of fresh paint.
While a conservator may have carefully matched an in-painting section, the false
area may display itself later in its own fading cycle. The difficulty of retouching
artworks is further documented in [Sta85].
There is an importance consequence of the artist controlling the initial condi-
tions of a paint. The artist knows the desired color for his or her artistic vision.
Then, one can use knowledge of the evolution of a paint in order to modify the
fresh paint such that the aged paint will be the desired result. This changes the
conception of the term “artwork”, as the original is not necessarily the creative
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vision. Rather, the evolving work moves incrementally closer to the artist’s intent