of a sample of an encaustic mummy portrait also
showed strong evidence of the presence of beeswax
and soap, together with some absorption bands
that could not be identified. This is the first study
that finds evidence through chemical analysis of
the use of a common painting technique in Roman
wall paintings and Egyptian mummy portraits.
This unknown painting technique, unreported so
far in the scientific literature,‡ would be based on
beeswax and soap. Egyptian mummy portraits are
the best known examples of the ancient encaustic
painting technique, whose composition remains
subject to debate, as the two main theories about
its composition – wax paint applied in molten state
and wax saponified with an alkali – have not been
confirmed by chemical studies and do not allow
an accurate reproduction of paint strokes shown
in some encaustic mummy portraits. The strong
evidence of the use in an Egyptian mummy portrait
of an encaustic paint made of beeswax and soap
provides an alternative theory on the composition
of an ancient water soluble encaustic paint. The
support of this theory is not limited to the results
obtained by chemical analyses; it also relies on
experimental studies showing that wax-and-soap
paint allows the artist to reproduce characteristic
paint strokes in encaustic mummy portraits with
great accuracy. The alignment of the peaks characteristic
of beeswax and soap shown by ATR FT-IR
spectra of the eight Roman wall paintings and the
mummy portrait analyzed strongly suggests that the
Roman wall paintings analyzed were also executed
with a water soluble encaustic made of beeswax
and soap. These results agree with other studies
of Roman wall paintings in Pompeii, Herculaneum,
Marsala (Italy), Merida and Complutum (Spain)
which also identified the presence of beeswax
and soap. The use in Roman times of wax-andsoap
encaustic in wall and easel paintings that
are geographically and temporally distant (From
Egypt to Spain from the 1st century BC to the 2nd
century AD) suggests that this type of encaustic
had a generalized use in Classical Antiquity. This
widespread use strongly suggests that the watersoluble
wax-and-soap encaustic paint identified in
this study is a lost cold encaustic painting technique
used by the Greco-Roman artists and whose reconstruction
has been objective of artists and researchers
during the last five centuries. As wax-and-soap
encaustic is a painting technique unknown before
the publication of this article, the identification
of beeswax and soap in the binding medium of
ancient paintings or polychrome objects suspected
of being forgeries provides a strong argument in
favor of their authenticity. The results obtained from
the chemical and experimental studies on Roman
wall painting techniques performed in this study
strongly suggest that the theory of the generalized
use of the fresco painting technique in Roman wall
paintings should be revised.
Further studies are necessary in order to broaden
our knowledge on the composition of the wax-andsoap
encaustic painting technique in antiquity, its
variations according to local artists’ schools, its
geographical and temporal boundaries, its aging
and degradation processes which would allow the
development of conservation treatments for ancient
paintings executed with this. Current state of the first
encaustic wall painting on lime mortar executed in
modern times (Jose Cunı, 1962), showing no signs
of decay in the painting. House in San Lorenzo
del Escorial, Madrid. With the exception of the
article by J. Cunı and J. Cunı, Archivo Espa~nol de
Arqueologıa, 1993.
Anal. Methods—This journal is The Royal Society
of Chemistry 2012. Downloaded by Columbia
University on 21 February 2012 Published on 21
February 2012 on http://pubs.rsc.org | doi:10.1039/
C2AY05635F View Online technique, and its possibilities
as a new painting technique for contemporary
artists.
All About Encaustic
23
Winter
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