# Characterization of Waves in the Roman Wall Paintings of the Herculaneum Site (Italy)
## 4 Conclusions  
The wall decorations of the houses of the Vesuvian area, Italy, constitute a unique historical document for the knowledge of Roman wall paintings. In this study, a multi-analytical approach by FTIR, Raman and GC/MS techniques was proposed for the detection  
Figure 8: Weight percentage of the fatty acids, alcohols and odd and even hydrocarbons, in contemporary reference waves (**a**) and in archaeological samples (**b**). \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & **Fatty Acids** & **Alcohols (A)** & \multirow{2}{*}{**FA/A**} & **Odd Alkanes** & **Even Alkanes** & \multirow{2}{*}{**OA/EA**} \\  & **(FA) (wt \%)** & & & **(OA) (wt \%)** & & **(EA) (wt \%)** & \\ \hline AC 17 & 2.98 & 8.61 & 0.35 & 30.84 & 57.61 & 0.54 \\ AC 20 & 1.26 & 3.28 & 0.38 & 35.87 & 59.58 & 0.60 \\ AC 25 & 10.01 & 4.65 & 2.16 & 33.47 & 51.89 & 0.65 \\ \hline Beeswax & 10.43 & 25.87 & 0.40 & 62.69 & 1.58 & 60.74 \\ Spermat & 21.08 & 79.12 & 0.27 & - & - & \\ Carnauba & 55.51 & 37.54 & 1.48 & 6.62 & 0.33 & 20.06 \\ Candicillin & 15.04 & 14.09 & 1.07 & 70.08 & 0.79 & 88.23 \\ Lanoline & 41.75 & 58.25 & 0.72 & - & - & \\ F-Candelilla & 22.06 & 7.50 & 2.94 & 28.82 & 40.72 & 0.71 \\ Microcrystalline & 14.61 & - & - & 56.44 & 28.95 & 1.95 \\ Paraffin & - & - & - & 48.50 & 51.60 & 0.95 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Weight percentage (wt %) of fatty acids (FA), alcohols (A), odd alkanes (OA) and even alkanes (EA) and FA/A and OA/EA ratios found by GC data in wall painting samples and contemporary reference waves. and characterization of the waxes in the wall paintings of three Herculaneum houses: the House of the Skeleton, the House of the Deer and the House of the two Atriums. Spectroscopic FTIR and Raman investigations, carried out on the surface of the samples, showed the characteristic bands of the waxes. It was not possible, with these techniques, to identify the type of wax. By means of GC/MS, the characteristics of beeswax are clearly detected even if, obviously, in archaeological samples, there are variations in the distribution of the constituents of beeswax (hydrocarbons and fatty acids) with respect to contemporary beeswax, due to aging and degradation phenomena suffered over time. It is clear that the results of the GC/MS measurements do not provide information on the distribution of waxes in the samples. For this reason, the original use of beeswax by the Roman artist can neither be confirmed nor excluded. In addition to beeswax, by GC/MS, the triacontane and hentriacontane hydrocarbon markers of candellilla wax (imported in Europe after its discovery in the Americas) were found. An artificial wax, such as formulated candellilla (often used in a mixture to reinforce natural waxes), was also detected. In light of these results, it makes sense to conclude that a mix of beeswax and candellilla (combined with formulated candellilla) has been applied over the surface as a protective layer or to enhance the brilliance of the colors. It is well known that the application of a layer of wax on painted surfaces, to make them brighter, was a widespread practice of restoration since the beginning of the archaeological excavations conducted in the Vesuvian area in the nineteenth century. By Raman and FTIR spectroscopies, hematite and Egyptian blue were identified, confirming the high quality and value of the decorations found in the domus Herculanensis. Conceptualization, L.B. and A.C.; methodology, L.B. ; validation, L.B., A.C. and P.P.L. ; formal analysis, L.B., M.C. and C.G. ; investigation, L.B., M.C., C.G. and G.P; resources, A.C., C.G., P.P.L. and G.P. ; data curation, L.B. and M.C. ; writing-original draft preparation, L.B. ; writing-review and editing, L.B., A.C. and P.P.L. ; visualization, A.C. and L.B. ; supervision, A.C. and P.P.L. All authors will be informed about each step of manuscript processing, including submission, revision, revision reminder, etc., via emails from our system or the assigned assistant editor.