# Research on the Organic Binders in Archaeological Wall Paintings
## 4 Exploring Research Results
### Invasive Techniques
Samples collected from wall paintings from different rooms were studied by Fourier Transform Infrared Spectroscopy and GC-MS. Analytical results show that these Roman wall paintings were made without the use of lipid and protein materials, presumably in the _affresco_ technique. In addition, wax, eggs and animal glue have been identified, the presence of which is due to previous restoration work [80]. A paper has been published on Villa of the Papyri in Herculaneum, in order to know the presence of an organic binder. The authors found egg, by means of GC-MS, in some samples, where the pigment required _a secco_ technique. They also investigated the presence of wax employed as superficial treatments of the wall painting. The fact that they didn't detect beeswax in all the analyzed samples give further information that the encauste technique was not used for the realization of the wall paintings of the Vesuvian area [81]. An interesting work examined the wooden roof and ceiling of the House of the Telephus Relief in Herculaneum. The goal of this study was to assess the techniques used to decorate the wooden ceiling, using a multianalytical approach (SEM/EDX, FT-IR spectroscopy, GC/MS and Py-GC/MS). The results showed that a tempera painting has been chosen. Egg was employed as binding medium, as confirmed by the analysis of the proteinaceous fraction and by the presence of cholesterol. In only one sample, casein  
Figure 1: The picture of [PERSON] in room 42 (the antechamber of the so-called erotic cubiculum) of _Insula_ del Centenario, Pompeii, Italy, where sample 42/2 was collected. was determined, probably employed as an adhesive. The paint layer was directly applied the wooden ceiling, without a preparatory stratum. A motivating aspect of this paper is that the authors argue that, based on chemical investigations, this is the first time it has been possible to prove that egg tempera has been used to decorate wooden architectural elements [82]. [PERSON] highlights the fact that investigations of ancient Roman wall painting show the difficulty of efficiently extracting organic binders. The author considers that sometimes it can be considered an affresco painting, due to the lack of results obtained, when the organic binder may be present, but not identified for purely analytical problems. The use of inappropriate extraction methods for ancient paint supports can cause the transformation of some components of the binder, producing an incomplete characterization of the composition He pointed out that chemical analyses of Roman wall painting have identified other types of paint binders and that there is a clear difference between the results of one research group and the other. These factors could be related to the difficulty of extracting ancient painting binders and, in addition, the influence of microbiological contamination. The absence of data in most studies on the efficiency of extraction actions used in antique samples and the effect of microbial contamination may give rise to doubts about some of the results obtained [8]. [PERSON] et al. (2012) studied eight samples of Roman wall paintings from three archaeological sites in Spain using full attenuated reflectance Fourier transform infrared spectroscopy and GC-MS, in order to recognize organic binder. It was seen the samples featured beeswax and soap. These results show for the first time that Roman artists used in mural paintings a water-soluble encaustic paint of beeswax and soap. This research highlights that wax and soap encausto could be a common pictorial technique among Roman artists. The authors believe that the composition found may correspond to an ancient encaustic formulation searched for the last five centuries by many artists [83]. [PERSON] et al. (2017) present a multi- methodological investigation of mural paintings from Cuma, a Roman archaeological. They report the results on mortars, pigments and binding media, focusing on differences between an indoor (_domus_) and outdoor fabrication (a temple, _Tempio con Portico_).