During new decades, a speculation that fresco was a many common portrayal technique in Roman murals has enjoyed ubiquitous acceptance among specialists [1–۳]. As a result, it is now common use in museums to state that fresco was a technique used in Roman murals within their collections [4–۱۰]. However, new studies of a paint media used in these paintings seem to doubt a effect of a fresco theory, as many stream analyses detect a participation of organic binders. These binders are as sundry as wheatpaste, egg and emulsified beeswax. These studies have non-stop a new viewpoint on Roman wall breathing techniques, that is a theme of a benefaction work.
The farrago of paint media identified seems to advise a use of several portrayal techniques in Roman murals. According to this hypothesis, it would be approaching that, when studies analyse samples from opposite archaeological areas and periods, several forms of binders will be identified. However, discordant to those expectations, a formula of such studies have proven rather homogeneous.
Corso, Gelzo and co-workers analysed a combination of binders in unrestored Roman wall paintings from Villa Imperiale, Pompeii (first century AD) [11], from Liternum, Italy (first century AD) [12], and in fragments of a 4 Pompeian styles (200 BC to 79 AD) from a Marcus Fabius Rufus House, Pompeii [13, 14]. The formula prove a use of a wheatpaste-based paint in all a samples that authorised for a marker of a binder. These studies are substantially a customarily ones detecting this technique Roman wall painting. Yet remarkably, this odd technique was found in many paintings complicated by this investigate group, lifting questions about probable causes behind a singleness of these results.
A investigate organisation with that a author has collaborated analysed paint binders in unrestored Roman wall paintings from Ampurias, Cartagena, and Baelo Claudia, Spain, dating from a initial century BC to a second century AD [15]. In all a samples complicated a paint middle was hypothesized to be emulsified beeswax. This investigate of paint samples incidentally comparison from opposite archaeological areas seems to prove to endless use in Roman murals of a folder done from emulsified wax. This endless use seems to be reliable by identical formula performed in a investigate carried out by a same organisation on unrestored Roman wall paintings from Mérida, Complutum and Marsala that will be discussed later. As in a box remarkable in a prior paragraph, these formula are unsuitable with those found in a literature, as a participation of emulsified polish has not been reported in other studies.
Another investigate organisation has serve analysed a binders in wall paintings during a Villa of a Papyri [16], and in a embellished wooden roof during a House of Telephus Relief, both in Herculaneum (and dating to before 79 AC) [17]. In both paintings, formula indicated a use of egg tempera. This organisation has also analysed Mycenaean wall paintings during a Palast of Nestor in Pylos, Greece (before 1180 BC) [18], on an Etrurian wall portrayal (fourth century BC) [19], and on an Etrurian sarcophagus of embellished alabaster (fourth century BC) [20]. Again, egg tempera was hypothesized, suggesting widespread use of this technique in ancient Mediterranean cultures, both in wall portrayal and on other forms of supports. It is poignant that a studies mentioned in a dual preceding paragraphs have not rescued a participation of egg in any of a samples studied, and that some investigate privately reports miss of egg in a murals of Pompeii and Herculaneum [21]. As in a dual prior cases, a formula performed by these researchers were unchanging with any other, though unsuitable with commentary by other teams.
Elsewere, Casoli and co-workers analysed a organic binders in wall paintings from several houses in Herculaneum [22] and Pompeii [3], and a portrayal technique was hypothesized as being fresco in all a samples. This technique has not mostly been identified in studies analysing organic binders in Roman wall painting. Therefore, a ratio of samples ascribed to fresco in these studies seems to be remarkably high compared to other studies, This high ratio between samples ascribed to a specific portrayal technique by a sold investigate organisation is a bewildering evil common to many studies of Roman portrayal techniques, again rising questions about probable causes.
Considering a opposite paint media identified in Roman wall painting, a likeness in a binders rescued by any organisation in samples of several wall paintings is value mentioning. This likeness competence advise a existence of a common portrayal technique, characterized differently by any investigate group. The supposition of a existence of a widespread portrayal technique serves as a fanciful credentials for a stream speculation of fresco, formed on a common technical characteristics displayed by Roman wall paintings.
The clustering of any form of folder around a specific investigate group, shown in Table ۱, appears rarely unlikely. It competence prove a participation of confounding factors in a methodical proceed used, so causing lopsided results.
Table ۱
Relationship between descent protocols used and portrayal techniques hypothesized
aResearch teams pity members
The probable participation of these factors is serve emphasized when opposite researchers analysing a same samples come to opposite conclusions. One applicable instance can be found in a Roman wall paintings from Casa del Mitreo in Mérida, ascribed to emulsified beeswax paint by one investigate organisation and to fresco by another [23, 24].
Which intensity confounding factors could be impacting a obscure formula performed in analyses of Roma wall paint media? Most studies of ancient binders acknowledge substantial problems in accurate marker due to a plunge of a strange compounds, a reduction and communication of materials benefaction in a preparation, paint and protecting layers, and a tiny representation distance [25–۲۷]. Besides these factors, mostly taken into comment in such studies [28–۳۴], are dual other factors, not customarily deliberate in literature, that competence have a wilful change on results: a problem in good extracting organic binders from ancient paint samples, and a participation of organic element due to microbiological contamination.
The initial time a author of this work carried out a investigate to establish a combination of binders in Roman murals, a descent process used was grown in a same laboratory in that a investigate was performed1, and it was successfully used to analyse a combination of paints dating from new centuries, as had been ordinarily complicated in that laboratory [35]. The Roman samples analysed were taken from unrestored Roman wall paintings from Mérida and Complutum (in Spain) and Marsala (in Sicily). The investigate of these samples by GC–MS showed no participation of organic material, suggesting that an fake paint middle had been used. This information together with a marker of calcium carbonate in a paint layers seemed to prove that a Roman murals underneath investigate were embellished with fresco. In sequence to check for participation of organic compounds in a samples, a fake excess of a extractions was subsequently analysed by FTIR. The spectrograms indicated participation of organic materials, suggesting that a descent process was not suitable for ancient paint binders. After successive use of a some-more fit descent method, investigate by GC/MS authorised a supposition that emulsified beeswax could have been a paint middle used in all a murals analysed [23].
The problem in extracting ancient paint media and a probable change in a methodical formula suggests that this emanate should be taken into full comment when characterizing ancient portrayal techniques. However, a deficiency in many of a studies of remarks on a use of descent methods suitable for ancient binders, or of tests to consider their efficiency, competence beget doubts about a bearing of a descent methods used in some analysis.
Table ۱ shows that some studies are carried out with descent yields of reduction than 0.1% of a paint weight. This volume of folder would seem deficient to repair a colouring to a support, or to explain a fortitude of a painting, so permitting a supposition that partial of a folder competence not have been extracted, that would furnish an deficient characterization of a composition. This probability competence serve advise a couple between a descent methods used and a formula obtained, creation advisable an comment of a potency of a descent methods used in characterizing ancient paint media.
Moreover, a common participation of microorganisms in ancient wall paintings can yield an additional source of organic element that could be mistaken as partial of a strange binder. This presence, not generally deliberate in analyses of Roman wall painting, competence cgange a formula of an analysis, quite when total with low descent yields.
Studies of ancient organic binders that brand a portrayal technique as fresco are of sold interest. This portrayal technique does not need any organic binder, so it would seem reasonable to pertain a miss of showing of such binders to a portrayal executed in fresco. However, if a descent process used was not fit adequate to detect a participation of an ancient organic binder, a conclusions reached could be inaccurate.
In sequence to consider this possibility, it is useful to examination a paint investigate in Greco-Roman speckled sculpture. As a paint used in sculpture requires an organic folder to repair a pigments to a support, a miss of marker of organic binders has to be ascribed to a use of a fresco portrayal technique, and competence instead be taken as explanation of a problem to impersonate ancient paint media. A examination of a novel on ancient speckled sculpture shows that, often, studies analyse customarily pigments [36–۳۹] or are incompetent to brand a folder [40–۴۲].۲ The outcome is a miss of bargain of a portrayal techniques used in Greco-Roman speckled sculpture, as epitomised by Kenneth Lapatin: “ancient binders have nonetheless to be identified, and a strange portrayal and finishing techniques are distant from good understood” [۴۳]. Transferring these formula to picture painting, it could be hypothesized that a reason some chemical analyses of Roman wall paintings have not rescued any organic folder is due not to execution in fresco, though to a problem in extracting a strange paint medium.
Also notable are studies of Roman wall paintings in that organic compounds are rescued in some samples though not in others found in excavation. As a compounds identified in these studies are customarily located on a utmost covering of a samples, it seems reasonable to hypothesize that a strange technique was fresco, and that a participation of organic element is due to complicated charge treatments. This is a box in a aforementioned studies by Casoli and colleagues. The showing in these analyses of organic compounds such as wax, egg or animal glue seems to endorse a use of a suitable descent method. However, if a process used was not suitable to descent of ancient binders, successive investigate competence detect a participation of complicated binders nonetheless they were incompetent to detect a participation of ancient paint media. Therefore, in this case, it would be required to establish a potency of a descent process used.
The many vicious effect of a miss of information on a potency of a descent methods of Roman paint binders, and a probable change of microbial contamination, is a problem in meaningful during this prove either some formula are inaccurate, and to what extent, fomenting an altogether doubt on Roman wall portrayal techniques. Such doubt can impact not customarily on a believe of Roman art and technology, and a fit use of resources in paint media studies, though also a charge of a paintings, given a “knowledge of a strange portrayal techniques [… is] essential in a doing of suitable charge projects” [۴۴–۴۶].۳۴
