Multidisciplinary Study of Lime and Gypsum Plasters from the Paphian Region – Comprehensive Dataset

Context

While plasters are a widely studied material across archaeological contexts worldwide [1, 2, 3, 4, 5, 6, 7, 8], research concerning this category of findings is still scarce in the frame of Cypriot archaeology [9]. This scarce availability of knowledge and data prompted the initiation of the present project as part of the Marie Curie Innovative Training Network “PlaCe: Interdisciplinary studies of pre-modern Plasters and Ceramics from the eastern Mediterranean”. In order to maintain a certain degree of feasibility over the limited three years, a restricted geographical area was selected around the site of Nea Paphos, in order to begin the characterization process in a specific region and later, possibly, expand it island-wide with future research. The present research covers the main archaeological sites in the area of Paphos (Figure 1) during the period between the end of the Bronze Age (approximately 1600 BCE) and the Roman times (until approximately the 3^rd century CE, with sporadic samples dating to the 4^th and 6^th). The selected sites represent the most significant settlements for the time period considered, and – thanks to a comprehensive and thorough documentation – the most relevant for the study of plasters and mortars.

Figure 1

The objective of this research was the characterization of a hundred selected mortar samples in order to create a systematized database and grouping method, which will allow expanding the research on the island while simultaneously having a common terminology and set of characteristics. In principle, the aim was to create a structure similar to the one adopted for the study of ceramics, which is based on fabrics that can be compared across time and spaces, while maintaining constant pivotal characteristics.

Spatial coverage

Description: samples were collected in Cyprus, specifically in the region of the Paphos District, in the following localities: Yeronisos Island, Kissonerga-Skalia, Kouklia-Palaepaphos (loc. Hadjiabdoulla), and Paphos.

Northern boundary: Yeronisos, 34°53′57″N 32°18′41″E

Southern boundary: Palaepaphos (loc. Hadjiabdoulla), 34°42′23″N 32°34′58″E

Eastern boundary: Palaepaphos (loc. Hadjiabdoulla), 34°42′23″N 32°34′58″E

Western boundary: Yeronisos, 34°53′57″N 32°18′41″E

Temporal coverage

1600 BCE – 400 CE ca.

Steps

The collected samples were mechanically cleaned using simple soft brushes; in a few cases (especially for the samples from Yeronisos Island), compact soil encrustations were removed with the aid of a scalpel. The cleaned samples were labelled and photographed with a standard camera. A preliminary examination under a stereomicroscope was performed in order to select the most suitable and representative samples for the subsequent analytical procedures. 68 samples were cut with a circular table saw and sent for the preparation of blue-stained, uncovered, polished thin sections.

Optical microscopy and cathodoluminescence: The thin sections were analysed through a standard polarized light microscope (PLM) – Olympus BX53M with an Olympus DP27 digital camera – to study the fabric, pore structure, composition and technological features of each sample [10, 11, 12]. A “cold cathode” type Mk 5-2 was associated with the microscope to further investigate binders and binder-related particles.

Scanning Electron Microscopy: High-resolution images, as well as the elemental composition, were obtained via scanning electron microscopy (SEM-EDS) analysis on a selection of 30 thin sections. SEM-EDS analyses were performed on carbon-coated samples with two different instruments: the first half of the samples (package 1) was analysed with a Tescan MIRA II LMU scanning electron microscope with an energy-dispersive analytical system (Bruker AXS) under the following conditions: back-scattered electron mode (BSE) with electron accelerating voltage corresponding to 15 kV, at a WD of 15 mm, in high vacuum. The chemical composition was quantified by Brucker Esprit 2.5 software, without standardization. The analytical results were expressed in oxide form. The second set of samples (package 2) was analysed with a Carl Zeiss EVO 25 scanning electron microscope coupled with two energy dispersive analytical systems (Oxford Instruments) under the following conditions: back scattered electron mode (BSE) with electron accelerating voltage corresponding to 20 kV, at a WD of 8.50 mm, in high vacuum. The chemical data were quantified by Aztec 5.1 software, and the results were expressed in oxide form.

X-Ray powdered diffraction: To acquire mineralogical data, a small fraction of 55 selected samples was grounded to analytical fineness. Each sample was firstly gently crushed in a mortar and sieved through a set of different sieves ranging from 90 to 63 µm. The fraction above 90 µm was considered to be corresponding mainly to the aggregates (labelled as “_a”), while the fraction below 63 µm was considered to be rich in binder (labelled as “_b”) [13, 14]; occasionally, the bulk sample was measured without sieving (labelled as “_t”). Before the XRD analysis, an internal standard (ZnO, 10 wt.%) was homogenized with the sample. Data were collected on a diffractometer D8 Bruker Advance pro (Cu Ká radiation, 40 kV and 40 mA) with 0.01°C step size 2ϴ and counting time 0.4 s/step. Quantitative phase analysis (QPA) to determine crystalline and amorphous phases was performed by the Rietveld method [15] using Topas 4.2 software from Bruker AXS.

Thermogravimetry: Derivative thermogravimetry was performed on the binder-rich fraction of the samples with a TA Instruments Discovery SDT 650, under the following conditions: nitrogen atmosphere, heat rate 20°C/minute, temperature range 50–1000°C. TG, DTG and heat flow curves were collected and analysed with MS Discovery; special focus was directed towards the regions between 50–250°C (detection of gypsum), 250~550°C (estimation of hydraulic phases) and between ~600–850°C (carbonate decomposition) [14, 16]. When the spectrum displayed possible traces of organic materials the sample was analysed again with thermogravimetry coupled with a mass spectrometer (TGA-EGA, evolved gasses analysis), measuring the eventual exothermic processes in nitrogen and air atmospheres. The detection and identification of evolved gases were realised by quadrupole mass spectrometry MS Discovery.

Raman: Raman spectroscopy was performed on a small pool of samples with the specific purpose of identifying the pigments contained in the thin, superficial layer. The samples were analysed at the Faculty of Chemistry of the University of Warsaw: the spectra were obtained on a Dispersive Raman Spectrometer Nicolet Almega equipped with confocal microscope. All spectra were recorded with use of the 780 nm laser and high-resolution grating (1200 line/mm). The power of the laser on the sample was reduced to 30–50% in order to avoid sample overheating and consequent damage. The exposure time was set to 30 s; each spectrum was a sum of two independent scans. Samples were placed on the microscope stage, and the laser was focused on the selected spot with a diameter of 1–2 μ². Samples NPA 27, 28, and 29 were analysed with a Raman microscope DXR3xi (Thermo Scientific) with an excitation laser at a wavelength of 532 nm and a power of 0.5–10 mW on the sample (the power was adjusted to avoid damaging the samples), in the spectral range of 1800–50 cm^–1. Several maps and points were measured from various parts of the sample surface with a measurement step of 2–5 µm.

Fourier-transform infrared spectroscopy: FTIR spectra were recorded on IS5 Nicolet Infrared Spectrometer equipped with GladiATR accessory with diamond crystal. Each spectrum was averaged from 128 scans. The spectral resolution was 2 cm^–1. Spectra of samples NPA 27, 28, and 29 were acquired in attenuated total reflectance (ATR) mode using the iZ10 module of a Nicolet iN10 laboratory spectrometer (Thermo Scientific), equipped with a DTGS detector and KBr beam splitter. The spectral range covered 4000–525 cm^–1 with a resolution of 4 cm^–1, and 64 scans were accumulated. Prior to measurement, the surface layer of each sample was gently scratched, and the obtained powder was deposited onto a single-reflection diamond ATR crystal.

Organic residue analysis: measurements were carried out using UHPLC Dionex Ultimate3000 RSLC nano (Dionex, Germany) connected with mass spectrometer ESI-Q-TOF Maxis Impact (Bruker, Germany). 10 µL of peptide solution were previously dried and then dissolved in 97:3:0.1% mixture of water:acetonitrile:formic acid. Consequently, they were loaded on trap column Acclaim PepMap 100 C18 (100 μm × 2 cm, size of reverse phase particles 5 μm, Dionex, Germany) with flow rate of mobile phase A 5 μL/min for 5 min. The peptides were eluted from trap column to analytical column Acclaim PepMap RSLC C18 (75 μm × 250 mm, size of reverse phase particles 2 μm) using following gradient: 0 min 3% B, 5 min 3% B, 85 min 50% B, 86 min 90% B, 95 min 90% B, 96 min 3% B, 110 min 3% B. Mobile phase A was 0.1% formic acid in water and mobile phase B was 0.1% formic acid in acetonitrile. The flow rate during gradient separation was set to 0.3 μL/min. Peptides were eluted directly to the ESI source – Captive spray (Bruker Daltonics, Germany). Measurement was carried out in positive ion mode with precursor selection in the range of 400–2200 Da; from each MS spectrum up to ten precursors were selected for fragmentation.

Peak lists were extracted from raw data by Data Analysis (Bruker Daltonics, Germany). Proteins were identified using Mascot version 2.2.04 (Matrix Science, UK) by searching protein database Uniprot version 20110-12. Parameters for database search were set as follows: Oxidation of methionine and hydroxylation of proline as variable modifications, tolerance 50 ppm in MS mode and 0.05 Da in MS/MS mode.

Sampling strategy

Whenever possible, samples were collected from all the plastered features of each site, avoiding aesthetical or structural damages to the buildings. Considering that one of the key questions of the project was whether distinct types of plasters were produced to fulfil specific functions, samples were collected from each functional category (namely, masonry mortars, waterproofing mortars, wall plasters and floor structures). Samples were not collected in a standardised quantity, but proportionally to the preserved amount in situ. When possible, small blocks of around 5 cm in length and 2 cm in thickness were collected and stored in sealed plastic bags. For each sample, the specific location of collection was documented in addition to any relevant information concerning the associated structure, such as the preservation extent and status, masonry characteristics and chronological data.

Quality Control

In order to guarantee high quality results, the team adopted the following strategies:

• – Carefully crafted sampling strategy: multiple samples from the same structures were collected in order to guarantee minimum impact from the heterogeneity of the materials;

• – With the exception of one sample (NPT 11a), a fraction of each sample was preserved in order to allow for repetition of analysis;

• – The analytical procedure selected followed the direction of the RILEM-TC committee, allowing for a standardized process [17];

• – Any conclusion was drawn from comparing multiple analytical outcomes.

Constraints

Constraints and limitations mostly relate to the formulation of the sampling strategy. The major criteria for sampling selection was representativeness; however, in several circumstances, it was not possible to collect samples for every structure of interest due to the incurrence of structural and aesthetical damages. The selection of the suitable analytical techniques was also determined by the restricted quantity of material available; in fact, several of the samples had to be taken directly in situ and were, therefore, of limited dimensions to avoid damaging the associated cultural heritage. Plasters and mortars are extremely heterogeneous materials; thus, selection of small amounts of samples can hinder the representativeness of the whole product.

We would also like to note that in several circumstances – specifically when the sample was not collected while still attached to the feature but rather as a loose fragment – the context and associated materials inferred the dating, as no radiocarbon dating was performed at this time.

Object name

The dataset is divided into two folders: “Site plans&samples” and “Analysis”.

“Site plans&samples” contains a PDF document (.pdf) with detailed descriptions of the samples, their systematization, a short analysis tracker, and the plan of the sites with marked sampling locations; a PDF document with the list of abbreviations; and two Excel tables (.xlsx) listing all the samples (“List of samples with brief description”) and the analyses performed on them (“List of analyses”).

“Analysis” folder contains a series of sub-folders with the results of the analytical process, which can be summarized in the following way:

1. Optical Microscopy

   1. OM_scans: folder containing the full scans of each of the studied thin sections.

   2. OM_general: folder containing selected photomicrographs (.jpg format) for each sample. The title explains the contents of the image. Abbreviations list is provided in the folder “Site plans&samples”.

2. Cathodoluminescence

   1. Cathodoluminescence_JPG: folder containing the images (.jpg format) obtained on the cathodoluminescence microscope

   2. Cathodoluminescence results_PP: PDF file summarizing the results and providing descriptions for the most relevant figures of folder 2.a.

3. XRD: folder containing an Excel spreadsheet (.xlsx) summarizing the XRD-QPA results.

4. Thermal analysis

   1. TA_DSC: folder containing the images (.tiff format) of the spectra obtained using thermal analysis (differential scanning calorimeter mode). The files are named as “SAMPLE ID no_b/m/t/l”, where b = binder fraction, m = binder fraction with partial contamination of aggregate fraction, t = binder+aggregates fractions, l = lump.

   2. TA_EGA (DF): folder containing the report of the TA-EGA analysis in Word (.docx) format. All the analyses were performed on the binder-rich fraction of the sample (_b).

   3. TA_quantification (PP_DF): excel table summarizing and elaborating the data.

5. SEM-EDS

   1. SEM_TIF: folder containing selected images (.tiff format) obtained in BSE mode divided in folders identified with the sample’s code. The folder is sub-divided into two packages, which are used to distinguish the different sets of instruments employed:

      1. Package 1: for the samples analyzed with the TESCAN MIRA II SEM.

      2. Package 2: for the samples analyzed with the Zeiss EVO 25 SEM.

   2. SEM_XLSX: folder containing two Excel tables with all the SEM-EDS quantified data. Data is divided into two groups reflecting the use of two different sets of instruments and analytical parameters (specified in each Excel document).

6. Raman

   1. Raman_CSV: folder containing all the spectra collected on the samples analyzed (.csv format).

   2. Raman_SPA: folder containing all the spectra collected on the samples analyzed (.SPA format).

   3. Raman_TIF: folder containing selected image(s) of the elaborated and/or compared spectra (.tiff format).

   4. Raman and FTIR results_GZ_PP: analytical report summarizing the results and data interpretation.

   5. Raman results_PM: analytical report summarizing the results and data interpretation of samples NPA 27, 28, and 29.

7. FTIR

   1. FTIR_SPA: folder containing all the spectra collected on the analyzed samples (.spa format).

   2. FTIR_TIF: folder containing selected image(s) of the elaborated and/or compared spectra (.tiff format).

   3. Raman and FTIR results_GZ_PP: analytical report summarizing the results and data interpretation.

   4. FTIR results_PM: analytical report summarizing the results and data interpretation of samples NPA 27, 28, and 29.

8. Organics: folder containing a Word document (.docx) summarizing the results of organic analysis.

An additional folder containing the photos of the samples and their context has been added to the repository as supplementary material. The supplementary material folder is divided into sub-folders for each archaeological site and sample. “Context” includes the photographs collected on site (except for the samples from Yeronisos and NPA 21–30, which were collected from storage rooms); “macrophoto” includes the photographs of the samples after a first soft cleaning; “microscope” includes the pictures taken with the stereomicroscope.

Data type

The dataset includes primary data collected for Raman, FTIR, CL, SEM-EDS, TA, and OM; additionally, it contains processed data for all the above-mentioned techniques and XRD; finally, in selected cases, it includes interpreted data and analytical reports as concluded by us or presented to us by the responsible scientist(s).

Format names and versions

.csv, .docx, .jpg, .pdf, .spa, .spx, .tiff/tif, .xlsx

Creation dates

May 2022 – December 2024 (part of the SEM analysis was performed in 2025).

Dataset Creators

The following authors have contributed to the creation of the data included in the dataset. Here we briefly summarize their role; in each file of the database, authors are credited with their initials (in parenthesis), if initials are not specified, the owners of the data are the authors of the present paper.

• – Paola Pizzo (PP): sample preparation for all analytical procedures (except for thin and cross-sections); microscopy analysis and interpretation; cathodoluminescence analysis report writing; TA-DSC data collection and interpretation; XRD data collection and first elaboration/interpretation (qualitative); SEM-EDS data acquisition (package 1 and 2) and interpretation (package 2 only); participation in the analytical process of Raman and FTIR.

• – Jan Válek (JV): microscopy data elaboration and interpretation; general supervision.

• – Petr Kozlovcev (PK): cathodoluminescence analysis and data interpretation; general supervision in microscopy data interpretation.

• – Dita Frankeová (DF): supervision of TA data collection; TA-EGA data acquisition; TA data elaboration and interpretation.

• – Alberto Viani (AV): refinement and supervision of XRD data elaboration; quantification of XRD results.

• – Radek Ševčík (RS): quantification of XRD results.

• – Sylwia Svorová-Pawełkowicz (SSP): SEM data acquisition and interpretation (package 1 only).

• – Grażyna Żukowska (GZ): Raman and FTIR analysis report writing; Raman and FTIR spectra collection.

• – Petra Mácová (PM): Raman and FTIR analysis and report writing for samples NPA 27, 28, and 29.

• – Štěpánka Kučková (SK): Organics Analysis data collection and elaboration; supervision in sample preparation; analysis report writing.

Language

English (labels on Raman spectra images are in Polish)

License

CC-BY-NC-ND 4.0, Creative Commons License.

Repository location

https://doi.org/10.57680/asep.0648815

Publication date

28/01/2026.