The enamels of the first (soft‐paste) European blue‐and‐white porcelains: Rouen, Saint‐Cloud and Paris factories: Complementarity of Raman and X‐ray fluorescence analyses with mobile instruments to identify the cobalt ore

Abstract

The first porcelains made in Europe during the 17th century and the very beginning of the 18th century, that is, before the discovery of kaolin in Saxony (Germany), are rare and technical analyses very limited. In contrast with Meissen Böttger porcelain based on kaolin, these porcelains are made with sand and chymie, like Ottoman fritware. A selection of the blue‐and‐white artefacts belonging to the French national collection is analysed on‐site with mobile portable X‐ray fluorescence (pXRF) and Raman set‐ups: two were assigned to the Poterat Factory at Rouen, three to the Saint‐Cloud Factory and two to the Pavie Factory (Paris). Three types of enamels are identified, lead‐rich (as expected) but also two different lead‐alkaline‐earth alkali enamels, one artefact being covered both with lead‐rich and lead‐poor enamel. The polymerization index deduced from the relative intensity of SiO4 bending and stretching bands indicates different temperatures of firing. Tin is detected in most of the enamels by X‐ray fluorescence (XRF), but cassiterite opacification is only observed for the Pavie Factory artefacts. Arsenic is detected in the blue areas due to the use of European cobalt ores. Comparison of trace and minor elements as well as the type of enamel used suggest that the pot assigned to the Rouen Factory fits much better with a production from the Saint‐Cloud Factory. The two porcelains assigned to the Pavie Factory exhibit similar XRF and Raman signatures that support the attribution based on visual criteria. Combination of the mobile noninvasive XRF and Raman instruments may allow the reliable classification of artefacts on‐site. Raman scattering is very efficient to detect (on‐site) As‐based minor phases.

The Technology Transfer from Europe to China in the 17th–18th Centuries: Non-Invasive On-Site XRF and Raman Analyses of Chinese Qing Dynasty Enameled Masterpieces Made Using European Ingredients/Recipes

“…On the contrary, the painted blue enamel of the ewer strikingly shows a distinctive ~820 cm −1 peak with a shoulder at 788 cm −1 ( Figure 10 a,b,d) which is characteristic of the As-O symmetrical stretching mode in a lead arsenate phase. This feature is particularly assigned to lead–potassium–calcium arsenate with an apatite structure [ 52 , 53 , 61 , 63 , 74 , 91 ] which is formed by the reaction of lead, potassium and calcium coming from the enamel matrix with arsenic coming from the cobalt source [ 10 , 46 , 62 , 74 ]. In some cases, the As-O mode is of a larger intensity ( Figure 10 c), which indicates very small apatite grains or the formation of another kind of As-based phase (As-feldspar?)…”

“…Raman analyses were carried out at the museum exhibition room with a mobile HE532 Raman set-up (HORIBA Scientific Jobin-Yvon, Longjumeau, France) as extensively described in the references [ 45 , 46 , 52 , 53 ]. For each colored area in the objects, at least three Raman spectra were recorded to obtain the representativeness of the collected data on a statistical basis.…”

“…For several years, we have been developing procedures and models allowing the implementation and interpretation of the results obtained by mobile Raman microscopy and X-ray fluorescence devices [ 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 ], specifically for the identification of coloring agents and silicate matrices of the glassy materials such as the enamels. Analyses were thus carried out on the collections of enameled objects (glass, metal or porcelain) produced in France and China between the 17th and the 19th century [ 10 , 36 , 38 , 39 , 44 , 45 , 46 , 52 , 53 ], allowing us to identify the objects most representative of the technological change for the period mentioned.…”

High‐fired early English porcelains of the ‘A’‐marked group, east London (c. 1744): A Raman spectroscopy and electron microscopy compositional study

“…Colomban et al [50] reported that 17th century European cobalt ores and thus smalt are rich in arsenic and which lead to the precipitation of lead arsenate apatite by its reaction with leadbased glazes and enamels. [83,84] They stated that the peak maximum can shift from $815 to 830 cm À1 , and band broadening may be due to the presence of variable arsenic phases with differing levels of incorporated elements. Thus, the Raman signature with peaks at 782 and 818 cm À1 is typical of the precipitation of an apatite with a formulation close to Na 0.4 K 0.1 Ca 0.5 Pb 4 (AsO 4 ) 3 .…”

Tribute to Derek Long: An instant snapshot of the development of Raman spectroscopy and its application in the fields of instrumentation and methodology, solid‐state materials, cultural heritage, DFT modeling and applications in biology, microbiology, and medicine

“…The contribution by Colomban et al ( The Enamels of the First [Soft‐paste] European Blue‐and‐white Porcelains: Rouen, Saint‐Cloud and Paris Factories: Complementarity of Raman and X‐ray Fluorescence analyses with Mobile Instruments to identify the cobalt ore , Sorbonne Université, France) [ 31 ] studies the first porcelains made in Europe during the 17th century and the very beginning of the 18th century made with sand and chymie , that is, before the discovery of kaolin in Saxony (Germany). Artifacts are analyzed on‐site with mobile portable X‐ray fluorescence (pXRF) and Raman set‐ups.…”