**5. Conclusions**

The present on-site Raman study of intact Chinese painted enameled porcelains from the 18th century sheds light on the materials (pigments/opacifiers, colorants, glass types of glazes/enamels and body phases) and the technology used during their production. The study also provides a comparative approach for the technical aspects of painted enameled porcelains and contemporaneous enameled metalware regarding the different reigns of the Qing dynasty. The use of the same on-site analytical protocol for these artifact groups is advantageous for comparing the data obtained. The outcomes are significant in terms of the know-how transfer (materials/techniques) from Europe to China by the Jesuit mission at the end of the 17th century.

From the (limited) number of objects studied, it appears that the first innovations were the different types of Naples yellow lead pyrochlore pigments and then the use of European cobalt during the later years of the Kangxi reign for enameled porcelains. Cassiterite appeared first during the same period in certain *cloisonné* enamel wares. The detection of cassiterite traces in a Kangxi enamel is assigned to (the effect of) the use of Sn-rich Naples yellow that induced precipitation of cassiterite. Its addition to adjust the hue is also possible. More artifact studies are needed to clarify this point. Yongzheng enameled objects made use of European recipes for blue, yellow and rose; the opacification with different As phases was identified. Unfortunately, only one metalware piece from the Yongzheng period has been studied [14]. Studies of a larger number of objects are required, in particular to study the technology transfer from the Imperial Palace to the Jingdezhen imperial kilns and to private kilns in Jingdezhen or Guangzhou [27] to really have a statistical view of the number of porcelains on which the lead-based enamels were deposited directly on the body and not on the glazed body [77].

**Author Contributions:** Conceptualization, P.C. and B.Z.; methodology, P.C.; validation, P.C. and B.K.; investigation, P.C.; resources, B.Z., J.-B.C., Y.Y. and V.D.; writing—original draft preparation, P.C.; writing—review and editing, P.C. and B.K.; funding acquisition, P.C. and B.Z. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the French Agence Nationale de la Recherche ANR EnamelFC project—19-CE27-0019-02 and by the Partenariat 'Hubert Curien' PHC-Cai Yuanpei Campus France–China cooperative program.

**Acknowledgments:** M. Gironda from ELIO, XGLab/Bruker is kindly acknowledged for recording the XRF data. C. Gougeon from the Louvre Museum and S. Paronetto from Fontainebleau Castle are acknowledged for their help in the preparation of the measurement campaigns. J. Defretin is acknowledged for providing historical information on some artifacts. Yong Lei and Huawen Liu from the Palace Museum, Department of Analysis and Conservation and Professor Ludovic Bellot-Gurlet from MONARIS (Laboratoire de la MOlécule au Nano-objet: Réactivité, Interaction & Spectroscopies) are kindly acknowledged for many discussions. This work has been conducted under the framework of the Laboratoire International Associé CNRS–Palace Museum TrEnamel and Campus France PHC-Cai Yuanpei programs.

**Conflicts of Interest:** The authors declare no conflict of interest.
