New development on materials and techniques used in the heraldic designs of illuminated Manueline foral charters by multi-analytical methods

In the illuminated foral charters commissioned by D. Manuel I, King of Portugal (1495–1521), heraldry played a prominent role. In this work, royal emblems corresponding to the third heraldic design, applied to the Charter of Couto de Teixedo, are studied by means of EDXRF, SEM–EDS, micro-Raman, micro-FTIR and HPLC–DAD to characterize the materials and techniques used to produce this masterpiece of Portuguese Renaissance. By comparing this data with the results previously obtained in other three charters, this research allows for the first time an accurate insight into the reformed manuscripts production, especially since the illuminated charters under consideration were all investigated on the basis of similar micro-spectroscopic techniques. Inks, metal coatings, pigments, organic dyes, fillers or extenders, and binding media are discussed, and their use enlightened by the politic and legal messages the foral charters had to convey. Parchment analysis allowed us to identify the animal species, and all undertaken processes along its preparation. HPLC–DAD allowed us to differentiate the gums used. CaSO4 was observed in the parchment as a degradation product of CaCO3 used in parchment production in the presence of metal sulfates coming from the ink. Pigments used in the different colors as well as some specific phases for some colors were identified. Silvering and gilding processes, metal caratage and silver oxidation compounds were also objects of the present study. - Highlights: • Complementary analytical techniques using portable XRF and molecular techniques were used for the complete characterization of Portuguese illuminated manuscripts. • A comparison between four Manueline foral charters was undertaken, providing an accurate insight into their heraldic designs and production. • Inks, pigments and some of their specific phases, organic dyes, fillers or extenders, and binding media are discussed. • Silvering and gilding processes, metal caratage and silver oxidation compounds are also objects of the present study. • Their uses are enlightened by the politic and legal messages the foral charters had to convey