Non-Destructive Investigation of Historical Enamels Using Portable Alpha-PIXE and XRF Techniques

The study presents a non-destructive compositional investigation of historical enamels from the XI-XII century by combining portable alpha-PIXE and XRF imaging techniques. The research explores the use of these techniques to characterize the glass matrix, identify colorants and opacifiers, and assess the authenticity of the artworks. Experimental setups, parameters, results, and discussions from the 101 Congresso SIF in Roma are detailed in the presentation slides.

• Historical enamels
• Non-destructive analysis
• Portable alpha-PIXE
• XRF imaging
• Art conservation

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1. 1 Non-destructive compositional investigation of historical enamels by combining portable alpha-PIXE and XRF imaging techniques H.C. Santos, C. Caliri, L. Pappalardo, R. Catalano, A. Orlando, F. Rizzo and F.P. Romano 101 Congresso SIF 21-25 seteembre 2015- Roma, Italia

2. 2 101 Congresso SIF Outline 21-25 seteembre 2015- Roma, Italia Samples Experimental Setup portable Alpha-PIXE portable XRF scanner Results and Discussion

3. 3 Samples 101 Congresso SIF 21-25 seteembre 2015 - Roma, Italia Artwork enamels(smalto) on silvered support dated back to XI-XII century A) A. Plaque white, yellow, brown, blue and red; B. Pot white C. Bottle blue and green 8 B) C) Are they forgeries?

4. 4 Approach non-destructive techniques 101 Congresso SIF 21-25 seteembre 2015 - Roma, Italia Alpha-PIXE (Particle Induced X-ray Emission) Characterize the glass matrix high ionization cross section for low Z identify the former, fluxes and stabilizers low penetration XRF (X-ray Fluorescence) Identify the elemental composition of the colorants and opacifier High ionization cross section for medium and high Z

5. 5 101 Congresso SIF 21-25 seteembre 2015 - Roma, Italia Experimental setup

6. 6 Alpha-PIXE 101 Congresso SIF 21-25 seteembre 2015 - Roma, Italia Parameter Value particle of 5 MeV energy (depth 10-20 m) Primary beam Beam size 8 mm diameter obtained by using a collimator SDD Detector 20 mm2active area; 125 eV energy resolution at 5.9 keV Measurement time Measurement geometry 3600 sec. 45 and 90 incidence and detecting angles; 4 mm and 6 mm incidence and detecting distances

7. 7 XRF scanning 101 Congresso SIF - 21-25 seteembre 2015 - Roma, Italia Parameter Value X-ray source 30 W Rh-anode tube Focusing Optic Polycapillary with a focal distance of 1 cm 26 m diameter at the Rh K-lines Beam size at the focus SDD Detector 50 mm2active area; 133 eV energy resolution at 5.9 keV Measurement geometry 45 and 45 incidence and detecting angles Area of scansion 20x20 cm2(max.) 50 m in the scanning micro-XRF Step-size 500 m in the scanning macro-XRF Dwell time 150 ms (including overhead) Measurement time 6.5 h for a 400x400 pixel image

8. 8 101 Congresso SIF 21-25 seteembre 2015 - Roma, Italia Results and Discussion

9. 9 Alpha-PIXE PIXE quantitative data obtained by measuring some enamels decorating artworks Former (matrix of the glass): SiO2 Flux (decrease the melting temperature): Na2O and K2O Stabilizer: CaO Typology: alkali silica glass 101 Congresso SIF 21-25 seteembre 2015 - Roma, Italia Compounds presented higher values compared with ancient glass (XI-XII century) Na2O MgO Al2O3 SiO2 K2O CaO Fe2O3 PbO Enamel (Sample) White (Plaque) 6.6 1.9 1.1 36.8 3.7 2.0 - 38.4 Blue (Plaque) - - 2.4 34.5 3.3 4.8 0.7 24.2 Brown (Plaque) - - 2.4 32.2 4.5 1.4 2.3 27.4 Light blue (Bottle) White (Pot) - - 4.3 - 49.0 34.1 7.9 2.0 1.0 1.4 - 18.8 29.8 9.0 1.8 -

10. 10 XRF scanner - Plaque PyMca -Fast Fit (~2x104 spectra) 101 Congresso SIF 21-25 seteembre 2015 - Roma, Italia Elemental distribution maps Lead less in the red Blue - Co Yellow - Cr(As,Pb) White - As Brown - Mn Red Zn Zn in the red, As in the Yellow/white indicate recent manufacture

11. 11 Red enamel NNMA (PyMca) 101 Congresso SIF 21-25 seteembre 2015 - Roma, Italia ZnS.CdSSe.BaSO4 (cadmium lithopone)

12. 12 101 Congresso SIF 21-25 seteembre 2015 - Roma, Italia XRF scanner: Bottle and Pot Bottle Green Cr Blue Co Pot White As, Pb

13. 13 -XRF scanner: green enamel (Bottle) 101 Congresso SIF 21-25 seteembre 2015 - Roma, Italia Analysis of homogeneity of the green enamel Cr, Ca, K and Pb: homogeneous Fe - inlay Conclusion: Cr was used as colorant agent in the green enamel

14. 14 101 Congresso SIF 21-25 seteembre 2015 - Roma, Italia Conclusions Alpha-PIXE Na, K and Ca characterize the enamels as alkali silica glass and the presence of Pb in high concentration(>20) suggests modern manufacture XRF scanner The elements Cr(green/yellow), Zn[Se, Ba, Cd](red) and the use of As characterize the enamels as modern XVIII-XIX century Reference: Identification of forgeries in historical enamels by combining the non-destructive scanning XRF imaging and alpha-PIXE portable techniques DOI:10.1016/j.microc.2015.08.025

15. 15 101 Congresso SIF 21-25 seteembre 2015 - Roma, Italia Grazie