Appendix: Silver Alloy Analysis by X-ray Fluorescence Spectroscopy

The alloy composition of the silver objects in this catalogue has been characterized using X-ray fluorescence spectroscopy (XRF) (Table 1). This analysis was conducted to assist with the overall technical study of the works in this catalogue, particularly to identify potential alterations and restorations. XRF is a rapid, multielemental, and completely nondestructive analytical technique and is thus well suited to the study of works of art. XRF is a surface-analysis technique that measures the composition of the silver artifacts to a depth of only several tens of microns. Therefore, the XRF results may not represent the bulk alloy if silver-enriched or -depleted layers are present on the surface of the metal. Repeated annealing and pickling of silver, as commonly occurs when raising hollow forms from sheet, is known to result in silver enrichment of several tens of microns at the surface, though repeated polishing over time can remove the enriched layer.¹ One method for detecting surface enrichment or depletion is to evaluate the ratio of silver L and K emission lines in an XRF spectrum.² This method was used to flag some measurements as potentially nonrepresentative of the bulk. Results in the table with excessively high or low silver L-to-K (L/K) ratios are marked with * and ** respectively.

Table 1 XRF results¹ from the technical examination of objects in this catalogue

Sample	n=2	Co	Cu	Zn	Ag	Cd	Sn	Sb	Au	Pb	Bi	Total3		Instrument
82.DG.17 Coat of arms (burnished lobe)	4	0.00	1.3	0.0	98.4	0.01	0.01	0.03	0.02	0.3	0.02	100.1		Bruker Tracer III-SD
82.DG.17 Cartouche, proper right top acanthus spiral	3	0.00	3.1	0.1	96.6	0.01	0.11	0.04	0.01	0.2	0.00	100.1		Bruker Tracer III-SD
82.DG.17 Spigot, fleur-de-lys	1	0.00	5.0	0.1	94.4	0.01	0.01	0.02	0.09	0.3	0.03	100.0		Bruker Tracer III-SD
82.DG.17 Lid, polished raised sheet	3	0.00	5.1	0.0	95.0	0.01	−0.03	0.00	0.01	0.1	0.01	100.2		Bruker Tracer III-SD
82.DG.17 Lion mask, nose	3	0.00	3.5	0.1	96.2	0.00	0.11	0.00	0.01	0.1	0.00	100.0		Bruker Tracer III-SD
82.DG.17 Body, raised sheet, proper left	3	0.00	2.6	0.0	97.0	0.00	0.03	0.01	0.07	0.3	0.02	100.1		Bruker Tracer III-SD
82.DG.17 Handle, proper left	3	0.00	3.2	0.2	96.1	0.00	0.03	0.00	0.11	0.4	0.02	100.0		Bruker Tracer III-SD
82.DG.17 Skirt, lower body, proper left maker's stamp	3	0.00	2.0	0.0	97.9	0.02	0.05	0.02	0.02	0.1	0.00	100.1		Bruker Tracer III-SD
82.DG.17 Putto, shoulder blade, proper left	3	0.00	3.8	0.0	95.9	0.01	0.14	0.04	0.04	0.2	0.01	100.1		Bruker Tracer III-SD
82.DG.17 Repair patch, upper acanthus	3	0.00	3.9	0.1	96.0	0.00	0.01	0.00	0.01	0.1	0.01	100.1		Bruker Tracer III-SD
82.DG.17 Base, front side, T-shaped geometric motif	3	0.00	5.7	0.2	93.8	0.01	0.02	0.01	0.08	0.2	0.01	100.0		Bruker Tracer III-SD
82.DG.17 Rim of neck, gadroons	4	0.00	3.1	0.0	96.5	0.01	0.08	0.02	0.08	0.2	0.01	100.1		Bruker Tracer III-SD
82.DG.17 Flared foot, polished raised sheet	4	0.00	5.5	0.1	93.9	0.00	0.10	0.01	0.08	0.3	0.03	100.0		Bruker Tracer III-SD
82.DG.17 Neck, burnished flute	6	0.00	0.9	0.0	98.7	0.01	0.05	0.02	0.08	0.3	0.02	100.1		Bruker Tracer III-SD
82.DG.17 Base, proper left, top surface	4	0.00	5.5	0.0	94.0	0.02	0.09	0.02	0.08	0.3	0.01	100.1		Bruker Tracer III-SD
82.DG.17 Cartouche, auricular mask	5	0.00	1.9	0.0	97.8	0.01	0.13	0.03	0.01	0.2	0.00	100.1		Bruker Tracer III-SD
82.DG.17 Repair patch, spot 2	3	0.00	4.3	0.0	95.8	0.00	0.00	0.01	0.01	0.1	0.01	100.2		Bruker Tracer III-SD
82.DG.17 Putto, proper left thigh	3	0.00	4.4	0.1	95.3	0.00	0.08	0.02	0.04	0.2	0.01	100.1		Bruker Tracer III-SD
82.DG.17 Body, raised sheet, proper right	3	0.00	1.7	0.0	98.0	0.01	−0.03	0.02	0.07	0.3	0.02	100.1		Bruker Tracer III-SD
82.DG.17 Waterfowl tap	3	0.00	2.6	0.0	97.1	0.01	0.07	0.01	0.14	0.1	0.03	100.2	*	Bruker Tracer III-SD
71.DG.76.a Bowl, cartouche	1	0.00	4.9	0.2	94.3	0.01	0.04	0.01	0.22	0.2	0.01	100.0		Bruker Tracer 5i
71.DG.76.a Bowl, exterior	3	0.00	2.8	0.0	97.1	0.00	−0.02	0.01	0.14	0.1	0.00	100.1		Bruker Tracer 5i
71.DG.76.a Bowl, handle	2	0.01	2.8	0.0	96.8	0.01	0.07	0.01	0.19	0.1	0.00	100.1		Bruker Tracer 5i
71.DG.76.b Basket, exterior, olive	1	0.01	3.7	0.2	95.7	0.00	0.10	0.01	0.19	0.2	0.00	100.0		Bruker Tracer 5i
71.DG.76.b Stand, bottom	1	0.00	2.5	0.0	97.2	0.00	0.02	0.02	0.16	0.2	0.00	100.1		Bruker Tracer 5i
71.DG.76.b Stand, bottom, wave	1	0.00	1.6	0.0	98.1	0.01	0.02	0.01	0.17	0.1	0.00	100.1		Bruker Tracer 5i
71.DG.76.b Stand, top	1	0.00	3.0	0.1	96.6	0.01	0.04	0.01	0.16	0.2	0.00	100.1		Bruker Tracer 5i
71.DG.78 Bottom	1	0.00	1.6	0.0	98.3	0.00	−0.02	0.01	0.07	0.1	0.03	100.1		Bruker Tracer 5i
71.DG.78 Foot, bottom	1	0.01	3.0	0.3	96.2	−0.01	0.20	0.01	0.10	0.2	0.01	99.9		Bruker Tracer 5i
71.DG.78 Rim, bottom	1	0.00	3.2	0.0	96.5	−0.01	0.10	0.02	0.09	0.1	0.02	100.1		Bruker Tracer 5i
71.DG.78 Rim, top	1	0.01	3.1	0.0	96.6	0.00	0.13	0.01	0.09	0.1	0.01	100.1		Bruker Tracer 5i
71.DG.78 Bottom, ball of solder(?)	1	0.00	2.8	0.0	97.1	0.00	−0.04	0.01	0.08	0.1	0.02	100.1		Bruker Tracer 5i
71.DG.78 Top, burnished	1	0.00	3.9	0.0	95.9	0.00	0.08	0.01	0.08	0.1	0.03	100.1		Bruker Tracer 5i
82.DG.12.1.b Tureen side, exterior (polished)	1	0.00	3.0	0.1	96.0	0.00	0.08	0.01	0.13	0.6	0.00	99.9		Bruker Tracer 5i
82.DG.12.1.b Tureen interior, base	1	0.00	2.0	0.0	97.7	0.00	0.07	0.01	0.15	0.1	0.01	100.1		Bruker Tracer 5i
82.DG.12.1.b Tureen, coronet on armorial	1	0.00	1.5	0.0	98.3	−0.01	0.02	0.02	0.09	0.1	0.01	100.1		Bruker Tracer 5i
82.DG.12.1.b Tureen, boar, snout	1	0.00	3.7	0.0	96.0	0.01	0.15	0.01	0.09	0.1	0.01	100.1		Bruker Tracer 5i
82.DG.12.1.b Tureen, armorial, polished lobe	1	0.00	3.7	0.0	96.2	0.00	−0.03	0.01	0.10	0.1	0.01	100.1		Bruker Tracer 5i
82.DG.13.1.a Lid, cauliflower	1	0.00	1.6	0.0	98.3	0.00	−0.03	0.01	0.12	0.1	0.01	100.1		Bruker Tracer 5i
82.DG.13.1.a Lid, crab pincer	1	0.00	3.3	0.0	96.6	−0.01	0.03	0.01	0.10	0.1	0.02	100.1		Bruker Tracer 5i
82.DG.13.1.a Lid, interior	1	0.00	0.6	0.0	99.2	0.00	−0.05	0.01	0.16	0.1	0.00	100.1		Bruker Tracer 5i
82.DG.13.1.a Lid, exterior	1	0.00	3.3	0.1	96.2	0.01	0.12	0.02	0.15	0.2	0.01	100.1		Bruker Tracer 5i
82.DG.13.1.b Liner, exterior bottom	1	0.00	2.2	0.1	97.2	0.00	0.11	0.01	0.20	0.2	0.00	100.0		Bruker Tracer 5i
82.DG.13.1.b Liner, interior rim	1	0.01	2.6	0.1	96.8	0.01	0.16	0.01	0.23	0.1	0.00	100.0		Bruker Tracer 5i
82.DG.13.1.c Tureen, exterior bottom and side	2	0.00	2.9	0.1	96.7	0.01	0.07	0.01	0.16	0.2	0.01	100.1		Bruker Tracer 5i
82.DG.13.1.c Tureen, interior rim	1	0.00	1.6	0.0	98.0	0.02	0.08	0.01	0.17	0.2	0.01	100.0		Bruker Tracer 5i
82.DG.13.1.c Tureen, interior bottom	1	0.01	0.2	0.0	99.3	0.01	0.13	0.01	0.20	0.1	0.00	100.0		Bruker Tracer 5i
82.DG.13.1.c Tureen, foot	1	0.00	2.9	0.1	96.6	0.00	0.05	0.01	0.19	0.2	0.01	100.1		Bruker Tracer 5i
82.DG.13.1.c Tureen, handle	1	0.00	3.4	0.1	96.1	0.01	0.08	0.01	0.14	0.2	0.02	100.1		Bruker Tracer 5i
82.DG.13.1.d Stand, back	1	0.00	3.8	0.0	95.9	0.00	0.06	0.01	0.19	0.1	0.01	100.1		Bruker Tracer 5i
82.DG.13.1.d Stand, front	1	0.00	3.9	0.0	95.9	0.00	0.00	0.01	0.19	0.2	0.01	100.1		Bruker Tracer 5i
82.DG.13.2.a Lid, cauliflower	1	0.00	3.3	0.1	96.2	0.01	0.02	0.01	0.17	0.2	0.01	100.1	**	Bruker Tracer 5i
82.DG.13.2.a Lid, crab pincer	1	0.00	2.6	0.0	97.3	−0.01	0.04	0.01	0.11	0.1	0.02	100.1		Bruker Tracer 5i
82.DG.13.2.a Lid, interior	1	0.00	0.5	0.0	99.2	0.00	−0.04	0.01	0.20	0.1	0.01	100.1		Bruker Tracer 5i
82.DG.13.2.a Lid, exterior	1	0.00	3.3	0.1	96.2	0.01	0.02	0.01	0.17	0.2	0.01	100.1	**	Bruker Tracer 5i
82.DG.13.2.b Liner, exterior bottom	1	0.00	3.1	0.1	96.5	0.01	0.00	0.01	0.17	0.2	0.00	100.1		Bruker Tracer 5i
82.DG.13.2.b Liner, interior rim	1	0.00	3.4	0.0	96.2	−0.01	0.03	0.01	0.18	0.2	0.00	100.1	*	Bruker Tracer 5i
82.DG.13.2.c Tureen, exterior bottom (polished)	1	0.00	2.5	0.0	97.3	0.00	0.08	0.01	0.04	0.1	0.02	100.1		Bruker Tracer 5i
82.DG.13.2.c Tureen, exterior side	1	0.00	4.4	0.0	95.5	0.00	0.03	0.01	0.05	0.1	0.02	100.1		Bruker Tracer 5i
82.DG.13.2.c Tureen, interior rim	1	0.00	0.9	0.0	99.0	0.00	0.01	0.01	0.06	0.1	0.01	100.1		Bruker Tracer 5i
82.DG.13.2.c Tureen, interior bottom	1	0.00	0.5	0.0	99.4	0.01	0.04	0.02	0.06	0.1	0.01	100.0		Bruker Tracer 5i
82.DG.13.2.c Tureen, foot	1	0.00	2.0	0.0	97.7	0.00	0.09	0.01	0.19	0.1	0.01	100.1		Bruker Tracer 5i
82.DG.13.2.c Tureen, handle	1	0.00	3.8	0.1	95.7	0.00	0.11	0.01	0.17	0.2	0.02	100.1		Bruker Tracer 5i
82.DG.13.2.d Stand, back	1	0.00	4.0	0.0	95.8	−0.01	0.04	0.01	0.20	0.2	0.01	100.2		Bruker Tracer 5i
82.DG.13.2.d Stand, front	1	0.00	3.3	0.0	96.6	0.01	−0.04	0.01	0.19	0.1	0.01	100.2		Bruker Tracer 5i
84.DG.744.1.a Lid, basket	1	0.00	1.1	0.1	98.4	0.00	−0.03	0.01	0.29	0.2	0.00	100.0		Bruker Tracer 5i
84.DG.744.1.a Lid, flower	1	0.01	1.3	0.0	98.4	−0.01	−0.02	0.02	0.24	0.2	0.00	100.1	**	Bruker Tracer 5i
84.DG.744.1.b Vessel, exterior	1	0.00	2.4	0.0	96.9	0.01	0.12	0.01	0.22	0.4	0.02	100.0		Bruker Tracer 5i
84.DG.744.1.b Vessel, exterior base, side	1	0.01	1.7	0.0	97.6	−0.01	−0.03	0.01	0.24	0.5	0.00	100.0		Bruker Tracer 5i
84.DG.744.1.b Vessel, flower	1	0.00	1.0	0.0	98.7	−0.01	−0.01	0.01	0.24	0.2	0.01	100.1		Bruker Tracer 5i
84.DG.744.1.b Vessel, exterior textured surface	1	0.00	3.6	0.0	96.0	−0.01	0.03	0.01	0.19	0.2	0.01	100.1		Bruker Tracer 5i
84.DG.744.2.a Lid, basket	1	0.00	1.3	0.0	98.3	0.01	0.08	0.01	0.25	0.1	0.00	100.1		Bruker Tracer 5i
84.DG.744.2.a Lid, flower	1	0.01	1.1	0.0	98.5	0.01	0.08	0.01	0.27	0.1	0.00	100.1	**	Bruker Tracer 5i
84.DG.744.2.b Vessel, exterior	1	0.00	1.3	0.2	97.9	0.00	0.03	0.01	0.21	0.3	0.01	99.9		Bruker Tracer 5i
84.DG.744.2.b Vessel, exterior base, side	1	0.00	3.1	0.0	96.2	−0.01	0.07	0.01	0.28	0.3	0.00	100.1		Bruker Tracer 5i
84.DG.744.2.b Vessel, flower	2	0.00	1.3	0.0	98.2	0.00	0.07	0.01	0.18	0.2	0.01	100.0		Bruker Tracer 5i
2005.43 Rabbit	1	0.00	2.6	0.0	97.1	0.01	0.09	0.01	0.17	0.1	0.01	100.1		Bruker Tracer 5i
2005.43 Cauliflower	1	0.02	1.3	0.0	98.3	0.00	0.18	0.01	0.14	0.1	0.00	100.1	**	Bruker Tracer 5i
2005.43 Base, front	1	0.00	3.7	0.0	96.0	0.00	0.03	0.02	0.14	0.2	0.02	100.1		Bruker Tracer 5i
2005.43 Ground (repoussé)	1	0.00	1.3	0.0	98.3	0.01	0.04	0.01	0.18	0.2	0.01	100.1		Bruker Tracer 5i
2005.43 Rim, inside	1	0.00	3.1	0.1	96.6	0.00	0.01	0.02	0.12	0.1	0.03	100.1		Bruker Tracer 5i
2005.43 Snipe, proper right leg	1	0.03	2.3	0.0	97.3	0.00	0.11	0.01	0.16	0.1	0.00	100.1	**	Bruker Tracer 5i
2005.43 Solder pallion, underside	1	0.00	1.5	0.3	98.1	0.00	0.00	0.01	0.04	0.1	0.01	99.9		Bruker Tracer 5i
84.DG.42.2 Putti thigh	1	0.00	2.4	0.0	97.2	0.00	0.03	0.02	0.13	0.1	0.01	100.0		Bruker Artax
84.DG.42.2 Putti back	1	0.00	4.1	0.1	95.6	0.00	0.05	0.02	0.09	0.2	0.02	100.1	*	Bruker Artax
84.DG.42.1 Putti thigh	1	0.00	3.7	0.0	96.0	0.01	0.08	0.02	0.08	0.1	0.01	100.1		Bruker Artax
84.DG.42.1 Putti back	1	0.00	4.4	0.1	95.3	0.00	0.01	0.02	0.09	0.2	0.02	100.0		Bruker Artax
88.DH.127.2 Vessel, exterior tie wrap	1	0.01	3.9	0.0	95.7	0.01	0.05	0.01	0.11	0.3	0.03	100.0		Bruker Artax
88.DH.127.2 Vessel, catch-latch rim	1	0.00	1.1	0.1	98.4	0.01	0.09	0.01	0.28	0.1	0.01	100.1		Bruker Artax
88.DH.127.2 Vessel, ring attached to rim	1	0.00	1.0	0.1	98.6	0.02	0.37	0.04	0.29	0.2	0.01	100.5		Bruker Artax
88.DH.127.2 Vessel, exterior bottom	1	0.00	0.7	0.0	99.0	0.00	0.02	0.01	0.15	0.1	0.01	100.0		Bruker Artax
88.DH.127.2 Vessel, threaded rod bottom	1	0.00	1.8	0.1	97.6	0.01	0.11	0.02	0.26	0.2	0.01	100.1		Bruker Artax
88.DH.127.2 Lid, flower petal	1	0.00	1.0	0.0	98.7	0.01	0.08	0.01	0.11	0.2	0.02	100.1		Bruker Artax
88.DH.127.2 Lid, catch-latch rim	1	0.00	1.1	0.1	98.3	0.00	0.11	0.02	0.26	0.2	0.01	100.1		Bruker Artax
88.DH.127.2 Lid, exterior side	1	0.00	3.8	0.0	95.7	0.01	0.01	0.01	0.12	0.3	0.03	100.0		Bruker Artax
Errors (95% C.I.4)		0.01	0.7	0.1	2.3	0.08	0.04	0.03	0.02	0.2	0.02			Bruker Tracer 5i
		0.01	0.6	0.2	1.7	0.04	0.05	0.03	0.03	0.2	0.03			Bruker Artax
		0.02	0.6	0.1	1.7	0.08	0.04	0.04	0.02	0.2	0.03			Bruker Tracer III-SD

*

Silver L/K ratio elevated.

**

Silver L/K ratio depressed.

1.

Values in gray are below the detection limit (defined as “critical value” at 95-percent confidence per Kadachi and Al-Eshaikh 2012).

2.

Number of measurements taken at each site.

3.

Quantitative results have not been normalized; totals do not always add up to exactly 100 percent.

4.

A 95-percent confidence interval represents the range above and below the estimated value within which the true value is likely to fall, with a confidence of 95 percent. See additional discussion above.

Three different XRF instruments were used to analyze the objects in this catalogue, over a period of several years. The operating parameters for each instrument were as follows:

1. Bruker-Artax: This instrument uses a chromium-tube anode; the live acquisition time for each spectrum was 250 seconds; voltage was 50 KeV; amperage was 600 µA. A 315 µm–thick aluminum beam filter was used and the tube was fitted with a 1.5 mm–diameter collimator.

2. Bruker-Tracer 5i: This instrument uses a rhodium-tube anode; the real acquisition time was 60 seconds; voltage was 50 KeV; amperage was 35 µA. A 38 µm–thick aluminum beam filter was used and the tube was fitted with a 3 mm–diameter collimator.

3. Bruker Tracer III-SD: This instrument uses a rhodium-tube anode; the real acquisition time was 60 seconds; voltage was 40 KeV; amperage was 15 µA. A 300 µm–thick aluminum and a 25 µm titanium beam filter were used, and the analytical spot size was approximately 8 mm in diameter.

Substantial effort was made to calibrate each instrument rigorously so that the results are both accurate and comparable. The calibration procedure for each instrument followed the CHARMed PyMca protocol using 11 silver-alloy reference standards.³ Seven of these standards were manufactured by MBH Analytical (designated 133X AGQ1, 133X AGQ2, 133X AGQ3, 132X AGB 85B, 133X AGA1, 133X AGA2, and 133X AGA3), three were in-house standards from the Getty Conservation Institute (designated GCI-silver-A, GCI-silver-B, and GCI-silver-C), and one was a pure silver sample manufactured by Premion.

The uncertainties (errors) in the measurements reported here are averages. More precise estimates of uncertainty have been calculated individually for each measurement based on the “error of prediction” model.⁴ Complete data with errors are available upon request to the Department of Decorative Arts and Sculpture conservation. Detection limits associated with the final estimates were determined based on the standard formula for the critical value, or C.V., at the 95 percent confidence level.⁵

Where gilded surfaces were analyzed with XRF, quantitative results for the base alloy could not be calculated. Spectra from gilded surfaces were evaluated to determine whether mercury was also present along with the gold, as would be expected if the gold had been applied by amalgam gilding. Where mercury peaks were clearly seen in the spectra (this was true for all analyses of gilding), an estimate was made of the amount of mercury remaining in the gold, using standardless quantification results for both gold and mercury as generated by PyMca software (see Table 2).

Table 2 XRF results for gilded surfaces, showing the amount of mercury remaining in the gold

Sample	Au-L	Hg-L	Estimated wt.% Hg in Au
71.DG.77.a Lid, exterior	14.5	0.18	1.2
71.DG.77.a Lid, interior	13.3	0.85	6.4
71.DG.77.b Bowl, interior	18.4	1.03	5.6
71.DG.77.b Bowl, exterior	17.4	0.26	1.5
71.DG.77.b Handle, proper right underside	22.5	0.55	2.5
71.DG.77.b Handle, proper left underside	22.1	0.55	2.5
71.DG.76.1 Sauceboat, interior	34.1	0.87	2.5

1. Mass and Matsen 2012a. ↩︎

2. Borges et al. 2018. ↩︎

3. Heginbotham and Solé 2017; Heginbotham et al. 2019. ↩︎

4. Heginbotham and Solé 2017. ↩︎

5. Kadachi and Al-Eshaikh 2012. ↩︎