Table 3 Summary of the major findings on the materials of the Ruby Slippers found through analysis by µ-XRF and µ-FTIR, with notes on PLM and HPLC–DAD–MS findings
From: Materials characterization of the Ruby Slippers from the 1939 classic film, The Wizard of Oz
Materials analyzed | µ-XRF | µ-FTIR | Materials identification and notes |
|---|---|---|---|
Sequins | |||
Detached sequin 1 | Major: Zn, S, Ca, Cl Minor: Fe, Ag Trace: P? | Protein core (3306, 1644, 1539 cm−1) Cellulose nitrate coating (1644, 1278, 1065, 841 cm−1) | Protein-based core with red cellulose nitrate coating A thin silver layer between the core and coating. The main red colorant in the cellulose nitrate coating was identified as Rhodamine B by HPLC-DAD-MS. This finding explains the chlorine detected by µ-XRF |
Detached sequin 2 | Protein core (3304, 1644, 1543, 1240 cm−1) Cellulose nitrate coating (1650, 1280, 1162, 1073, 841, and 753 cm−1) | Protein-based core with red cellulose nitrate coating (See “Adhesives”—for identification of adhesive residue on detached sequin 2) | |
Attached sequin, p.l. side near heel, p.l shoe | Major: Cl, Zn Minor: S, Ca, Fe Trace: K, P? | Protein core (1644, 1543, 1240, 3304 cm−1) Cellulose nitrate coating (1650, 1280, 1073, 841 cm−1) | Protein-based core with red cellulose nitrate coating. Red colorant could not be identified by FTIR |
Prong settings | |||
Prong, right side near center, p.r. shoe | Major: Cu, Zn Minor: S, Fe, Ag Trace: Cl, Mn, Hg, Ca | Brass | |
Prong with red coating, p.r. shoe | Major: Cu, Zn Minor: Fe Trace: Cl, Mn, Ca, Ti, Ag, Pb? | Cellulose nitrate coating (1649, 1281, 1072, 845, 751 cm−1) | Brass Red coating is cellulose nitrate based The red colorant could not be characterized. |
Prong, p.l. shoe | Major: Cu, Zn Minor: S, Fe, Ag Trace: Cl, Mn, Ca | Brass | |
Prong, p.l. shoe | Major: Cu, Zn Minor: Fe, Pb, Se, Ca, K, Si Trace: Ba, Mn | Brass Note that minor and trace elements in µ-XRF data probably originate from the nearby red stone held by the prong setting | |
Beads and rhinestones | |||
Large red bead, p.r. side, p.r. shoe | Major: Zn, Si, K Minor: Fe, Se Trace: As, Cd?, Rb? | Potash-silica glass (type 1, Selenium ruby glass) | |
Red bugle bead, p.l. side, p.r. shoe | Major: Zn, Si, K, Ca Minor: Fe, Se Trace: Cu, As, Cd, Rb | Potash–lime–silica glass (type 2, Selenium ruby glass) | |
Red stone, p.l. side, p.r. shoe | Major: Zn, Si, K, Ca Minor: Fe, As, Se Trace: Rb, Ba?, Cd?, Pb? | Potash–lime–silica glass (type 2, Selenium ruby glass) | |
Red stone. upper p.l. corner, p.r. shoe | Major: Zn, Si, K, Ca Minor: Fe, As, Se Trace: Ba, Cu, Rb, Pb? | Potash–lime–silica glass (type 2, Selenium ruby glass) | |
Red stone, upper p.r. corner, p.r. shoe | Major: Zn, Si, K, Ca Minor: Fe, As, Se Trace: Cu?, Rb? | Potash–lime–silica glass (type 2, Selenium ruby glass) | |
Colorless stone, p.l. upper corner, p.r. shoe | Major: Pb, K, Ca Minor: Si, Fe, Zn, As, Cu, Ba Trace: – | Lead–potash–lime–silica glass (type 3) | |
Red coating on colorless stone, upper p.r. corner, p.r. shoe | Major: Pb, K, Ca Minor: Si, Ba, Fe, Cu, Zn Trace: – | Cellulose nitrate (1649, 1281, 1072, 845, 751 cm−1) | Lead–potash–lime–silica glass (type 3) The red coating is cellulose nitrate based The red colorant could not be characterized |
Large red bead, p.r. side, p.l. shoe | Major: Si, K, Zn Minor: Cd, Fe, Se Trace: Ca As/Pb, Rb, Ti? | Potash–silica glass (type 1, Selenium ruby glass) | |
Large red central bead, p.l. shoe | Major: Si, K, Ca, Zn Minor: As, Ba, Se, Fe Trace: Cd, Mn, Rb, Pb? | Potash–lime–silica glass (type 2, Selenium ruby glass) | |
Red bugle bead from p.r. side, p.l. shoe | Major: Zn, Si, K, Ca Minor: Se, Cd Trace: Fe, As/Pb | Potash–lime–silica glass (type 2, Selenium ruby glass) | |
Paints | |||
Red paint on sole near arch, p.r. shoe | Major: Cd, Ba, Se Minor: S Trace: Fe, Cu, Zn, As/Pb, Sr | Cellulose nitrate (1659, 1280, 842 cm−1), alkyd (1728, 2934, 2870 cm−1), barium sulfate (1117, 1074, 983 cm−1) | Cadmium red lithopone pigment; cellulose nitrate-alkyd formulation |
Red paint on sole, near orange felt, p.r. shoe | Major: Ba, Fe, Se Minor: S, Cd, Ca Trace: Cu, Zn, As/Pb | Cadmium red lithopone pigment with possibly iron oxide | |
Red paint on sole, near arch, p.l. shoe | Major: Cd, Ba, Se Minor: S, Fe, Cu, Zn Trace: Cu, Sr, As/Pb Sr | Cellulose nitrate (1659, 1280, 842 cm−1), alkyd (1728, 2934, 2870 cm−1), barium sulfate (1117, 1074, 983 cm−1) | Cadmium red lithopone pigment; cellulose nitrate-alkyd formulation |
Red paint on sole, near orange felt, p.l. shoe | Major: Cd, Ba, Se Minor: S, Fe, Zn Trace: Cu, As/Pb, Sr | Cadmium red lithopone pigment | |
Adhesives | |||
Adhesive on detached sequin 2 | Polyvinyl acetate (3541, 2926, 1736, 1373, 1240, 1123, 1022, 947, 793 cm−1) | Polyvinyl acetate This material on detached sequin 2 is likely contamination by an adhesive residue | |
Outsole adhesive (between sole and shoe), p.r. shoe | Natural resin (2969, 2935, 1716, 1453, 1379 cm−1) | Natural resin | |
Adhesive between inner and outer orange felt, p.r. shoe | Polyvinyl acetate (1739, 1434, 1373, 1242 cm−1) | Polyvinyl acetate | |
Clear, soft adhesive on heel, between sole and shoe, p.r. shoe | Poly(ethyl acrylate) (2980, 2937, 2876, 1734, 1448, 1380, 1236, 1169, 1096, 854, 787, 755 cm−1) | Poly(ethyl acrylate) | |
Glossy adhesive near sole, p.r. shoe | Cellulose nitrate (1650, 1277, 1069, 842 cm−1) | Cellulose nitrate | |
Glossy adhesive near sole, p.l. shoe | Cellulose nitrate (1650, 1277, 1069, 842 cm−1) | Cellulose nitrate | |
Adhesive between orange felt and sole, p.l. shoe | Polyvinyl acetate (1739, 1434, 1373, 1242 cm−1) | Polyvinyl acetate | |
Fibers | |||
Sequin thread, p.r. shoe | Cellulose (3342, 2899, 116, 1115 cm−1) | Cotton (identified by PLM) | |
Red netting thread, p.r. shoe | Protein (1645, 1519, 1234, 3298 cm−1) | Silk, red dyed (identified by PLM). Red dye could not be characterized | |
Red thread holding netting to shoe, p.r. shoe | Protein (1645, 1519, 1234, 3298 cm−1) | Silk, red dyed (identified by PLM). Red dye could not be characterized | |
Orange felt on central sole area, p.r. shoe | Major: S, Fe, Zn Minor: Ca, Mn, Cu, Pb, Ba Trace: Cr?, Zr? | Protein (1655, 1530, 1235, 3302 cm−1) | Wool, orange dyed (identified by PLM) Dye component could not be characterized |
Structural shoe fabric, p.r. shoe | Cotton, possibly mercerized (identified by PLM) | ||
Sole near arch, p.r. shoe | Leather (identified by PLM) | ||
Bow support thread, left, p.r. shoe | Cotton (identified by PLM) | ||
Red thread holding netting to shoe, p.l. shoe | Protein (1645, 1519, 1234, 3298 cm−1) | Silk, dyed red (identified by PLM). Red dye could not be characterized | |
Sequin thread, p.l. shoe | Cellulose (3342, 2899, 1161, 1115 cm−1) | Cotton (identified by PLM) | |
Orange felt, near edge, p.l. shoe | Major: S, Fe, Zn Minor: Ca, Ba, Mn, Cu, K Trace: Pb, Ti? | Protein (1655, 1530, 1235, 3302 cm−1) (thick fiber) | Wool, dyed orange; undyed wool, cotton, other fibers present in minor amounts (identified by PLM). Dye could not be characterized |
Decorative silk faille shoe fabric, p.l. shoe | Silk, red dyed (identified by PLM). Dye could not be characterized. | ||
Red netting thread, p.l. shoe | Protein (1645, 1519, 1234, 3298 cm−1) | Silk, red dyed (identified by PLM) | |
Fiber materials from heel, p.l. shoe | Cellulose (3347, 2897, 1161, 1113 cm−1) Natural resin (2967, 2935, 1712, 1453 and 1376 cm−1) | Cellulose-based fibers coated with natural resin | |
Heel materials | |||
Brown heel material, p.r. shoe | Major: Fe, Zn Minor: S, K, Ca, Ba, Pb Trace: Si | No identification Some elements found by may be due to nail corrosion | |
Heel nail, p.r. shoe | Major: Fe Minor: Ca, Mn Trace: S, Zn, Cu, Si, K, Ba, Cr | Iron or steel | |
Heel nail, p.l. shoe | Major: Fe, Zn Minor: S, Ca Trace: Mn | Galvanized iron or steel | |