| Original Message: Re: Status of Scientific Approach |
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Two commom approaches are EDX (electron dispersive xray) and SEM (scanning electron microscopy); the former provides a qualitative elemental analysis, and the latter provides detail surface morphology. Two others are ICP (Inductively Coupled Plasma Emission Spectrophotometry)--providing a quantitative elemental analysis, and Auger spectrosopy-- providing localized surface quantitative analysis. FTIR (Fourier Transform Infrared Spectrometry) is also a great tool for discerning between various organic surface constituents - resins, epoxys, polyamides. About three years ago, I began to notice a flurry of what were termed tabular Roman face beads (typically 5 to 10 mm diameter, perhaps a little larger). Some of the yellow colors just seemed (to me) too vivid. I spent a few weeks running elemental and compound scans on the yellow portions of these beads and found compounds such as strontium chromate, which produces a distinctive spectrum. This compound mainly came into use after WWII as a non-organic pigment and as a corrosion preventive for the metal surface-finishing industry, e.g., primers, topcoats. Too, I also conducted scans (FTIR) on the seams of what were termed "ancient repairs" for these same tabular Roman face beads only to find cross-linked exoxy polyamides and epoxy siloxane; the latter is a constituent in Super Glue. Just wanted to share what I thought were some interesting findings. No intention to bore anyone, but rather just to make folks think twice (not that they aren't already) about some of the claims regarding "ancient repairs" / "old repairs." ac All rights reserved by Bead Collector Network and its users |
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