| Original Message: Colorant Failure |
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Hi Carl, Coincidently, I almost mentioned this in my previous post to you. Another thing that happens to copper-red glass, with some frequency, is that the copper emulsion fails and does not color the glass red in-part. Instead, the glass reverts back to it's natural green color (the base glass being uncolored and nondecolorized greenish glass, naturally colored by iron that is present in the sand when the material is batched). I asked Art to explain this to me a few years ago, but his explanation was not helpful. I said I thought the batch had areas where the colorant was absent, or had reverted to neutral. He said it happens because the glass is "tortured" to become red, and that at places where it's green the copper is present, but not providing a red color. In any event, MANY brick-red glass beads show structural lines or rings, that appear black. If you can get some light through them, you can see they are green. So, Thomas is not incorrect, exactly. The base glass for green-heart beads is uncolored/nondecolorized green glass—varying from pale or yellowish green to saturated green (depending upon how much natural iron is present). I have documented a number of chevron beads that display their red glass reverting to green. It's not common, but it's not unheard-of. And it's totally accidental. Jamey All rights reserved by Bead Collector Network and its users |
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