| Original Message: Observations on iron that I forgot to mention..... |
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Some of my observations on iron. All of my opaque red glass has a high percentage of iron in it. Every old opaque red recipe that I have observed includes a high ammount of red iron oxide - crocus martis is what they refer to it as - see Antonio Neri, "The Art of Glass" - 1612. I would like to try to melt the opaque red again without the added iron.....another project on the back burner..lol
The same glass recipe results shown above if melted in a neutral or oxidising atmosphere (as oppose to a reducing one) would be a dark green transparent color - ranging closer to an emerald through celadon color than compared to an olive shade. I have samples at my shop but not at home or else I would show a pic...sorry. It essentially looks like the green shown in the opaque red above except there is not a trace of the red opaque. With no iron present, the color would just be transparent turquoise. It is my opinion that iron would seem to have to be present in order for the darker green color to be achieved. Here is what a typical ionic copper color looks like. The pic below is pretty much completely iron free. I have melted copper blue many times and the results are always the same - maybe a little bit darker blue than shown in my photo but definitely not green. Disregard the bottom image...
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