Color and Lighting

Cloudy, untreated amber bead.

Amber bead under fluorescent light.

Same amber bead with LED backlight.

Same amber bead with LED backlight.

I’ve mentioned a number of times how the lighting on or behind a bead can change its color. Black beads are actually cobalt blue, purple, green, or even hot pink when view with an LED light shining through. Brown beads often become yellow or orange with LED backlighting, and blue beads often appear much lighter.

It’s important to record both colors, one with typical fluorescent or natural lighting and one with LED backlighting. Why? A few reasons, actually.

CRG 010Taking the color of the bead in natural light is highly important because that is likely the color that bead appeared to the vast majority of people who ever used it. In terms of how people in the past viewed the bead, the natural or fluorescent lighting will give you the most accurate color. I am curious about candlelight, firelight, or sunlight – if there are beads that appeared one color, but when you held it up to a candle or fire it would change. I haven’t been able to investigate that yet, but generally speaking, the color changes you see with an LED light wouldn’t be visible at all under any other kind of light – they’re often quite dark even with the LED light.

Recycled, wound bead from Scotland

Recycled, wound bead from Scotland

So why bother with the LED light at all? Chemistry. Supply of glass to make beads. Production and manufacture. All of the above.

The color of a glass will change its chemistry to a degree, based on the colorants used. It’s good to know your bead was made with very dark blue glass rather than black or purple before you test it chemically, so that you know what to expect and what to compare it to. Comparing the chemistry of a dark green bead to a dark purple bead isn’t as good as comparing it to another green bead.

Colors of 'black' glass from Scotland with LED shining through.

Colors of ‘black’ glass from Scotland with LED shining through.

Colors of 'black' glass from Thailand with LED shining through.

Colors of ‘black’ glass from Thailand with LED shining through.

It’s also good to know where the supply of glass is coming from for black glass. Often, the darker glasses tend to be recycled, and looking at the colors for beads that appear black can give us clues as to the source of the recycled glass. For example, if you look at all the apparently black beads in Scotland that I have data for, 71.4% are truly black, 15.2% are hot pink, 9.5% are blue, 2 are red, and only 1 each are purple or orange. In Thailand, 87.7% were black, 6% were blue, 5% green, and 1 was brown. That’s a pretty stark difference. For one thing, there’s far more variety in the Scottish colors, and it’s a big contrast from blue to hot pink. This leads to questions of where the glass is coming from, if it’s vessels of that color or if they’re coloring the glass to that degree without turning it purple.

It also leads to questions of manufacture. Are the black/hot pink beads being made by the same person or workshop that made the truly black beads or the black/blue beads? How well have they mixed their colors? And what in the world is going on with the hot pink ones?

If I had only recorded the color under fluorescent lighting, I wouldn’t have any knowledge of this difference. While most people in the past likely didn’t know it either, the manufacturers most likely did, because they would have known the source of the glass they put into these beads. Likewise, if I had only recorded the color under LED lighting, I wouldn’t have any knowledge of how most people in the past perceived the bead. Both are incredibly valuable for research, and both give a lot of insight into the past.

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About Heather Christie

Heather is an archaeologist, photographer, and writer whose research focuses on beads and bead trade, particularly in a maritime sense. She's currently working working on a PhD in Digital Design (focusing on heritage visualisation) at the Glasgow School of Art.
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