Tag Archives: glass beads

The bead that fell apart

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As you can imagine, glass deterioration greatly affects the strength of a piece of glass, but why would a weathered glass spontaneously fall apart after years of apparent stability? We recently had that happen.

64.1.13 before it fell apart

The piece in question is a core-formed bead dating to 500-250 B.C. The bead is made of opaque white glass with trails and prunts of blue, yellow, turquoise, and red-brown glass, and was heavily weathered with a bubbly and pitted thick milky-white weathering crust with patches of dark enamel-like weathering over the entire bead. It has been in the collection since 1964 and had appeared stable. The bead was recently photographed and, to our surprise, an hour or so after it was photographed and safely replaced into a plastic bag, the bead was found broken into 3 larger fragments and numerous small bits.

64.1.13 broken into 3 larger fragments and numerous small bits

So what happened? Direct physical causes may have contributed but do not seem to be the main reason that the bead fell apart, which points towards the glass deterioration itself and environmental factors, especially temperature and relative humidity (RH), playing a role. Blackish dendritic staining (possibly manganese) on all the break edges indicates that there were cracks in the glass which had already gone most of the way through the width of the bead. It is likely that these structural weaknesses along with (slight?) climate changes and the stress from transport and handling caused the bead to break.

Detail showing blackish dendritic staining on break edge

Was this preventable? Maybe not, but to better understand what happened we need to determine if the bead could have experienced any changes in temperature and RH and how big those changes would need to be to affect the glass. In this case the main source of possible climate changes is the photography studio itself, specifically the lighting. We’re hoping that a repeat of the conditions, monitored with a data logger, will give us some insight into the effects lighting for photography has on the ambient temperature and humidity, especially on days when the lights are used for a long time.

Why do I find beads interesting?

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What is it like to work with something that is seemingly as ordinary as glass beads?  What would actually make someone excited to be given such an extensive (perhaps tedious to some) project?  Besides the fact that, perhaps to the detriment of my bank account, I do happen to have a bit of a jewelry fascination, for me, beads tell a story.  A story of a culture andof  the people working with glass who feel a need or desire to own and make such small items, whether for trade, to remember their ancestors, to beautify their bodies, or for one of a thousand different reasons that exist.

As a college student I found myself interested in anthropology and the desire to understand cultures that were not my own, which ultimately led to a degree in cultural anthropology.  I found that I often gravitated to the arts in these cultures, exploring the creation of masks in West Africa or the representation of jaguars in Mesoamerican societies.  In my view, glass beads continue in this path of a useful, desired, and artistic representation of culture.  Cultures all over the world have used beads for centuries for many of the reasons I stated above, leading to a plethora of examinable data, the beads themselves.  As I begin to look at these and try to learn more, I see the similarities and the differences.  Such as the Venetian trade beads that are so well known in West Africa and how those affect the traditional glass beadmaking that was a part of their own culture.  Beads that sometimes look so similar, but to touch one is to feel how differently they were made. 

These beads are far from ordinary and they tell the stories of a people that may no longer be able to tell those stories to us.  For me the most daunting part is first, the sheer number of glass beads made all over the world.  Will I ever know or recognize all of these?  Most likely not, but I’ve made a start.  The other overwhelming problem for me is truly understanding how they were made as I work to better understand the process of glassmaking in general.  Perhaps a beadmaking class is in my future?

-Adrienne Gennett, curatorial assistant