Milking Golden Silk Threads Helps Solve A Natural History Mystery...

In the Dog Days of Summer 2024, Laini Allen in Park and Program Services received an email from a historian looking to solve a thread mystery. Christopher Cascio, the historian, is the Alan W. Rothschild Assistant Curator of Patent Models at the Hagley Museum and Library in Wilmington, Delaware. Hagley holds nearly 5,000 patent models in its collection, the second largest museum collection in the United States. The patent models symbolize thousands of innovations from inventors from all walks of life who submitted a miniature model of their invention to the U.S. Patent Office in the 1800s. It was once a requirement for a scale model to accompany a patent application, sometimes being crafted by the inventor, other times made by a professional model maker.

Mr. Cascio was looking to confirm if the material attached to a patent model in their collection was a particular spider silk. He wrote "During the Civil War, two Union officers in the 55th Massachusetts were stationed on Folly’s Island during the siege of Fort Wagner. They found a curious spider, now known as the golden silk orb weaver, and managed to collect yards upon yards of spider silk directly from the animal. They patented a machine for harvesting silk from live spiders in January 1866. This patent model is in our collection here at Hagley…and it has some golden colored thread wound around a spool on the machine. The conservators can confirm that it is silk. But they can’t determine if it is run-of-the mill silkworm silk or a spider, or even from a golden orb weaver spider, without a sample for comparison. And golden orb weavers are hard to come by up north even this time of year. Would any naturalists on staff be willing to collect a sample and send it to me."

Kristina Wheeler, CCPRC Naturalist, fielded the email and then jumped into the field to seek out one of these special spiders. Golden Orb Weaver females are colorful and conspicuous arachnids sometimes nicknamed Banana Spider. The dragline thread produced by this spider is biodegradable, stronger than steel by a factor of six and is economically valuable. Kristina was able to collect a small sample from a shy donor near the back of the parking lot at headquarters and sent it off to help provide a clue in the material mystery.

After a few weeks went by, Chris replied "The thread on the model is not spider silk. A textile conservation lab determined that the thread is modern mercerized cotton. At some point, the owner of the patent model wove the cotton thread around the mechanism to demonstrate how the machine worked. But your efforts were not wasted. The textile conservators were VERY HAPPY with the sample you provided! There is an international database of images of every sort of material that clothing is made from. And, until now, they did not have an image of spider silk under microscopy. We know garments have been made from spider silk for centuries. Now they have a sample for comparison! Who knows? Maybe there are other garments made from spider silk languishing in drawers and cabinets in museums all over the world that can now be identified thanks to your sample. I very much appreciate your help with this project, as do other textile researchers around the world!"

Kate Sahmel is one of the textile conservators at Winterthur Museum and Library in Wilmington. She wrote about the fibers and the image she sent to the reference library. “The fibers on the [model’s] spool have a slight twist to them, which indicates cotton.

Non-mercerized cotton (first half of the 19th century and earlier) has a ribbon-like appearance, with flat, twisty fibers. Mercerized cotton has a similar appearance but is more “plumped up” due to the mercerization process. In contrast, silk fibers are generally smooth and glass-like. Sometimes I describe them as looking like glass rods (although obviously with some bend to them).”

Fortunately, producing garments from this type of silk did not prove commercially viable. Otherwise, there might be a lot of exhausted spiders out there. CCPRC's Natural History Interpretation Team was thankful to be a part of solving this mystery for the Hagley Museum and other curious textile conservators worldwide.