Lloyd Strickland’s (professor of Philosophy and Intellectual History, Manchester Metropolitan University) fascinating April 9, 2024 essay on The Conversation (h/t April 10, 2024 news item on phys.org) illustrates the long and winding road to scientific and technological discoveries, Note: Links have been removed,

Separate teams of Chinese and American scientists are reported to be developing body armour using the silk from genetically modified silkworms. The researchers modified the genes of silkworms to make them produce spider silk instead of their own silk.

Harnessing the properties of spider silk has been a longstanding aim because the material is as strong as steel, yet also highly elastic. However, the idea of using silk to make bulletproof vests is not a new idea. Instead, it goes back centuries.

The invention of the silk bulletproof vest is often credited to the American physician George Emory Goodfellow (1855–1910), following his observation that silk was impenetrable to bullets.

But the idea was in fact proposed more than two centuries earlier by the German polymath Gottfried Wilhelm Leibniz (1646–1716), best known as inventor of calculus and binary arithmetic. …

You’ll notice it’s almost two centuries between the idea being proposed and someone working out a way to make a silk bulletproof vest. First, Liebniz (from Strickland’s April 9, 2024 essay), Note: Links have been removed,

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In one of these little-known writings, unassumingly entitled “Plan for a military manufacturing process”, Leibniz sought to identify a material suitable for making a lightweight, flexible, bulletproof fabric. He briefly considered metal wires, layered metal sheets, and layered “goldbeater’s skin”, which is a material made from ox intestine. However, he devoted most of his attention to silk.

Whereas Goodfellow had observed the impenetrability of silk by bullets, Leibniz never had. Instead, he thought silk was the most promising material for a bulletproof fabric due to being lightweight, flexible, and strong. “Of all the materials we use for fabrics, and which can be obtained in quantity, there is nothing firmer than a silk thread,” he wrote.

Noting that silk was never firmer than in the cocoon, “where the silk is still gathered in the way that nature produced it”, Leibniz proposed making a fabric formed of silkworm cocoons tightly pressed together with a little glue.

He realised that while such a sheet could not easily be pierced, due to the tightly-woven silk in the cocoons, it would be prone to tearing where one cocoon met the next. Thus, he inferred that a bullet would not make a hole in the fabric, but instead tear whatever cocoon it hit from the surrounding ones, and drive it into the body, similar to what Goodfellow would observe with the silk handkerchief two centuries later.

Leibniz’s solution to the tearing problem was to propose layering sheets of pressed silkworm cocoons on top of each other. He illustrated this with a rudimentary diagram of a row of circles stacked on top of one another in a lattice arrangement, where a small interstice is left between adjoining circles.

Layering cocoons in such a hexagonal packing arrangement ensures that the weak parts of one layer are covered by the strong parts of another. This way, the fabric would not tear or be pierced when hit by a bullet. The result, Leibniz claimed, would be a fabric suitable for covering almost the whole body, especially if it was made to be oversized, affording the wearer freedom of movement.

Leibniz never realised his proposal to create bulletproof clothing using silk.

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Strickland’s April 9, 2024 essay offers more about how Goodfellow’s field observations led to the invention of the first silk bulletproof vest by a Catholic priest.

Scott Burton’s undated article for bodyarmornews.com on spider silk and bulletproof body armour offers information about current efforts by US and Chinese scientists to incorporate spider proteins by gene editing silkworms capable of producing enough hybrid silk for enhanced body armour.

A century later, what appears to be the latest breakthrough was announced in a September 24, 2023 news item on chinadaily.com (and noted in Burton’s article),

Chinese scientists have developed the first whole full-length spider silk fiber obtained from genetically-engineered silkworms, exhibiting a six-fold toughness when compared to a bulletproof vest.

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The results pave the way for spider silk’s commercialization as a sustainable substitute for synthetic fibers, and it can be used in making surgical sutures and comfortable bulletproof vests, according to the study.

Here’s a link to and a citation for the paper,

High-strength and ultra-tough whole spider silk fibers spun from transgenic silkworms by Junpeng Mi, Yizhong Zhou, Sanyuan Ma, Xingping Zhou, Shouying Xu, Yuchen Yang, Yuan Sun, Qingyou Xia, Hongnian Zhu, Suyang Wang, Luyang Tian, Qing Men. Matter Volume 6, ISSUE 10, P3661-3683, October 04, 2023 DOI: https://doi.org/10.1016/j.matt.2023.08.013 First published online: September 20, 2023

This paper is behind a paywall.