This question might seem strange to you at first. We think of shoelaces as thin, flexible cords made of cotton, leather or polymer. But: shoelaces made of glass? Hard to image because we know glass from drinking glasses and windows and think of it as hard and fragile.
However, in principle, it is actually possible to thread and even knot glass through the eyelets of shoes! That is, if you use flexible optical glass fibers. We #glasslovers from SCHOTT draw glass fibers that are about as thick (or should we say “thin”) as a human hair.
The breaking loop test is used to test the flexibility of glass fibers. How small can you make a loop until the fibers break? This test has shown that glass fibers with a thickness of 50 microns (thinner than human hair) can withstand a bending radius of about five millimeters. So, threading it through the eyelets of shoes would not be a problem! However, there are limitations: tying a sturdy knot might be tricky – you would not be able to pull it tightly.
In the end, we admit that “normal” laces are more suitable for footwear than glass 🙂. However, there are many areas where glass fibers are the perfect solution as they transmit light and images in high quality.