Some fibers like it hot

Since the beginning of time fire has fascinated us. After the taming of wild fires in the Paleolithic Era encouraged people settle down, fire still contributes to human progress today in a large number of industries. Whether it is used to generate heat, disinfect, or melt or burn objects, the same properties that make fire useful also make it dangerous, since very few materials can withstand fire.

This makes heat- and explosion-resistant materials all the more important. Glass is often used here, but why? To find out what temperatures our glasses can withstand, we want to do a thought experiment to see if you could roast a marshmallow on them.

#GlassFacts: Could you roast a marshmallow on rigid glass fibers?

Many of us have burned our fingers when holding our hand over the fire for too long. So we know it can get very hot. But did you know that rigid glass fibers can be used to roast a marshmallow?* Since SCHOTT glass fibers are unaffected by temperatures of up to 400° Celsius, they can withstand the temperature for a long time without deforming.

Glass fibers can even withstand temperatures up to 600° Celsius for a short time. Only after 30-60 minutes do the fibers slowly begin to soften and change their shape. Of course, by then the marshmallow is long burned and coal-black.

The glass fibers owe this heat resistance to the fact that glass does not conduct much heat, which means they offer clear advantages over plastic fibers. Thanks to this property, no gloves would be needed to hold the rigid glass conduit over the campfire.

*PLEASE DO NOT TRY THIS YOURSELF. SCHOTT are experts in glass. Not every glass is the same and this experiment depends on many factors, such as the composition of the glass, the thickness of the material, and temperature differences.

There are more practical applications of glass fibers. If you want to look into hot environments or transmit light though them, you can’t beat glass. This is because light guides and image guides made of glass fibers can transport information from hot environments where sensors and cameras would break down. In this way, the fibers can bridge long distances and close the gaps between the camera and the area that needs to be seen. This is particularly beneficial for sensor technology and metrology.

For example, the high temperatures in steel plants make it impossible for cameras to operate because they would immediately melt plastic. Nevertheless, it is necessary to check whether liquid iron transported by automatic cranes is spilled. This is where image guides can offer a flexible but robust solution.

High temperatures also occur in the reprocessing of medical products. In sterilization processes such as autoclaving, rigid endoscopes such as laparoscopes or fiber-optic dental rods are heated up to 137° Celsius. This is no challenge for the temperature-resistant glass fibers.

Of course, there are better uses for glass fibers than roasting marshmallows on them. But maybe the next time you are sitting around a campfire or brooding over a problem in the office about light or image transmission, you will think of our glass optical fibers. They love fire as much as we love glass.

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Dr. Haike Frank
Lighting and Imaging
SCHOTT AG

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