Making Glass in a Grill [With Video!] | Popular Science

Making Glass in a Grill [With Video!]

The author creates an ornament—using his barbecue

All the components of glass can be found in two places: the beach and the laundry room. It's possible to melt pure white-silica beach sand into glass, but only at temperatures of 3,000 to 3,500°F. Washing soda, lime or borax (a traditional laundry aid) added to the sand disrupts the quartz-crystal structure of silica and reduces the required temperature to a more practical, though still dangerous, 2,000°F, which I achieved with a backyard grill and a vacuum cleaner. Glass is thought to have been discovered around 7,000 years ago by Phoenician merchants when cooking fires were built over sand that, by chance, had some of these substances mixed in.

Achtung!

Theo Sez: It is very dangerous to push a charcoal grill beyond its intended temperature limits. Do not try this method of glassmaking at home. Wear a dust mask when handling silica sand.

Mike Walker

A charcoal fire fed with air from the bottom is hot enough to melt the combination of those materials into glass but not hot enough to make it truly liquid, so bubbles tend to remain and make the glass cloudy. I mixed the finely ground ingredients together and heated them in a cast-iron pot, then poured the molten glass into a graphite mold and pressed it down with a graphite stamp.

Soda-lime glass has the lowest melting point but must be cooled slowly to avoid shattering from thermal stress. Borosilicate glass, commonly known as Pyrex, melts at a higher temperature but can be cooled more rapidly. I made a medallion out of each and just left them in the fire as it died down over a few hours.

Although making glass from sand is satisfyingly primal, starting with actual glass is more practical. Old test tubes yield high-grade borosilicate glass; wine bottles, colored glass. Watch out—it's all very sharp and hot when molten!

Click here for a slideshow of the glass-making in action. And turn the page for video.

Like what you see? For more Gray Matter, head to popsci.com/graymatter. And for Theodore Gray's one-of-a-kind periodic table poster, check out periodictable.com/posters

Too Hot to Handle

Sand mixed with ingredients normally used for laundry form molten glass in a cast-iron pan on the author's grill.

Mike Walker

Too Hot to Handle

A firebrick lid keeps heat in and ashes out.

Mike Walker

Making a Mark

I placed the glass in a mold and stamped a pattern.

Mike Walker

Cooling-Off Period

Soda-lime glass can shatter if cooled too quickly.

Mike Walker

All Done

Glass made in this way isn't entirely transparent, but my finished ornament [shown here along with its mold] looks pretty nice.

Read how Theo did it here.

Mike Walker

tout

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