Can you melt glass in an oven?

This brief article answers the question of whether glass can be melted in an oven and explains the question in depth. It also covers the uses of glass in an oven and how and when glass can actually be melted.

Can you melt glass in an oven?

No you cannot melt glass in an oven. This is because glass has an extremely high melting point of 400 °C to 1600 °C. Home ovens stand at a temperature limit between 200–230 °C. This is nowhere near the melting point of glass. 

However, glass can break or crack in an oven, not due to the temperature, but rather due to the sudden change in the molecular vibrations that cause the molecular structure of glass to fall apart as it is not strong enough to withstand this.

Can you put glass in the oven?

Yes, you can put glass in the oven. This is not to say that glass cannot break in an oven. Most normal glassware is not oven safe and the heat trapped will cause it to shatter as glass is a poor thermal conductor and sudden changes in temperature will cause it to crack and eventually break.

Microwave-safe glass, however, is made to withstand higher temperatures as it is thicker and more heat-resistant. So be sure to check for the oven-safe label on your glassware. Pyrex and mason jars, for example, are oven safe.

What is glass?

To further understand the melting process of this substance, we must first understand what glass is. Glass is simply a non-crystalline solid that is brittle but hard. It is made from many different raw ingredients that include sand, soda ash and limestone. It is melted to be blown into shapes for various uses including decor.

There are myriad varieties of glass. Some of these are soda-lime glass, Coloured glass, Plate glass, Safety glass, Laminated glass, Optical glass, Pyrex glass, Photo-chromatic glass and Lead crystal glass. Some of these are used in the household, some for cooking, and some for scientific and laboratory purposes. 

Uses of glass in an oven

Glass, as mentioned earlier is a poor conductor of heat. Although it takes a while for it to get heated, once hot, it retains its temperature for much longer. Glass dishes are usually used for dishes that require a moderate temperature to cook. If used for cakes or cookies, the exteriors cook much faster than the interior and this can be problematic. 

Glass dishes can be used for meals like casseroles and pasta as they can be kept out for a longer while as they will remain warm. It should not, however, be used for dishes that go straight from the refrigerator to the oven as this sudden change in temperature can cause them to crack. It is also advisable not to use them for recipes that require a high cooking temperature.

The following are some of the uses of glassware in the oven: 

  • Casseroles (like meat or vegetable casseroles)
  • Baked meat dishes
  • Cobblers (like peach cobblers)
  • Pies ( both fruit and meat/savoury pies)
  • Bread pudding 
  • Baked pasta (all types of pasta such as spaghetti and penne)
  • Crips and crumbles (such as apple crumbles or fresh fruit crisps)

How can glass be melted?

The melting of glass involves an intricate process that cannot be mimicked at home or by yourself. It is done by professionals in specific glass-manufacturing factories. 

Firstly, the high melting point of glass can only be met in furnaces or kilns that are designed specifically to run at incredibly high temperatures; much higher than 1500 degrees celsius. 

The raw materials of the glass are first put into these kilns to be heated up to 1500 degrees celsius. After this, a propane blowtorch is used to heat it a further 900 degrees until it turns a bright orange. At this point, the glass is soft and stretchy and can be blown, moulded or pressed into the desired shape. The glass is then very slowly cooled down so that it doesn’t break. 

Glass can notably be melted at home as long as there is a kiln present. The final stages of heating for it to be melted can be done using a blowtorch. However, safety gear MUST be worn throughout. However, even if done at home, not all glass can be used for this process. Do note that this is quite dangerous and should be done with utmost care.

Conclusion

While it is not possible for glass to melt in an oven, it can easily be broken if not oven-safe. Also, keep in mind that even oven-safe glass can be damaged/broken/cracked if not used carefully. Prevent them from being subject to sudden temperature changes and high heat and you’re good to go!

Citations

https://www.berlinpackaging.com/at_what_temperature_will_glass_break/

https://www.allrecipes.com/article/glass-vs-metal-baking-pans/

https://sciencing.com/how-to-melt-glass-with-a-torch-5730422.html

https://crafts.stackexchange.com/questions/3337/is-it-possible-to-melt-a-glass-bottle-without-a-kiln

https://www.glassallianceeurope.eu/en/what-is-glass