Glass fan heating glass in an oven.
Various glass production techniques are used all over the world. Float glass and glass blowing are two of the most common and important methods. The best production method depends on how the glass will be used, as different techniques can reveal different characteristics in the finished product. It is also important to select the right raw materials. For things like scientific glass and cooking vessels, the glass needs to be durable, resistant to high temperatures, and very strong.
Glass blowing can be performed to mold molten glass into colored plates.
In float glass production, manufacturers place liquid glass in a hot bath of molten tin. The two components do not mix and the glass forms a thin layer on top. The resulting glass sheet can slowly move through the facility to cool until it is ready to be cut. Manufacturers using this production method have extremely large facilities to accommodate all the different stages of production.
Historical methods of producing sheets of glass were less reliable and tended to create wavy patterns in the glass. The distinctive appearance of older glass panels is often attributed to the aging of the glass over time. This is not really the case; the glass had the same ripples and droopy look when it was new.
Glass blowing involves inflating the glass to empty it and create a container. You can create a freeform object or blow into a mold. Historically, glass was produced by rolling clay molds into molten glass, waiting for it to cool, and then breaking the mold to remove it and leave the finished glass container behind. When this technique was replaced by blown glass, it was a significant development in the history of glass production.
Glass can also be laminated in a production method where partially melted glass is squeezed between giant rollers to create a flat sheet. For tiles, glass production techniques can include firing glass paste in molds until it melts and creating sunken glass using textured molds to engrave and shape the glass during firing. Glass tile producers can also use pieces of glass fired in a mold to create a solid, patterned piece of glass.
Art conservators must be familiar with glass production techniques if they work with glass objects. It can be important to understand how a piece was made. If there is a problem, such as instability due to impurities, knowledge of production techniques can help the conservator fix the glass properly. While glass is normally extremely strong and stable, some antique pieces are fragile and require special care.