fining

glassmaking

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June 26, 2026

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Fining is a crucial step in industrial glassmaking, primarily focused on removing bubbles from molten glass. These bubbles, formed from gases released during the melting process, can compromise the quality of the final product. Fining typically occurs in a conditioning chamber within the furnace, where temperatures are maintained at around 1,300° C (2,375° F). At this stage, the bubbles are dissolved back into the glass melt. Historically, chemicals like arsenic oxide and sodium nitrate were added to aid in fining, but less hazardous alternatives such as sodium chloride, sulfate, or nitrate are now recommended due to environmental and health concerns. The viscosity of the glass is a key property throughout the forming process, allowing it to be shaped and then released in a near-solid state as heat is controlled to increase viscosity.1234

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industrial glass
The conditioning chamber
…removed in a process called fining, which takes place mostly in another section of the furnace known as the conditioning chamber (see Figure 8). From the melting chamber, the molten glass is allowed to pass through a throat in a divider wall, or bridge wall, into the conditioning chamber, where…
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…removed in a process called fining, which takes place mostly in another section of the furnace known as the conditioning chamber (see Figure 8). From the melting chamber, the molten glass is allowed to pass through a throat in a divider wall, or bridge wall, into the conditioning chamber, where…
Read More