downdraw process

glassmaking

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Last updated

June 25, 2026

Quick Summary

The downdraw process is a method used in glassmaking to create tubes and rods. In this technique, molten glass is directed vertically downward through a specially designed orifice. This orifice controls the thickness of the tube's wall and the shape of its internal bore. The glass is then pulled from below by traction. This process is versatile, allowing for the creation of complex cross-sections, such as oval bores used in thermometers. Additionally, it's possible to fuse strips of a different type of glass to the primary stream using an auxiliary melting pot.1

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industrial glass
Tubes and rods
In the downdraw process, molten glass is allowed to flow vertically downward through a defined orifice and is pulled by traction from below. The orifice controls the thickness of the tube wall and the shape of the bore. The process allows the forming of complex cross sections,…
Read More
In the downdraw process, molten glass is allowed to flow vertically downward through a defined orifice and is pulled by traction from below. The orifice controls the thickness of the tube wall and the shape of the bore. The process allows the forming of complex cross sections,…
Read More