ASTM C965 - 96(2012)

    Standard Practice for Measuring Viscosity of Glass Above the Softening Point

    Active Standard ASTM C965 | Developed by Subcommittee: C14.04

    Book of Standards Volume: 15.02


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    Significance and Use

    This practice is useful in determining the viscosity-temperature relationships for glasses and corresponding useful working ranges. See Terminology C162.

    1. Scope

    1.1 This practice covers the determination of the viscosity of glass above the softening point through the use of a platinum alloy spindle immersed in a crucible of molten glass. Spindle torque, developed by differential angular velocity between crucible and spindle, is measured and used to calculate viscosity. Generally, data are taken as a function of temperature to describe the viscosity curve for the glass, usually in the range from 1 to 106 Pa·s.

    1.2 Two procedures with comparable precision and accuracy are described and differ in the manner for developing spindle torque. Procedure A employs a stationary crucible and a rotated spindle. Procedure B uses a rotating crucible in combination with a fixed spindle.

    1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.


    2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

    ASTM Standards

    C162 Terminology of Glass and Glass Products

    E220 Test Method for Calibration of Thermocouples By Comparison Techniques


    ICS Code

    ICS Number Code 81.040.10 (Raw materials and raw glass)

    UNSPSC Code

    UNSPSC Code 72153000(Glass and glazing services)


    DOI: 10.1520/C0965-96R12

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