| ASTM # | Test Name | Description |
| C-158 |
Strength of Glass By Flexure. T9501 |
Flexural strength is determined in three-point or four-point bending on bars of rectangular or circular cross-section. Between ten to thirty specimens per type/brand is recommended by ASTM. |
| C-336 |
Annealing Point And Strain Point of Glass By Fiber Elongation. T9502 |
The annealing point of a glass is defined as the temperature at which a round fiber, nominally 0.65 mm in diameter, elongates under a load of 1.0 kg at a rate of 0.14 mm/min when it is cooled at a rate of 4°C/min. the strain point is determined by extrapolation of the annealing point data as the temperature at which the elongation rate is 0.0316 times that at the annealing temperature. A representative specimen of 50 gm or more of flame workable glass in pieces a minimum of 5 mm in diameter is required. Fritted or ground specimens must be re-melted to obtain a piece large enough from which fibers can be drawn. |
| C-338 |
Softening Point of Glass By Fiber Elongation. T9503 |
The softening point of a glass is defined as the temperature at which a round fiber, nominally 0.65 mm in diameter and 235 mm long, elongates under its own weight at a rate of 1 mm/min when the upper 100 mm of its length is heated at a rate of 5°C/min. A representative specimen of 50 gm or more of flame workable glass in pieces a minimum of 5 mm in diameter is required. Fritted or ground specimens must be remelted to obtain a piece large enough from which fibers can be drawn. |
| C-598 |
Annealing Point And Strain Point of Glass By Beam Bending. T9575 |
The annealing point of a glass is defined as the temperature at which a 3-point loaded beam, nominally 3 to 4 mm in cross section on a 50 mm span, elongates under a load of between 0.2 kg and 1.0 kg at a rate determined by the span, load, and moment of inertia when it is cooled at a rate of 4°C/min. the strain point is determined by extrapolation of the annealing point data as the temperature at which the elongation rate is 0.0316 times that at the annealing temperature. A representative specimen, nominally 3 to 4 mm in cross section and 75 mm in length, is required. |
| C-657 |
DC Volume Resistivity of Glass. T9577 |
Surface and volume electrical resistivity of insulating materials are determined by DC, as well as by AC methods. Specimen dimensions and electrode configuration are determined on an individual basis. |
| C-829 |
Liquidus Temperature of Glass |
The liquidus temperature is the maximum temperature where equilibrium exists between the amorphous glass and its primary crystalline phase. A sample of about 30 g is crushed to -20 mesh and placed in a platinum boat with dimensions of about 0.5 x 0.5 x 6.0” The glass specimen is held at a specified temperature gradient over its entire length for a period of time necessary to obtain thermal equilibrium between the crystalline and glassy phases. The specimen is quenched and viewed with a microscope to determine the glass / crystalline interface location and corresponding temperature. |
| C-965 |
Viscosity of Glass Above the Softening Point |
The viscosity of glass above the softening point is determined using a platinum alloy spindle immersed in a crucible of molten glass. The platinum crucible is placed in a vertical tube furnace capable of 1600 C. The viscometer is mounted above the tube furnace is capable of measuring from 1.5 to 5.0 Poise. About 400 g of glass is necessary for the test. After the data is collected, it is fit to a Fulcher equation to describe the viscosity / temperature relationship. |
| |
Softening Point of Glass By Penetrometer (Labino Method). T9160 |
A 3/16" cube specimen is supported on a horizontal platform inside a furnace. A probe rod is lowered to contact the glass specimen. As the furnace is heated at a rate of 25°C/min, the probe penetrates the glass specimen. the temperature at which the probe penetrates a certain distance is correlated to the softening point. Three representative specimens, approximately 3/16" by 3/16" by 3/16", are required. |
