The design of equipment and thermal routines for annealing glass particles

The effect of re-annealing on the distribution of refractive index in a windscreen and a windowpane

“…The optimisation of annealing procedure for different glass objects was performed and considered results obtained by Locke et al [3]. These authors took five parameters into account: the upper annealing temperature, time of holding the upper temperature, the lower annealing temperature (when the slow cooling can be replaced by rapid cooling), time of the annealing process, and the cooling rate.…”

“…The elemental composition is often determined by XRF, SEM-EDX, ICP-AES and LA-ICP-MS methods. To improve the discrimination of glass fragments the process of annealing is often recommended [1][2][3][4][5][6][7][8]. Although the annealing process was used mainly for classification purposes [4,5,8] or identification of toughened glass [2,6], it is suggested by many authors [1,5] that it could successfully be used for further discrimination of glass fragments by classifying those of the same RI as tempered or non-tempered.…”

A study of the performance and utility of annealing in forensic glass analysis

“…Improving the annealing process then became the focus for Locke et al [18] who tested the design of equipment and thermal routines used for the annealing technique. This investigation recommended the use of a programmable furnace to control the temperature and a metal block to provide a uniform temperature.…”

“…However, it may be desirable in some cases to characterise the glass fragments further. Methods that have been suggested include examination of the surface of the glass to determine whether it is flat or curved [4,5], the examination of the elemental composition [6][7][8][9][10][11][12][13][14], and the examination of the change in refractive index upon annealing [15][16][17][18][19][20][21][22][23].…”

Effects of Annealing on Toughened and Non-Toughened Glass

“…Stresses in large pieces of toughened glass, which are easily observed under polarized light, are not visible in fragments less than a few millimetres in size. During the last decade workers at the Home Office in the United Kingdom have attempted to classify sub-millimetre glass fragments as being either toughened or non-toughened by annealing the fragments and re-determining the RI (2,(4)(5)(6)(7). They found that the magnitude of the difference 1 in RI before and after annealing (~RI) is directly related to the temper of the glass sample (6,7).…”