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Test 1 was done when the oven was already cooled down to the room temperature while test 2 was done following the cool down of test 1. Therefore, test 2 did not start from the room temperature---the glass and ceramic were at 30^°^C when the test began. This explains the difference in the above two ceramic plots. In test 1, the cool down was moderate since the doors were kept shut as the lamps were turned off. This allowed the glass and the ceramic to recover the strain more smoothly, as indicated by the absence of a gap between heating and cooling in test 1. In test 2, however, the cool down was extreme since the doors were opened and the lamps were turned off. With the faster cool-down rate, the glass and the ceramic responded faster in its strain behavior and the end points reached positive values as they reached the room temperature. In test 1, the strains do not cross zero because it never recovered to its room temperature.

Figure 5 - Strain vs. Temperature for the Glass in Test 1

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The above plots also clearly show a fluctuation in strain in every temperature interval. This is probably due to strains in both glass and the gage itself. The ceramic strain graph does not fluctuate as much because there is no strain in the thermally neutral material (ceramic); the only strain measurement that is read is the strain in gage itself. As shown in figure 6, the glass in test 2 reaches a higher peak temperature and starts with a higher temperature (30^°^{C) than the glass in test 1(20}°^C). In figure 5, it clearly shows on the graph at what point of temperature the door was opened. This appears to correlate with a significant change in the trend of the graph.

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