This week in the lab, my group fired the pots we made in week 3. Our firing took place in a metal fire pit about two feet in diameter. We began by warming the pots around a small teepee fire in the center of our pit to raise the temperature to 230 degrees Celsius. This helps to dry out the pot and prevent cracking and explosions during firing.
I tracked the temperature of two pots, one made from our clay and temper mixture and the other from Arb clay (circled in blue and red respectively). The following is a graph of the temperature of the two pots over the course of the warming period. During the process, we rotated the pots often and ensured that every side was warming evenly. In particular, we ensured that the bases (the thickest part) were adequately heated to ensure dryness.
After warming the pots at 51 minutes into the experiment, we briefly removed them from the fire pit at 51 minutes, flattened the coals, and then returned them stacked in a pyramid. We then built up a larger fire on top of the pots with the goal of firing them into ceramic. The fire quickly reached around 830 degrees Celcius and stayed in the vicinity. Temperature data was difficult to obtain as the pots were covered. Below is what I was able to measure beginning at 60 minutes when we lit the fire from the embers.
Of note, at 108 minutes, we began to break apart the fire but did not excavate the pots yet. Additionally, at 130 minutes, we removed the pots from the fire and brought them to the edge of the larger fire to slowly cool.
Of the nine pieces of pottery that we ended up firing, all nine remained. One had some major spalling, but the rest stayed fully intact. Below are the dimensions for Pot 1 at several points in the creation process.
| Pot 1 | Original | After 1 day | Loss | After firing | Total Loss |
| Weight | 579 g | 521 g | 58 g | 471 g | 108 g |
| Height | 9.9 cm | 9.1 cm | 0.8 cm | 9.2 cm | 0.7 cm |
| Diameter (rim) | 7.7 cm | 7.3 cm | 0.4 cm | 7.5 cm | 0.2 cm |
| Diameter (widest) | 9.8 cm | 9.4 cm | 0.4 cm | 9.4 cm | 0.4 cm |
| Wall section | 0.8 cm | 0.66 cm | 0.14 cm | 0.689 cm | 0.111 cm |
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