Week 8: Firing Pottery: Straw, Saw Dust, & Bark

Zoe Orlin, Holland Votaw, Zachary McCrary

This week in lab, we constructed fire-pit kilns in order to fire pots we had made under the guidance of ceramics professor Kelly Connole the previous week. We had spent the previous week learning about Anglo-Saxon pottery and its chaine operatoire. Specifically, the entire process that must be undertaken in order to make a ceramic item for use. We also watched a video on African pottery. 

Through these materials, we learned a lot about the importance of perfecting the chaine operatoire of making ceramics. In the early Anglo-Saxon period, much of the previously used technology to make ceramic items in the Roman age was lost, and the Anglo-Saxons had to start from scratch. As such, ceramics developed from a task undertaken by each individual household to produce goods specifically for household use, into a larger, more streamlined operation as was seen in the Roman age. Through our lab, we hoped, through experimental methods, to learn about how pottery might have been fired without use of a massive kiln. In this process, we also explored the different steps that must be taken in the chaine operatiore to prepare a “kiln” and ready it to be used for the firing of pots. As we began to understand through literary sources and gained a deeper understanding of through the lab activity, care must be taken to ensure each step of the process goes as it should or else resources and man hours are lost. And, as showcased in the video on African pottery firing, we also hoped to gain a deeper understanding of the communal aspect of pottery making. 

Process

Upon arrival at the art park, each group picked either 4 or 5 pots to track changes in over the course of the firing process. These pots were weighed and measured before firing.

We began by building three small fires in the art park. Once the fires were burning consistently, each group of 8 placed their pots in a ring approximately 1 foot away from their respective fire.

Over the course of the next thirty minutes, each group generally moved their pots closer towards the fire. Other small adjustments, including rotating the pots both laterally and vertically, were made over this period at Kelly’s suggestion. At this stage, we began to take the temperature of the tracked pots every 10 minutes using a temperature gun.

Some of the pots, especially those having been moved in rapidly towards the hotter fires, had pieces explode at this stage.

As this fire burned down to coals, two of the groups ended up moving their pots slightly further away from those coals to give adequate room to construct the next stage of the process. Each group in turn flattened out the bed of coals, then placed their pots in a pyramid in the middle of the coals.

We then built larger, hotter fires around the pot pyramids. These fires completely surrounded the pots, and we let them burn down significantly as well. 

As these fires were burning down, it began to rain quite hard, and each group smothered their fires with a different material: sawdust, tree bark, or straw. We left these fires to smother overnight.

Sawdust:

To smother with sawdust, the sawdust group poured a bucket of sawdust directly into the open flame. We had to do this earlier than expected due to the sudden downpour of rain. The sawdust was incredibly effective at smothering the fire. The flame went out immediately, and within a few minutes, there was very little smoke still coming out of the fire pit. 

Bark:

For the bark smothering, we used a pile of (very wet) bark from the art park, which was mostly bark, but also included a significant amount of dirt and other organic/non organic material; none of which ended up smothering the fire particularly well. Even when we had covered the pile of pots entirely, smoke continued to creep out in large quantities. We added more bark, and then more dirt, to no avail. It seemed as if the fire was contained, but still burning a considerable amount; the rain appeared to have little effect, and this pile continued to smoke through the night and up until our next class period on Friday (despite heavy, heavy rain that morning). 

Straw

The straw group placed an entire bale of damp straw onto our fire, trying to spread it evenly to prevent any wind from being able to reach the fire. During the initial application process, the fire continued to steam and smoke, even through the straw. The amount of smoke significantly decreased very briefly, but then became strong once again, even in the rain.

The next day, we all arrived and checked on the fires. Overnight,to further smother the fires, Zach and Kelly had placed trash can lids over each of the smothering materials, which were removed later in the day.

Sawdust:

Despite how effectively the fire seemed to have gone out the previous day using the sawdust, the sawdust-smothered fire re-lit overnight. In order to extract the pots, we had to rake through the ash that was the burnt sawdust. We had to do this very carefully, lest the fire would light again unexpectedly. 

Bark:

As mentioned earlier, the bark smothering allowed our pile to burn continuously through the night, and well into Friday – it only stopped burning/smoldering once we had spread the coals out and removed the pots (which were still very very hot at the beginning, but cooled off pretty quickly).

Straw

Portions of the straw continued to catch fire overnight & had to be put out with the trash can lids, even accounting for the rain. When we arrived and began to slowly remove the straw, part of the straw had continued burning under the trash can lid.

Results 

In the sawdust group, we only had one pot completely shatter in the fire, though it is important to note that this happened before the sawdust was added to smother the fire. Besides this, we had very consistent results. All the pots made out of regular clay had small cracks in them, but no cracks immediately large enough to break the pot. However, after some time out of the fire, one of the pots cracked in half. Regarding the pots made out of arb clay, none of them cracked at all. However, these pots did not seem to fire as much as the pots made out of regular clay, which may be why they were less fragile upon extraction. 

Conclusion

The firing process, from start to finish, produced an experience that is very familiar to other lab experiences: there was a lot of waiting, but waiting that couldn’t be abandoned (i.e., we had to stick around as the fire got to temperature, and up until it was smothered). Perhaps another task could be done at the firing site (perhaps spinning, or perhaps cooking over the fire before it was smothered) so it is not as if this time was unusable. For us, it provided a good amount of social opportunity. 

Perhaps because we were removed from the direct use of the pots we were firing, the spaulding and breakage that occurred was sad, but not actually a big problem, since the pots were not big enough to really be used for anything (except perhaps some dried flowers). In relation to the previous week’s lab, however, the clay-to-fire-to-ceramic process stands out as particularly involved, but only for stretches of time. Mixing and forming the clay is a process that requires a dedicated amount of time to do, and then the pieces can be left to dry for days, weeks, or even months before firing; once the firing process starts, it is intensive and consuming while the pots are preheated and then when smothered. But in between the forming and the firing, and the initial fire and the smothering, the ceramic process does not require much other than occasional attention (in firing, occasional attention but continual presence for a period); it also produces an incredibly long lasting material, that once made would only need to be replaced if broken, or if more storage space is needed.

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