I was excited to read Rod Swenson’s excellent article in the November 2014 issue of Pottery Southwest (http://www.unm.edu/~psw/PDFs/PSW-Volume-30r.pdf). He has definitely thought outside the box to come up with some interesting ideas on firing Anazasi style black on white pottery, the information he presents in his article will cause many replicators to rethink or at least to experiment with their firing process. Essentially he states that the firing model developed by Clint Swink, which he refers to as the SP (smothering paradigm), is wrong for a number of reasons. He proposes another model, the NSP (non-smothering paradigm) which uses smaller diameter wood and does not rely on smothering the fire with dirt.
Personally I am an outsider regarding Anazasi black on white pottery replication and reduction firings, I know very little about the subject except what I picked up at the SW Kiln Conference last August. You might say I don’t have a dog in this hunt, but I do have a fairly good understanding of pottery firing principles, fire science, the prehistoric southwest and related subjects. Having had a week or so to ruminate about Rod’s ideas I would like to give my thoughts on the subject.
Parsimony and Earth Moving
Processing Dirt for Smothering is Extremely Labor Intensive and Time- Consuming:… It is likely that the Anasazi, who had no shovels or any of these modern tools would have had only pointed sticks for the task and, after loosening the dirt it would have further had to be collected and sifted or sorted in order to eliminate rocks… Contemporary archaeo-replicators use shovels to do this, but the Anasazi had no shovels… it would have been a very labor intensive and, as will be shown below, an unnecessary time-consuming process.
How are mescal hearts traditionally cooked by native cultures of the Southwest? They are cooked in a pit that is covered with earth. So using earth to keep in heat was a known concept for prehistoric peoples in this region. Mescals also grow and are processed in rocky, mountainous terrain where soil can be scarce, much like the places where pottery was fired.
Of course prehistoric people did not always follow the path of least resistance, more often they followed the way they had been taught. Earth moving was nothing new to these people, after all they were farmers, diggers of irrigation canals and builders of adobe.
Parsimony and Firewood
If one were to attend one of the Leupp or Southwestern kiln conferences held in recent years, one would find archaeo-replicators firing under the SP using modern axes, and often chainsaws, to harvest and process the large diameter (leg-sized, and arm-sized) wood (piñon and more preferentially, juniper) called for by the SP. The Anasazi clearly did not have chainsaws or modern axes, and fuel of this size would have been extremely hard to process without them. Parsimony says the wood they would have used instead would have been of a diameter that could be gathered easily and processed (broken) by hand, under foot or between two rocks, roughly 1 inch to 2.5 inches at most.
The point Rod makes here is good and one I have considered many times, that without iron axes, chainsaws and mauls, the prehistoric potter’s fuel would look a lot different from what many replicators use.
If we are trying to figure out exactly how the ancients fired pottery, then we should be using the exact same fuel they would have used, cut and split firewood is not appropriate. As a person who has studied fire science, I know that this type of fuel will burn differently, different peak temperatures, different timing of peak temperatures, different carbon output, etc.
By this same standard I have a problem with the example firing that is shown in the article because it used split wood. To prove the point that this is the way the prehistoric potters fired, sticks no larger than can be broken with one’s foot should be used and no split wood of any kind.
Similar Firing Regimes
It appears that others were already using similar firing regimes before Rod came up with the NSP. At the 2014 Southwest Kiln Conference I observed William Lucius firing a reduction kiln using smaller diameter fuel without smothering, also Roger Dorr used very small diameter fuel in two different firings, one smothered and one not smothered. In the past year I have been working on firing with very small diameter fuel (1″ diameter and less) to achieve an ash layer similar to what Rod describes in his article.
- William A. Lucius’s Firing Report 2014 SW Kiln Conference
- Andy Ward’s Process for Above Ground Oxidation Firing
I point this out, not to take away from Rod’s excellent work, but to show that what he offers here is not entirely new technology, perhaps more of a new way of thinking about it.
The Assumption or Implication that Smothering is Somehow Necessary is Anomalous
It seems to me that smothering is still needed to explain Mimbres black on white pottery. Rod has shown that iron will oxidize using his firing regime therefore I assume that the hematite paint on Mimbres pottery would also oxidize red under these conditions. Either the Mimbres used the SP or some unknown third firing paradigm.
Salado polychromes are used as evidence to support the NSP, however there are a few key differences between Anasazi black on white pottery and Salado pottery.
- The clays in the southern Southwest are different from the marine clays on the Colorado plateau and mature at lower temps.
- Salado pottery is softer and more crumbly than typical Anasazi pottery, suggesting lower firing temp.
- As far as I know there have been no Salado kilns found.
if Salado pottery was fired at much lower temps using an entirely different firing regime then it’s not a good comparison and can not be used to make the case for the NSP.
Whatever parsimony says, evidence points to the existence of a firing method that can restrict access to oxygen in the later stages of the firing process which the NSP does not. The buried cooking pit is a good example which shows that prehistoric peoples were not unfamiliar with earth smothering nor averse to it, so the SP could be valid or there could be another, third firing paradigm. Others “archaeo-replicators” have embraced other possibilities, for example the “earthen tunnel”.
Rod’s article is well thought out and makes many excellent points, if nothing else it has caused us to think deeper and challenge our assumptions. It has certainly given me food for thought on how to improve my firing process. Thank you Rod.
Please leave comments below if you have any comments or questions about my thoughts.