What is "Spalling" in Native American Pottery?

Spalling is a common issue that occurs on Native American pottery, particularly on pieces that were created prior to the introduction of kiln-firing techniques. It is a process in which small pieces of the pottery's surface break off or flake away, often resulting in the gradual deterioration of the piece over time. Understanding the causes and mechanisms of spalling is essential for preserving and maintaining these cultural artifacts for future generations.

One of the primary causes of spalling on Native American pottery is the exposure of the pottery to environmental factors, such as changes in temperature and humidity. This is particularly true for pieces that were created using the traditional method of pit firing, which involves burying the pottery in a shallow pit and lighting a fire on top of it. As the pottery heats up, it can experience rapid changes in temperature, causing the surface to expand and contract. Over time, this repeated expansion and contraction can cause the surface to crack and break, leading to spalling.

Another common cause of spalling on Native American pottery is the presence of natural inclusions in the clay used to create the piece. Inclusions are small particles of organic or mineral matter that are present in the clay before it is fired. While inclusions can add interesting patterns and textures to the pottery, they can also make the clay more prone to spalling. This is because inclusions do not expand and contract at the same rate as the surrounding clay during heating and cooling, creating stress points that can lead to cracking and flaking.

A third factor that can contribute to spalling on Native American pottery is the use of low-quality clay or improper firing techniques. Pottery that is created using clay that is too wet, too dry, or contaminated with impurities is more likely to experience spalling.

Additionally, pottery that is not fired at the appropriate temperature or for the appropriate amount of time can be more prone to spalling, as the clay may not be fully vitrified (i.e., converted into a glass-like substance) during the firing process.

Despite the challenges posed by spalling, there are several strategies that can be used to help prevent it from occurring or to mitigate its effects. One of the most important steps that can be taken is to properly store and display Native American pottery in environments that are stable and free from extreme temperature or humidity fluctuations. This can help to prevent stress on the surface of the pottery and reduce the risk of spalling.

Another important strategy for preventing spalling is to use proper cleaning techniques when handling Native American pottery. Harsh cleaning chemicals or abrasive materials can scratch or weaken the surface of the pottery, making it more prone to spalling over time. 

In conclusion, spalling is a common issue that can affect Native American pottery, particularly pieces that were created using traditional firing techniques. Understanding the causes and mechanisms of spalling is essential for preserving and maintaining these cultural artifacts for future generations. By taking steps to prevent spalling from occurring and using appropriate repair techniques when necessary, we can help to ensure that these important pieces of history continue to be appreciated and admired for years to come.

One thing to note is that Spalling can occur even years after the piece is made. We've had pottery start spalling months or years after we purchased it!