When you buy a Teapot, you may notice black patches or streaks on the body, causing uneven coloration. This is known as the “patchy mud” phenomenon. What causes this?

The clay used for making the teapot has been stored for too long without being reconditioned before use. After prolonged storage, organic matter in the clay forms soluble sulfates that appear on the surface of the clay. If this particular piece of clay is used to make a teapot, a dark discoloration will appear after firing, resulting in patchy mud.

After shaping the Purple Clay Teapot and allowing it to air-dry, if it isn't fired promptly and is left for too long, a glaze will form on the surface. When fired, this can also result in the patchy mud appearance.

Another scenario occurs when the potter switches clays. For example, if they are about to work with purple clay, they must thoroughly clean their workspace and tools to prevent any residual clay from the previous batch from contaminating the new clay. If other types of clay mix into the purple clay, it can cause patchy mud.

During the process of shaping the body of the teapot, if the potter's skills with the scraper aren't adequate or the pressure isn't applied evenly, dents can appear on the body. Alternatively, if the unfired teapot is too dry when being polished, uneven angles can cause the polishing tool to slip, leading to patchy mud after firing.

There are many causes of patchy mud. At lower firing temperatures, it may not be noticeable, but at higher temperatures, it becomes more apparent after vitrification. If the clay is dark in color, the patchy mud may gradually disappear after the teapot has been steeped and cared for over time.