The most common painted mark material used on early pots was a slip containing cobalt, resulting in a blue mark when fired. Other mixtures contained different minerals, including manganese and titanium, which resulted in red, yellow, and other colors, depending on what was mixed into the slip. Stamped marks are applied with a rubber stamp dipped into a cobalt ink-like solution and pressed onto the surface of the pot. These, like stenciled marks, are uniform in style and content, but often are difficult to read or partially smeared because the potter had to use a rolling action of the flat stamp on the rounded surface of the pot. These marks are not a part of the glazed and fired pot, but are applied after the pot is finished.
Molded marks appear in pottery that was made in a jigger mold or was slip cast.
The most common molded marks can be found on the bottoms of vessels, and can be either convex or concave. Some of these marks can be quite elaborate, since no extra work is required of the potter once the mold has been made. Nothing helps the collector more than a maker's mark on a pot. When a pot carries the name or initials of the potter incised, impressed, painted, or stenciled under the glaze, there can be no doubt about its provenance. Maker's marks run the gamut from a simple inscribed letter to complex stenciled logos.