There are several problems with the seal ink commonly sold in small flat tins or in small, shallow ceramic bowls. First, since the ink is flattened out, the only way to use it is to stamp the seal straight up and down into the seal ink. Because the ink is usually a bit sticky, this can pull small clumps of inky fiber away from the seal ink as you lift the stone. These unwanted bits can make for a fuzzy seal impression when stamped on your artwork. Another problem with flat seal ink is that as you use it the natural tendency is to press the seal down into the center of the ink pad. This is good practice in that, by avoiding the edges of the container, you are less likely to damage the seal itself but, with ongoing use, the center of the seal ink will gradually be pressed down lower than that around the edges. With this depression in the center of the ink it becomes hard to get ink evenly over the face of the seal, resulting in a seal impression with dark well-inked edges and a light under-inked center. Also, by constantly using the center of the seal ink pad it becomes dried out before the edges do. The solution is to use a larger container and roll your seal ink into a ball.
Written by Lu