It is not good to have sesame spots on the tile base. There are sesame dots at the bottom, which means there is a problem with the tile and it can no longer be used. The floor tile base refers to the base under the glaze. To measure the quality of ceramic tiles, you can try looking at the base. If the base has many sesame spots, the quality is not good. In addition, there is another way to check the quality. Look at the edges of the base. If the colors on both sides of the base are different from the middle, it basically means that the base is not burned through and the quality is not good.