What process is used to make earthenware waterproof?

The process used to make earthenware waterproof is glazing. Glazing involves applying a glass-like coating to the surface of the pottery, which not only enhances its visual appeal with color and textures but also creates a non-porous barrier. This barrier keeps liquids from being absorbed by the clay body, making the finished piece functional for containing liquids without leaking. During firing, the glaze chemically bonds with the clay body, resulting in a durable finish.

Other processes, like sealing, are generally applied after the glazing to provide additional protection or aesthetic finish but do not inherently make the pottery waterproof on their own. Coating refers to covering an object with a substance, but without the properties of a glaze, it may not provide the same waterproof benefits. Firing is crucial for hardening the pottery but does not render it waterproof without the application of glaze. Thus, glazing is the specific process that effectively ensures the earthenware is waterproof, fulfilling its functional use.