If a player uses water on clay, soft clay is created, awarding the player with 1 Crafting experience. As of 15 February 2011, players no longer need a container for the water, meaning soft clay can be made directly at a water source. This is used to make pottery in Crafting, Urns, furniture in Construction and Magic tablets.
Players can get 200M experience by mining exactly 40,000,000 clay without bonus experience, generating a profit of 13,160,000,000 at the current Grand Exchange mid price.
Some players find that mining clay is a good way to make money on F2P servers.
Training Mining with clay from level 1 to 99 would require a total of 2,606,887 pieces of clay be mined, which would turn a profit of 857,665,823 coins (at the current market price). It takes about 1 minute to mine 28 clay using a rune pickaxe and about 1 minute to bank and return so this means about 840 clay per hour, for a total of 3,104 hours of work.
If the player uses a suitable filled container on dry clay while being within two squares of a water source, they would automatically refill the container and the player could soften all clay in one go, although it is simpler and faster to use the clay on the water source.