Bottle kilns were used for firing earthenware and porcelain products, as well as bricks and drainage pipes. Each firing would take several days from when the kiln was first stacked with the various products and then the fires were lit. The temperature then had to be carefully controlled throughout the process and, after the firing complete, the stack had to be allowed to slowly cool before it could be removed. Set several kilns alongside an industrial track, add some suitable buildings, unload coal and clay, load up the finished products.