In addition to the load, one must take into account the weight of the shovel itself so a big shovel should be used when the material is light and a small one for heavy materials. For fine-grained materials the shovel should be slightly hollow, spoon-shaped with a pointed tip for penetration. For coarse materials, the cutting edge should be straight and the blade flat, with a rim round the back and sides. For stiff materials such as clay, the cutting edge can be either straight or pointed but the blade should be flat. The handles of spades and shovels should be 600-650 mm long.