* Lead shrinks when it cools, which can distort your letters, but adding some tin and antimony produces an alloy that shrinks less and is harder once set. Different printers use different ratios, but a mixture of 54 percent lead, 28 percent antimony, and 18 percent tin was used traditionally, with a mixture of 78 percent lead, 15 percent antimony, and 7 percent tin being used for more durable type intended for longer print runs.