Meller Optics Inc. has announced a line of optical lapping pitch made from wood resin rather than from petroleum by-products. The pitches provide a fine finish and prevent contamination of the polishing media or substrate. Five grades -- from very soft to very hard -- are available, as are melting points ranging between 52 and 87 °C. The company says that different batches are extremely uniform and that the hardness grades are all compatible. The pitch comes in 1- and 5-kg containers and requires no screening, filtering or additives. The user slices the required amount, melts it and pours the lap.