A very great deal in the coach-making industry depends upon the selection of materials. Ash is the kind of wood required in the framework both of body and carriage. The quality best suited for the body is that of full-grown mild and free nature; for the carriage that which is strong and robust; that for carriage-poles should be of younger growth, straight and tough in quality. An important consideration is the seasoning of this timber. Planks of various thicknesses are required, varying from 1½ in. to 6 in., the time required for seasoning being one year for every inch of thickness. After the framework is made, the body is panelled with ¼ in. mild Honduras mahogany, plain and free from grain, every joint and groove carefully coated with ground white lead to exclude water. The roof is covered with ¼ in. wide pine boards, unless when superseded by an American invention, by which, in order to obtain the needful width frequently of 5 ft. or upwards, boards are cut from the circumference of the tree, instead of through its diameter; three thicknesses of very thin wood are then glued together under pressure, the grain of the centre running across the outer plies, the whole forming a solid covering without joints. Birch and elm of 1 in. thickness also enter into the construction in many carriages; for floor and lining boards pine is the material used.
Wheel-making is a very important branch of the business, in which, owing to the increased lightness now required, many modern improvements have been introduced. The timber used in an ordinary carriage wheel is wych elm for the naves, heart of oak for the spokes, and ash for the felloes. American hickory has of late years been also largely used for spokes in exceptionally light wheels, as well as the American method of making the rim in two sections of straight-grained ash or hickory bent to the required circle. This method has much to recommend it, more especially for wheels with indiarubber tires, in which the wood felloes are not required to be nearly so deep as for steel tires. One well-known feature in light wheels is the "Warner nave," which is a solid iron casting with mortices to receive the spokes, and being of small diameter gives the wheel a light appearance.