On account of the great and enormous strain put upon belting, and the necessity for its running true upon the pulley, it should be of the highest grade possible, combining great strength to prevent stretching, and evenness of grain to insure long wear; therefore only hides of selected steers are serviceable, and these in turn are rejected when they contain any blemishes or cuts or other imperfections. After a hide is accepted for belting purposes, it is subjected to a generous trimming, the head, neck, legs, and belly being cut away, leaving only a small and compact section embracing from two to two and a quarter feet on each side of the backbone and extending about six feet along the same from the tail forward. This is the portion of the hide where the fibers are closely and firmly knit together, and where the vitality is the greatest, due to the close proximity of the network of nerves radiating from each side of the spine to all parts of the hide.
The hides of the bull and cow of every breed are inferior for belting purposes to that of the steer. The hide of the bull is coarse and hard, with the neck very heavy and full of wrinkles, causing a variation in the thickness and run of the grain of the leather. The hide of the cow is thin, does not run uniform in thickness, being heavier on the hips than at the shoulder, and is lacking in the firmness necessary in good belting. The sharp angles of the hip bones of a cow also tend to form pockets in the hide.
After the hide has been trimmed, it is subject to the process of “currying.” All membranes or particles of flesh adhering to the hide are removed by a machine which shaves the membrane, etc., off, with lightning rapidity. The leather is then washed and scoured by machine, which removes all dirt still adhering to the hide. After the leather is thoroughly cleaned and while in a damp state, it is placed upon the table, and greases, composed of pure animal oil, are worked into the leather on both the grain and the flesh side with brushes. This is carried on in the cold state. It is then put into a large revolving wheel containing water heated to a high degree, which causes the leather to swell and pores to open. The leather is then taken out and put into another wheel containing heavy mineral oil and heated several degrees greater than the water, and tumbled about in the wheel until the heavy oil fills the distended pores and fibers. After this, the leather is allowed to dry.
The hides are allowed to remain for several months in the tan liquor until the green hide is changed into leather.
After the hide has been changed into leather, it is stretched. To properly stretch the leather for belting purposes, it must first be cut so as to remove that part which shows the markings of the backbone of the steer.
Leather is stretched by placing it in clamps, every part of the piece getting the same pull. (The leather is put into the clamps while damp, as damp leather will give the greatest amount of stretching.)
When the stretching process is completed and the leather has thoroughly dried in stretching clamps, it is released. These pieces of leather are quite dry, very firm, and not very pliable. The leather is now moistened in order that it shall be more pliable as it passes through the finishing processes. After the water has soaked into the leather (called sammied), it becomes very soft. It is then subjected to a roller under heavy pressure to take all the unevenness out of the hide. It is next thoroughly dried, causing the fibers to shrink; then again moistened and put through a polishing machine, which acts on the same principle as the rolling jack.
The sides and centers are now put through a cutting machine, which reduces the leather to strips of different sizes.
Belts are put together by cementing the parts. Belt cement is a most powerful adhesive. It actually governs the strength of the belt, as the belt is as strong as the weakest part of the joint.