On vulcanizing boots and shoes, the shoes are placed on racks supported by iron cars, which are run over tracks into the vulcanizing chamber. This consists principally of a large room provided with a steam coil on the floor. The temperature rarely exceeds two hundred and sixty degrees Fahrenheit. In vulcanizing shoes, the heat is increased gradually from the beginning, about one hundred and eighty degrees Fahrenheit, otherwise the goods would be blistered, due to the rapid evaporation of moisture and other volatile constituents. They are kept in these heaters from six to seven hours. This causes a union of sulphur and rubber, which is not affected by heat or cold.
They are wheeled on another truck to the packing room, where they are inspected, taken from the lasts, tied together in pairs, or placed in cartons, as the case may be. They are then sent to the shipping room to be packed in cases ready to be delivered to the cars waiting at a side track of the railroad, or sent to the storehouse until they shall be called for by the jobbers or retail dealers.
An important branch of the rubber business is the manufacture of tennis shoes. This is a generic term, which is applied to all kinds of footwear having cloth tops and rubber soles. As the name indicates, they were first used in playing the game of tennis, but they have come into very general use as warm weather and vacation shoes, and every year shows an increased popularity. These shoes are made in a similar manner to the rubber shoes, the rubber soles being cemented to the cloth uppers and vulcanized the same as the rubber overshoes. Many different styles are made, and each year shows some improvements in the shapes, in the textiles which are used, in the colors and combinations of soles and uppers.
Rubber shoes should not be expected to give satisfactory service unless properly fitted. If too short, too narrow, or if worn over leathers with extra heavy taps, or unusually thick, wide soles, strains will be brought upon parts not designed to stand them and the rubber will give way. Rubber goods, particularly boots, if too large will wrinkle and a continued wrinkling and bending is liable to cause cracking.
Extreme heat or cold should be avoided. Rubber boots or shoes should never be dried by placing them near a heater of any kind. If left near a stove, register, or radiator, the rubber is liable to dry and crack. If left out of doors in winter, or in an extremely cold place, they will freeze. Then when the warm foot is put into them and the rubbers are worn, the rubber will crack.
Oil, grease, milk, or blood will cause rubber to decay in a very short time. If spattered with any of these, the rubber should be promptly and thoroughly cleaned with warm water and soap.
The oil in leather tops will rot rubber, so that care should be taken in storing and packing to prevent the leather and rubber from coming in contact.
Putting together the Parts of a Rubber Shoe.