New patterns and grades should be tested for shrinkage as soon as the goods come from the loom, as short lengths made in sample looms are not at all times reliable. Frequent tests are also advisable to see that original conditions are maintained, as changes made by heat, steam and speed are always liable to occur.
The immersing process is used mostly for single cloth garter webs. Double cloth webs having a warp pile on the face are sized on the back only. Exceptions are made on double cloth white webs used for the corset trade, which are bathed with a very light size and often tinted in this bathing process to the desired tone of white to match the cloths they are to be associated with. Where the goods are sized on the back only the effect of this has to be considered when they are constructed, and provision made to maintain a proper balance under such conditions.
In frilled webs the elastic portion only is sized, so as not to interfere in any way with the soft flutings of the frill. This is done by guiding each strip over narrow pulleys which are run through the size bath. The size accumulated on these pulleys is absorbed by the web passing over them.
Acid in Goods
The requirements of the trade are so varied, and the types of web so numerous, that no formula for size is suitable for general use. Care must be taken, however, to avoid any sizes containing acids. Results from the use of such preparations may seem excellent at the machine but later on, when the goods are made up and come in contact with metal parts, the metal is quickly tarnished, and the result may be heavy claims for damage.
It may be well to note here that the sulphur used in the process of vulcanizing the rubber has the effect of blackening the copper cans and the rolls over which the goods must pass. This can be effectively prevented by having the cans nickel plated, thus doing away with much risk of dirty goods, and of constant scourings and washing of the different parts.
Fig. 4.—Narrow Fabric Singer
Provision should be made for sufficient depth in the sizing pans so that they will hold a liberal supply of size. Replenishment should be made at regular intervals and the heat maintained at a uniform temperature to get satisfactory results. It is advisable to make provisions to travel the web over the top of the machine for a distance after immersion in the size bath, and before it strikes the hot cans, so as to allow for proper absorption of the size.