Making Warps for Elastic Fabrics—Quills for Use in Shuttles—Effect of Finishing Processes Must Be Calculated from Beginning of Web Construction—Details of Processes and Machines for Different Styles of Goods—Care to Avoid Acid in Goods—Rubber’s Reaction on Copper
The making of cotton warps for elastic fabrics, particularly for double cloth webs, involves considerable thought and care in view of the number of sections necessary for a properly constructed fabric, and the different weaves employed. Owing to the contraction of the rubber, it is essential at all times that the proper balance be maintained between the face and the back of the goods.
This necessitates a uniform weight of stock where the weaves on the face and the back are identical, no matter how the size of the yarns used may vary, and a variable weight of stock where the weaves are different. All this is determined by experimental work when establishing the grade. These conditions necessitate separate warps for the face and back. Then again the different weaves employed involve a variable length in the take-up and this alone would make it impracticable to combine the various weaves.
It is invariably the plan to use fine stock for the face and a coarser material for the back. Of course it would not be practical to put these together on the same beam. The crowded condition of material used necessitates the further splitting of the face and back sections. The binder, which takes up so much faster than any of the other yarns, also requires a special warp.
Selvage Under Special Control
The general appearance of the finished product being so dependent upon the character of the selvage, it is advisable to have these threads under special control, so that they may be treated in the best possible manner to produce a satisfactory shed, and allow the filling to get a good clearance. So as to secure a smooth well-rounded edge it is therefore necessary to have this on a special beam.
It will be seen, therefore, that in an ordinary piece of double cloth elastic web there will be required at least five warps: back, face, binder, edge and gut. Figures and fancy effects will often necessitate auxiliary warps. With very fine webs, having six threads to a cord, it is often found necessary further to split up the face to obtain proper working conditions. Figs. 1 and 1A show a six-cord web, together with warp calculations for the goods.
The employment of so many warps to each strip of web, which are automatically delivered by the friction let-off levers described in a previous article, prohibits the use of warps where the threads are equally distributed across the beam, as is the practice in wide fabrics, the method usually being to tape them on the beams.
Warping Machine
The required spools for the number of threads in the warp are put in a creel, each thread passing under an electrically connected wire, which is held out of contact by the running thread while the warp is making. If the thread should break, the wire would drop and make an electrical connection which would automatically stop the machine. Fig. 2 shows a view of a warping machine such as is used for this work. They are generally constructed so as to allow for two or four beams, all of which may be run together or started, stopped or run individually, as required.