How cotton thread is made: from bud to spool - part 2

Continuing on from our thread production part 1 article we are reaching the part in the production where the cotton is becoming thread as we know it.
 

Plying and Twisting the Cotton


Threads consist of two or more yarns which are combined in the plying process ready for the subsequent twisting process.

Twisting is the actual twisting of yarns to make a thread. The plied yards are twisted around their longitudinal axis, and thus closely connected. The compactness increases the strength and determines the sewing performance.

There are two distinct twist directions that may be simply referred to by the letters S and Z. Single yarns are usually twisted in the S-direction while threads twist in the Z-direction.
 

 

Dyeing the Cotton


In this production step, all threads are wound onto dye packages. The hollow spindles are perforated so that the dye bath liquor can flow through the package, from the inside to the outside and vice versa.

The goal is to achieve an even colouring of the sewing and embroidery threads, regardless of their position on the dyeing spindle.

The selection of the dyeing method is mainly determined by the thread's raw material. Cotton and polyamide, for example, require different methods than polyester. Polyester threads are dyed using the high temperature (HT) method.For Polyester/cotton core spun threads it is necessary to consider two dyeing methods due to the raw material combination of polyester and cotton. Within a single process, but with two subsequent steps, the polyester is dyed first and then the cotton.Pure cotton threads are often dyed in hanks, for which special dyeing machines are required.


 

Finishing the Cotton


Sewing and embroidery threads must be lubricated, i.e. finished with a slipping agent, in order to assure an optimal sewing performance. The exact formula is the secret of every sewing thread manufacturer.

The lubrication is applied in the dyeing machines immediately after the dyeing process, or after the dyeing in separate machines. The selection of the suitable method is determined primarily by sewing thread's linear density and its type.


Special Finishing Processes


Gassing or Singeing

In the gassing or singeing process, the fibre parts that stick out are burnt off. The surface of sewing threads which are made of spun yarns is smoothened with this finishing process.

Polishing and Dressing

Polyester/cotton core spun threads and pure cotton threads are partly polished or dressed in order to give them a more enclosed and smoother surface, and to increase their abrasion resistance. In this finishing process, the dyed threads are dipped in starch or a synthetic wax preparation, and then brushed. Thereby, fibre parts that stick out are brushed in one direction to make them cling to the yarn surface.

Mercerisation

Mercerisation is a process applied to cotton thread and others. It is done after spinning to increase lustre.
In addition to increasing lustre and affinity, the treatment increases strength, smoothness, resistance to moisture, and also reduces lint.  So higher quality threads and fabrics, for example, are always mercerised.


                                
 
 

Make Up


In the winding department the finished threads are wound in the different make-up styles (spools, cones, king spools, etc.).

The make-up style (shape and size) must be matched to the different sewing threads, their properties as well as the sewing machines.