Sizing

Sizing is a complementary operation which is carried out on warps formed by spun yarns with insufficient tenacity or by continuous filament yarns with zero twist. In general, when sizing is necessary, the yarn is beam warped, therefore all beams corresponding to the beams are fed, as soon as warping is completed, to the sizing machine where they are assembled. Sizing consists of impregnating the yarn with particular substances which form on the yarn surface a film with the aim of improving yarn smoothness and tenacity during the subsequent weaving stage.

The  following  list  summarizes  the  materials that  can  be used as warp sizes. Some  of  the  base materials are  used either  alone  or as additives to impart  desirable properties  to other  bases. When designing the  desizing  step, it  is  important to  know what base size was used.  Each  film - former  has  its own optimum conditions  for effective  removal.  A  knowledge  of  the  chemistry  of  the  film - formers  will  make it easier  for  one  to grasp  how to best desize  specific  fabrics.

There is not just one sizing  ″recipe ″ which is valid for all processes, on the contrary the sizing methods change depending on the type of weaving machine used, on the yarn type and count, on the technician’s experience and skill, but above all on the kind of material in progress. The only common denominator of the various sizing materials is that they have to be easily removable after weaving in order to allow carrying out without problems the selected finishing cycle.

The substances used as sizing material are potato flour, starches, glues, fats but also talc and kaolin, when a particularly thick size is requested.

Following Figures show two possible processing lines for the sizing machine.

 

 Sizing machine: 1.Size vat; 2.Radio-frequency oven; 3.Drum drying machine; 4.Waxing device;

 5.Beaming.

 

Sizing machine: 1. Size vat; 2.Hot air oven; 3.Drum drying machine; 4.Waxing device; 5 .Beaming.