Divided into several phases, the dyeing is the working process for the transformation of the raw greige yarn into coloured yarn, through the use of colouring substances. Determining factors are dyeing uniformity, dye penetration and colour stability , it is indeed fundamentally essential that the fabric maintains its original colour over time.
In dyeing the journey of the greige yarn begins.
The process begins with a treatment to eliminate the inherent fibre impurities. Then follows the actual dyeing that takes place in autoclaves (machinery used for dyeing), where has been previously prepared a bath of an alkaline medium, containing various products: dyes, wetting agents (to improve the liquid absorption capacity of a fibre), equalising (to obtain the uniformity of colour on the dyeing packages) and reducing (to activate some chemical processes). The third process is constituted by the washing and oxidation. Two further processes eliminate the excess dye not absorbed by the fibre and carry the dye from water soluble to insoluble.
The dyeing process lasts from 8 to 12 hours, and it is possible to dye simultaneously from a minimum of one to a maximum of 672 dye packages.
The packages are finally dried in two steps: first by centrifugation to eliminate 50% of the water absorbed during the dyeing and then through radio frequency or forced air, to enable the fibre to reach the correct percentage of moisture.
CONTROLS ON THE YARN
The controls on the colour after dyeing are fundamental to verify the uniformity of tone on each package, the colour continuity over time and the colour-fastness to rubbing. Each day around 40/50 dye baths are checked.
Laboratory tests are performed by highly qualified technicians, with state of the art instrumentation and in accordance with all European and international regulations.