## 2 Materials and Methods
### Fibers and Yarns  
A volumized yarn is the starting point for the design of the new class of fabrics called T4 Innovation. The raw materials selected for this purpose are two: (1) mercerized wool (WV), treated in tops with polyamide (PA) fractions (usually 80-20 percent percentage points) and (2) 100% pure synthetic PA. Both raw materials were tested to verify their compliance with the strict requisites defined in Table 1.  
A fiber fineness (or transverse length) measurement was performed using a projection microscope (lanameter) for both the WV-PA mix and 100 percent nylon. The microscope used has a fixed magnification of 500\(\times\), so that each interval in the screen corresponds to 0.002 mm. In measurements on ribbons or wicks of parallel fibers, sampling is carried out by cutting off the external parts and pushing the remaining pieces onto the slide using 0.4-0.8 mm punches. This allows preventing the fibers from being arranged with the major axis of their cross section in the slide plane, thus distorting the measurement (longer sections due to the natural curl of the fibers, which is greater for the finer ones, are arranged more randomly). In the case of staple material, the specimen is formed by cutting the fibers with scissors in lengths between 0.5 and 1 mm. Selected wool fibers resulted in fineness averagely equal to 26 \(\upmu\)m with a Coefficient of Variation 1 (The CV is the standard deviation SD divided by the mean fiber diameter \(\times\) 100. CV measures the fiber diameter variability as a percentage. CV tends to fall in the range of 15% to 30%, with 15%being uniform wool, whilst 30% is highly variable wool.) CV equal to 25.4%. Nylon fibers have an average diameter of 18 \(\upmu\)m. Since such values fall in the range of workability of fibers, authors consider such selected raw materials the elective starting point for creating the yarns to be used for weaving the innovative fabric. Moreover, the measured CV for wool can be considered a typical value for volumized fibers. After a number of attempts, it was decided to use, for the weft yarns, the wool-nylon mix while warp yarns are instead entirely composed by Synthetic Polyamide (nylon). As far as the wool-nylon mix is concerned, it was necessary to act on the production process of the yarn. In particular, since the carded spinning is carried out with fibers of 40-50 mm while the new fibers to be processed are much longer (i.e., \(>\)70 mm), it was necessary to modify both the unraveling operations of the mixed fiber and of the cylinders in the ring-spinning machine. To this aim, the wool-based yarn is obtained by using a modified ring-spinning machine [17]. Such a system (shown in Figure 2) consists of a double roving unit capable of supplying both the core fibers (nylon) and the natural fibers wounded on such a core. Thanks to this double feeding mechanism, the volumized yarns are created without further processing, since one of the roving fibers (i.e., the left one in Figure 2), continuously fed, provides the synthetic fibers, while the other provides the wool fibers. Since two spinning-fed rovings are used, no twisting is required to add nylon as the core of the yarn. This is added directly during the spinning phase. The subsequent twisting, which still occurs with double twist S-Z, allows a percentage of 4% of 50 DEN yarn to be added to the yarn core. The final composition of the yarn is given by about 67% wool and 33% nylon. In addition, at the end of the double stretch phase, the yarn is characterized by open fibers conferring a suitable volume; therefore, after spinning, the yarn does not require a vaporization phase. Figure 3 shows a comparison between a typical yarn obtained by conventional ring spinning and the volumized one obtained with the new ring spinning system of Figure 4. It should be mentioned that both yarns are not handled with a cycle of steaming. Figure 2: Scheme of the new ring spinning system provided with double drafting unit.