## 2 Materials and Methods
### Technical Requirements  
With the aim of designing the T4 Innovation fabric, it is necessary to state a number of technical requirements based on the typical performance of winter fabrics required to act as thermoregulatory clothing. Such requirements are specified for both fibers and yarns composing the fabric, and for the fabric itself. Referring to fibers, there are no particular restrictions in terms of mechanical or thermal performance. Rather, it is strictly required to guarantee the absolute absence of heavy metals and of tetrachlorophenol (see Table 1) according to Oeko-Tex Standard. The technical requirements for yarns are in Table 2. The most important parameters to be controlled are the volume and composition of the yarn. In fact, it is desirable to create a fabric with a consistent amount of wool with high density. The most important requirements are, therefore, on the manufactured fabric--once verified that the fibers and yarns comply completely with the above-mentioned technical specifications, fabrics must meet the following technical requirements: \begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameter** & **Standard** & **Requirements** \\ \hline Heavy metals (antimony, arsenic, lead, cadmium, chromium, cobalt, nickel, mercury, copper) & [[http://www.oecotextiles.com/PDF/](http://www.oecotextiles.com/PDF/)]([http://www.oecotextiles.com/PDF/](http://www.oecotextiles.com/PDF/)) textile\_industry\_hazards.pdf & Absent 1 \\ \hline Tetrachlorophenol & [[http://www.oecotextiles.com/PDF/](http://www.oecotextiles.com/PDF/)]([http://www.oecotextiles.com/PDF/](http://www.oecotextiles.com/PDF/)) textile\_industry\_hazards.pdf & Absent 2 \\ \hline \hline \end{tabular}  
* Limited quantities are allowed by the current standard; maximum permitted limit is 0.5 mg/kg. 2 Maximum allowed limit by normative is 0.5 mg/kg.  
\end{table} 
Table 1: Technical requirements for fibers. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameter** & **Standard/Reference** & **Requirements** \\ \hline Volume & [12] & +8\% with respect to conventional wool yarns \\ Minimum amount of Wool (\%) for & & wool yarns \\ volumized yarn & [13] & 75\% \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Technical requirements for yarns. * Lightness: garments made with the new fabric must weigh little in order to be carried in the backpack or worn. The aim is to create a fabric weighing between 200 and 450 g/m\({}^{2}\) and/or 500-600 denier. * Water-vapor resistance: measured using the ISO-11092, also known as the Ret test [14]. In this test, the fabric is placed above a porous (sintered) metal plate which is heated [15]. Water is channeled into the metal plate, simulating perspiration. The plate is kept at a constant temperature. As water vapor passes through the plate and the fabric, it causes Evaporative Heat Loss and therefore more energy is needed to keep the plate at a constant temperature. Consequently, Ret [m\({}^{2}\)Pa)/W] is the measurement of the resistance to evaporative heat loss. The lower the RET value, the less resistance to moisture transfer and therefore higher breathability. Generally, softshell garments have Ret values from 8 to 13, while Gore-tex or Gore-tex-pro have Ret values from 4 to 6. The objective of the new fabric is a Ret from 4 to 8. * Waterproofing: water-repellent garments have the characteristic of being waterproof to a modest level of rain. Water repellency is evaluated according to UNI EN 24,920. The water repellency value is given with an ISO index from 1 (lowest) to 5 (best). The objective for the new fabric is an ISO 3, 4 index. * UV protection: is the ability of some fabrics to protect the skin from the action of ultraviolet rays. It is measured by the UPF (Ultraviolet Protection Factor) [mJ/cm\({}^{2}\)] for which it is possible to identify good protection with values from 15 to 24 and excellent protection when UPF is greater than 40. Despite the use of the innovative fabric is planned for winter garments, a supplementary requirement for the innovative fabric is its UV protection.