# Transmission Reduction for UV and IR Radiation with Dyed Lyocell Knitted Textiles
## 3 Results
### Usability of the Dyed Knitted Fabrics
#### 3.3.1 Washing Resistance Analysis  
Washing resistance is an important factor in assessing the usability of textiles for clothing applications. Figure 6 compares the transmission of washed and unwashed textiles dyed with Drimaren Yellow (Figure 6, left) and with Solophenyl Bordeaux (Figure 6, right). \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Sample** & **L*** & **a*** & **b*** & **C*** & **h** \\ \hline
100\% Lyocell, undyed & 84.36 & 1.23 & 6.33 & 6.45 & 79.01 \\ Lyocell with TiO\({}_{2}\), undyed & 90.99 & 1.31 & 4.74 & 4.92 & 74.57 \\
100\% Lyocell, Drimaren Yellow, unwashed & 59.93 & 34.51 & 63.72 & 72.47 & 61.56 \\
100\% Lyocell, Drimaren Yellow, washed & 59.57 & 34.82 & 63.02 & 72.00 & 61.08 \\ Lyocell with TiO\({}_{2}\), Drimaren Yellow, unwashed & 64.80 & 35.01 & 67.77 & 76.28 & 62.60 \\ Lyocell with TiO\({}_{2}\), Drimaren Yellow, washed & 63.03 & 35.71 & 64.37 & 73.61 & 60.98 \\
100\% Lyocell, Solophenyl! Bordeaux, unwashed & 33.89 & 29.70 & \(-\)3.39 & 29.89 & 353.49 \\
100\% Lyocell, Solophenyl! Bordeaux, washed & 36.22 & 28.95 & \(-\)3.79 & 29.19 & 352.53 \\ Lyocell with TiO\({}_{2}\), Solophenyl! Bordeaux, unwashed & 34.57 & 34.43 & \(-\)6.11 & 34.96 & 349.94 \\ Lyocell with TiO\({}_{2}\), Solophenyl! Bordeaux, washed & 35.99 & 33.41 & \(-\)6.48 & 34.03 & 349.02 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: LCH-values of dyed textiles, measured with D65 standard light (before and after washing). The results of the transmission measurement of Drimaren Yellow HF (washed & unwashed samples) can be seen in Figure 6, left. The influence of washing on knitted fabrics made of 100% Lyocell is clearly visible. The transmission is increased in the UV range as well as in the NIR range. The knitted fabrics with TiO\({}_{2}\), on the other hand, are very resistant to multiple washing and show hardly any deterioration in transmission behavior compared to the unwashed sample. In the UV range, the transmission values are minimally increased, but much lower than with knitted fabrics made of 100% Lyocell. For samples dyed with Solophenyl Bordeaux (Figure 6, right), it is noticeable that multiple washing has an influence on the transmission behavior of both materials. The transmission of knitted fabrics made of 100% Lyocell and those spin-doped with TiO\({}_{2}\) is increased after the washing procedure. This is particularly clear in the NIR range, where the difference between the washed and unwashed samples is more pronounced. The washed Lyocell TiO\({}_{2}\) knitted fabric also shows a noticeable difference in the UV range. The transmission in the UVB range is even higher than that of the washed 100% Lyocell knitted fabric. Both washed samples also show a clear difference in transmission in the visible range. Reasons for this could be a partial dye release and a fiber abrasion. The color change occurring due to washing was measured colorimetrically (Table 3). The unwashed sample was measured as a standard and the washed samples were measured in comparison. The CIE \(\mathbf{l}^{*}\)*b\({}^{*}\) values and the \(\Delta\mathbf{E}^{*}\) values for the samples at standard light D65 are shown in Table 3[68]. The measurements show that after the washing procedure, the single color parameters are changed (see Table 2) and that color changes can be determined for all samples. All knitted fabrics dyed with Solophenyl! Bordeaux 3 BLE show an increase in brightness and a less saturated appearance. The knitted fabric made of Lyocell 100% appears slightly  
Figure 6: Transmission spectra of knitted fabrics dyed with Drimaren Yellow (**left**) or Solophenyl Bordeaux (**right**) made of 100% Lyocell and Lyocell with TiO\({}_{2}\). Comparison of washed and unwashed samples. redder, whereas the knitted fabric containing 2% TiO\({}_{2}\) appears slightly bluer. Overall, the color change by washing the pure Lyocell knitted fabric is more intense, which is shown mainly by the increase in the value L\({}^{*}\) (see Table 2).