## 2 Materials and Methods
### Carpet Dyeing Process
#### 2.2.2 Dyeing  
In order to dye the carpet samples, the batches were first wetted with a water detergent solution for 30 min at 43 \({}^{\circ}\)C (110 \({}^{\circ}\)F). 2.5 mL detergent was mixed in 10 L of water for each pound (453.6 g) of carpet samples. For three different shades, the dye solutions were prepared according to Table 3. For immersion dyeing of the wool carpet samples, two acid dyes (hue: red and green) were considered in three different shades (saturation): light, medium, and dark. Corresponding dye Color Indices (C.L) are Acid Red 151 (26,900) and Acid Green 3 (42,085). The dyes belong to \"Nylomine\" group. [PERSON] and green dyes have been considered as they are commonly used colors.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{3}{*}{**Carpet Type No**} & \multirow{3}{*}{
\begin{tabular}{c} **Average** \\ **Sample** \\ **Weight** \\ \end{tabular} } & \multicolumn{2}{c}{**Scouring**} & \multicolumn{2}{c}{**Bleaching**} & \multicolumn{2}{c}{**Neutralizing**} \\ \cline{3-8}  & & **Water** & **Sodium** & **Carbonate** & **2.5 mL/lbs** & **Sodium** & **Detergent** & **Hydrogen** & **White** \\ \cline{3-8}  & & & **2.5 gm/lbs** * & **2.5 ml/lbs** & **68 gm/lbs** * & **2.5 mL/lbs** & **Peroxide** & **Vinegar** \\ \hline
1 & 75.5 gm & 0.67 L & 0.33 gm & 0.42 mL & 11.39 gm & 0.84 mL & 41.88 mL & 27.63 mL \\
2 & 62.8 gm & 0.55 L & 0.27 gm & 0.35 mL & 9.35 gm & 0.69 mL & 34.38 mL & 22.69 mL \\
3 & 84.33 gm & 0.74 L & 0.37 gm & 0.46 mL & 12.58 gm & 0.93 mL & 46.25 mL & 30.53 mL \\
4 & 85.97 gm & 0.76 L & 0.38 gm & 0.47 mL & 12.92 gm & 0.95 mL & 47.5 mL & 31.35 mL \\ Total & 308.6 gm & 2.72 L & 1.35 gm & 1.47 mL & 46.24 gm & 34.01 mL & 170.01 mL & 112.2 mL \\ \hline \hline \end{tabular}
* Powdered chemicals were measured in gm scale as per batch weight in lbs.
* 1 gm = 0.0022 lbs.  
\end{table}
Table 2: Amount of Chemicals required for the scouring and bleaching process for a single batch.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Shade** & \multicolumn{2}{c}{**Light**} & \multicolumn{2}{c}{**Medium**} & \multicolumn{2}{c}{**Dark**} \\ \hline \multirow{3}{*}{**Chemicals**} & **Water** & **Dye** & **Water** & **Dye** & **Water** & **Dye** \\  & **250 mL/lbs** & **1.2 gm/lbs** * & **250 mL/lbs** & **4.5 gm/lbs** * & **500 mL/lbs** & **9 gm/lbs** * \\ \hline Required amount & 169.9 mL & 0.816 gm & 169.9 mL & 3.06 gm & 340 mL & 6.12 gm \\ \hline \hline \end{tabular}  
* Powdered chemicals were measured in gm scale as per batch weight in lbs.
* 1 gm = 0.0022 lbs.  
\end{table}
Table 3: Amount of chemicals required for preparing the dyeing solution for one batch of carpets. Corresponding batch weight \(\approx\) 308.6 gm.  
Water, white vinegar, common salt, and the prepared dye solution were mixed together to prepare the dye bath. Required amounts are shown in Table 4. The resultant dye concentration in the dye bath has been charted in Table 5 for gradual shading from light to darker shades. The previously wetted batches were immersed in the dye bath. The temperature of the dye bath was raised to the boiling point and stirred from time to time for 60 min. Additional white vinegar (Table 4) was applied to improve the dye take-up of the batches. After 60 min., the dye bath was cooled to room temperature. The samples were removed from the dye bath, rinsed with water, and air dried.  
A total of 24 colored samples resulted from the dyeing process. Each carpet type was dyed in two hues for three different saturations, yielding 2 \(\times\) 3 (6) dyed samples. As four different carpet qualities were considered, 4 \(\times\) 2 \(\times\) 3 (24) colored samples were evaluated in the following steps. Figure 1 depicts the carpets images for dyed and undyed conditions taken under CWF illuminant.