2.1.1. Materials Commercially scoured-bleached 100% cotton knitted single jersey structure fabric having areal density of 175 grams per square meter was collected from “HI-FASHION COMPOSITE TEXTILES LTD”, Joydeppur, Gazipur, Bangladesh. Following table 1 depicts the color co-ordinates of the cotton knitted fabric that used for this investigation.
2.1.2. Dyes & Chemicals Banana floral Stem (Musa sapientum) was collected from Santosh, Tangail-1902, Bangladesh used as natural dye. ISO Standard Soap without optical brightener collected from James heals, England had used for removing the unfixed dye from colored sample surface.
2.2.1. Dye extraction Banana (Musa sapientum) floral stem were separated from banana pseudo stem and washed. Fresh floral stem were cut into one meter pieces using cutlass and then sliced. Sap was extracted from sliced floral stem by roller squeezer machine. Sap mixture was filtrated by a nylon strainer. The sap solutions were stored in transparent plastic containers. Sap was kept in a cool place and was prevented from sun rays to avoid evaporation and possible reaction.
2.2.2. Sampling Samples dyed at 60, 70, 80, 90, 100 and 1100 C were identified as A, B, C, D, E and F.
2.2.3. Dyeing Dyeing had carried out according to exhaust method by Infra-red lab sample dyeing machine (XIAMEN RAPID, China) for 60, 70, 80, 90, 100 and 1100 C respectively at 60 minutes. Then the dye bath was cooled at 400 and samples were washed at room temperature. Samples were squeezed and air dried in flat dryer machine (MESDAN, Italy).Then soaping was performed for removing unfixed dye form the fabric surface by 0.5 g/L ISO standard soap at 80 0 for 10 minutes. For both dyeing and soaping material to liquor ration had kept 1:20.
2.2.4. Color Coordinates Dyed Fabric Based on the CIE Lab system the color coordinates of the dyed samples were determined via dual-beam reflectance Data-color Spectroflash SF 650X (USA) keeping the setting: Illuminant D65, Medium area view, Specular included and CIE 1964 supple-mental standard observer (10° observer). Each sample was folded twice to give an opaque view with four plies and the color coordinates value was measured automatically.
2.2.5. Determination of Degree of Color Levelness Data color spectrophotometer with specified setting, the degree of levelness of each dyed sample were measured considering the reading-1 as standard and other nines as sample batches. Data for each batch are analyzed with respect to color difference, ΔE value. ΔE is a single value that takes into account the differences between the L*, a* and b* values of the sample and standard in the CIE L*a*b* color system. The Equation 1 was used to calculate the ΔE value.
2.2.7. Determination of Brightness Index Brightness index was measured as per the standard (ISO-2470-1977) method using following relationship (Equation 3) after measuring the reflectance value of the corresponding sample by Data color spectrophotometer according to specified setting only specular excluded was set. Each sample was folded twice to give an opaque view with four plies and the reflectance value was measured automatically.
Brightness index = Refletance value of the substrate at 360 nm / Reflectance value of white diffuser or white tile at 360 nm
2.2.8. Determination of Color Fastness Evaluating various color fastness properties of the selected dyed fabric standard methods was employed. Color fastness to wash, rubbing (dry and wet), light, water, perspiration, was accessed by using grey scale of color change and staining according to ISO 105-C06:2010 [19], ISO-105x12:1995 , EN ISO 105-E01:2013, ISO 105-E04:2013 and EN ISO 105-B02: 2013 correspondingly.