Fabric Dissection To perform accurate fabric dissection analysis, a fabric sample that contains several barré repetitions is required. First, the barré streak boundaries are marked by the placement of straight pins and/or felt markers. Individual yarns are removed from light and dark streak sections, and twist level, twist direction, and cut length weight determinations are made and recorded. For reliable mean values to be established, data should be collected from at least two light/dark repeats. After compilation of yarn information, the numbers can be compared individually to adjacent yarns as well as by groupings of light and dark shades.
Microscopy Microscopic examination is useful for verifying yarn-spinning systems. Yarns from different spinning systems can have different light reflectance and dye absorption properties resulting in barré when mixed. Ring-spinning produces yarn that is smooth with all fibers twisted in a tight helix. Open-end spinning produces yarn with wrapper fibers that form a belt around the diameter of the yarn at irregular intervals. Air jet spinning produces yarn with more wrapper fibers that form a continuous spiraling band around the inner fibers that are more parallel to the axis of the yarn. Microscopy can also reveal a shift in loop formation in knitted fabrics when twist direction (S and Z) differences are present.
