Atlas Streak Analyzer

The function of the Atlas Streak Analyzer is to isolate barré caused by physical differences. A fabric swatch is combined with polystyrene sheet film, and the Atlas Streak Analyzer produces a plastic impression of a fabric surface by incorporating specific conditions of pressure and heat. The absence of color on the plastic impression ensures that only physical streak effects will be seen. The plastic impression is examined to determine whether the streak alignment matches the streaks observed on the fabric. However, impressions made from spun yarns such as cotton can be difficult to read due to the inherent yarn variation characteristic of spun yarns. Also, a too rapid cooling of the test specimen after making an impression can produce a moiré pattern. From a valid plastic impression, the barré source can be identified as:

1. physical with all streaks showing on the impression,
2. optical or dyeability variations where none of the color
streaks are aligned on the impression, and
3. a combination of physical and dyeability differences where some streaks align with those on the impression, and some do not.


Fabrics with combination causes present the greatest challenge for analysis.

If the streak analyzer indicates the same barré pattern as seen in the fabric, then the barré stripes are physical in nature. This can relate to several physical causes such as yarn tensions, stitch length, yarn count, twist differences, etc.

Yarn tension causes can be found by raveling adjacent courses and measuring the lengths of yarn removed from each course. If all the lengths raveled from the fabric are the same, the pieces can be weighed to determine if the yarn counts are the same.

If the plastic replica shows no stripes, then the barré is due to chemical causes or to light reflectance differences. Chemical causes relate to improper preparation, and light reflectance differences relate to non-uniform dyestuff penetration or reflectance. The next step is to remove the color and evaluate the stripped sample before re-dyeing to determine if the removal of dye was complete and if the barré is still present. An uneven or incomplete stripping can indicate an additional strip. If the color is stripped uniformly and the barré is gone, then the sample should be re-dyed. If after stripping and over dyeing the fabric no longer has barré, then the barré was caused by improper preparation. If the barré remains, then the problem is related to optical or light reflectance problems.