Gravimetric and Optical Quantification Protocols for Bast Defect Content
Gravimetric digestion provides absolute mass baseline proof for bast defects, while optical scanning provides fast surface area sorting requiring lot calibration.
Shirley Mechanical Analyzer
Mechanical Separation
A specialized laboratory instrument separates trash, dust and foreign matter from cotton or flax fibers using aerodynamic and mechanical forces. The Shirley mechanical analyzer is used to determine the exact percentage of non-fibrous contaminants in a raw fiber sample. This measurement is essential for spinners to assess the cleaning efficiency of their opening rooms and carding lines.
It establishes the baseline quality of the raw material before it enters the spinning process.
Aerodynamic Sorting
The instrument operates by feeding a weighed sample of fiber over a high-speed licker-in cylinder, which opens the clumps into individual fibers. A controlled stream of air then carries the lightweight fiber upward, while the heavier trash particles fall by gravity into a separate collecting tray. This action relies on the difference in density and surface area between the pure flax and the heavier shives or soil particles.
The Shirley mechanical analyzer collects these two fractions with high repeatability, allowing for precise determination of the clean fiber yield.
Purity Calculation
Weighing the separated trash fraction yields a direct percentage of the total contamination present in the original sample. This data helps mills adjust their purchasing prices and configure their carding machinery for optimal waste removal. By runing these tests, spinners prevent excessive machinery wear and maintain yarn quality.