Measurement Standard
Technical specifications for the determination of fiber diameter using a projection microscope are established by this global document. Adherence to iso 137 ensures that laboratories across different countries produce comparable data for wool and other animal fibers. The method provides a manual reference against which automated systems are often calibrated.
Testing Procedure
Operators measure the width of individual fiber images projected onto a screen at a specific magnification. A minimum of four hundred fibers is typically required to achieve a statistically valid mean. This direct visual approach allows for the exclusion of debris or damaged fibers that might confuse an automated sensor.
Detailed records of each measurement form the basis of the diameter distribution report.
Specimen Preparation
Samples are prepared by cutting short snippets of fiber and mounting them on a glass slide with a suitable medium. Uniform dispersion is necessary to prevent overlapping, which would hinder the clear view of the fiber edges. Evenly distributed snippets allow the technician to move the slide systematically without measuring the same fiber twice.
Applicability Limit
While highly accurate, the method is labor-intensive and slower than modern electronic alternatives. It remains the primary reference for settling disputes or verifying the fineness of very small samples.
