Determine crimp (crimp %) of a given manmade fibre sample

Introduction: Crimp is defined as the waviness or curvature of a fiber along its length. It plays an important role in the mechanical properties of fibers and their ability to be spun into yarns. Crimp percentage is a measure of the degree of waviness or curvature of a fiber and is an important parameter in the textile industry.

Objective: The objective of this lab experiment is to determine the crimp percentage of a given manmade fiber sample.


  • Manmade fiber sample
  • Microscope
  • Stage micrometer
  • Glass slide
  • Cover slip
  • Forceps
  • Distilled water
  • Dropper
  • Paper towel
  • Metric ruler
  • Calculator


  1. Obtain a small amount of the manmade fiber sample and place it on a clean glass slide.
  2. Using forceps, gently separate the fibers and create a thin layer of fibers on the slide.
  3. Place a drop of distilled water onto the fibers using a dropper to prevent the fibers from moving around while observing them under the microscope.
  4. Carefully place a cover slip over the fibers, avoiding any air bubbles.
  5. Place the slide under the microscope and focus the lens on the fibers.
  6. Using a metric ruler, calibrate the microscope by measuring the length of the stage micrometer under the same magnification as the fibers. Record this value for later use.
  7. Observe the fibers under the microscope and identify the crimp waves or curves along the length of the fibers.
  8. Using the stage micrometer, measure the length of 10 crimp waves or curves along the length of the fiber sample. Record this value for later use.
  9. Remove the cover slip and gently blot the excess water from the fibers using a paper towel.
  10. Using the formula below, calculate the crimp percentage of the fiber sample:

Crimp percentage = (Crimp wave length / Fiber length) x 100

Where, Crimp wave length = average length of 10 crimp waves measured using the stage micrometer Fiber length = length of the fibers measured under the microscope using the calibrated metric ruler

  1. Repeat steps 1-10 for at least two additional fiber samples to obtain a more accurate average crimp percentage.

Results: Record the crimp percentage values for each fiber sample tested and calculate the average crimp percentage for the given manmade fiber sample.

Discussion: Discuss the importance of crimp percentage in the textile industry and how it affects the mechanical properties of fibers and yarns. Compare the crimp percentage values obtained for the different fiber samples and explain any variations observed. Suggest further experiments that could be conducted to investigate the crimp properties of fibers in more detail.