No, I’m not talking about manicures.
With fiber, the cuticle is the outer layer of the hair which consists of dead cells that overlap in layers that form scales. The scales are uni-directional, point away from the skin and provide strength and structure around the shaft of the fiber. The cuticle is armor for your hair.
With hair and fur, the cuticle scales are heavily layered, but with wool the scales are barbed and usually only one to two scales deep. Research hypothesizes that the scales have something to do with why wool felts much more easily than hair or fur.
Think About This…
What happens when you backcomb your hair from the tip toward the scalp? You look like you belong in a 1980s music video, right? When you brush against the direction of the cuticle, it causes the scales to rise. This can damage hair as the raised scales never lay entirely flat again and begin to break off over time. Because these scales contribute to the structure of the hair, damage to the scales can cause hair to break and split.
Scales and Luster
Luster describes how fibers reflect light. The fewer scales, the shinier the fiber. For example, most long-wool breeds have large, flat scales that make the fiber coarser, but shinier. Fine wools like Merino have a matte appearance because the many small scales reflect light in different directions. Silk, which is an extruded fiber, has no scales which means there is nothing to disrupt the reflection of light. Silk is one of the most lustrous fibers available.
| Wool + Moisture + Heat + Agitation = Felt
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So why does this formula work? Heat and moisture cause the scales on the wool to open up. Agitation and the more open scales contribute to Directional Field Effect (DFE). When wool fibers are pulled against the scales on each other’s surfaces, the scales interlock with one another by means of frictional force, creating a tightly bound mass of fibers that we lovingly call felt.