Can you tell the difference between animal fibres such as wool, cashmere, rabbit hair and alpaca hair?

Natural animal wool fibre is an important raw material for the textile industry, of which sheep's wool fibre accounts for 70 per cent of the total 80 per cent. In addition, there are some special animal fibres, such as: cashmere, rabbit hair, alpaca hair, camel hair, mohair and so on. They have a scarce production, unique style, elegant and noble characteristics, is the first choice of raw materials for high fashion.
Some manufacturers in order to attract the majority of consumers, often using sheep wool and special animal fibre blended fabrics. Therefore, effective identification, accurate distinction between wool and other special animal fibres is very important.
Wool and other special animal fibres belong to the same protein fibres, chemical properties of the differences are not great. And only in the scale structure and fibre fineness of some differences, so far there is no effective chemical or physical detection methods.
At present, the main use of various types of animal fibre scale structure of different reflections as the basis for their identification. The main methods include optical projection microscopy, scanning electron microscopy, solution method, staining method and infrared spectroscopy. Among them, the optical microscope method and scanning electron fiberscope method are the more widely mature ones.
Animal hair fibre is composed of many keratinocytes. Its cellular structure is divided into three parts: namely, the scaly layer on the outer surface, the inner cortical layer and the medullary layer in the centre. Coarse hair fibres generally have all three layers, whereas fine hair fibres generally have only the squamous and cortical layers and no medullary layer.
1. Squamous layer
It consists of keratinised keratinocytes, which are encapsulated on the outside of the hair shaft, and is a unique surface structure of the hair fibre. Its main role is to protect the hair fibre from external conditions that cause changes in properties. The root of the scale is attached to the hair shaft, and the tip of the scale extends out of the surface of the hair shaft and points to the tip of the hair, and opens outward to varying degrees, forming a horn. There are basically three types of scale morphology: annular or diagonal stripes, tile-like and tortoise-like. Since the size of each scale is basically similar, for fine hair fibres only one scale is needed to encircle the hair. For coarse hair fibres, it takes several scales to join together to enclose them. Therefore, from the emblem microscope, the fine fibre scales are arranged in a ring-like pattern, while the coarse fibre scales are arranged in a tile-like pattern. In addition, scale density (i.e., the number of scales per unit length), diameter-to-height ratio (i.e., the ratio of the fibre diameter to the spacing of scales), and scale thickness, which vary among different species of animal fibres, will be described below. These differences will help to distinguish various animal fibres morphologically.
2,Cortical layer
Composed of positive cortical cells, partial cortical cells and mesocortical cells, is the main part of the hair fibre. It is also the basic material that determines their physicochemical properties. Positive and biocortical cells distribution degree determines the degree of hair fibre curl. Some animal fibres have pigment particles distributed in the cells of the cortical layer, which makes some animal fibres show different natural colours. For example, cattle wool, down, purple velvet and so on.
3,Medullary layer
It consists of loosely structured and air-filled keratinocytes and is an opaque part in the centre of the hair shaft. The size of the medullary layer varies greatly with different animal fibre species. Observed under a light microscope, the bituminous layer is dark black, and fine hairs generally do not have a medullary layer. It is mainly found in animal fibres of coarse diameter and is distributed in dots, lines, continuous or discontinuous. It is precisely because the cells of the medullary layer are filled with air that they determine the good warmth retention of animal fibres.