**Identification and Testing Methods for Cashmere and Wool Fibers**

Cashmere is considered a diamond-grade raw material in the garment industry. Its limited production volume and exceptional quality underpin its significant value. Therefore, in the entire apparel material market, cashmere is the only material sold by weight, and despite its high price, it remains in short supply. As the world’s largest cashmere trading market, China currently accounts for 85% of global cashmere production. Among the various types, Cashmere is the most renowned, and many well-known fashion brands have used this material in their garments. However, the current apparel market is plagued by counterfeit cashmere products, which diminish the material's prestige.

**1. Similarities and Differences Between Cashmere and Wool Fibers**

Cashmere and wool fibers are both protein fibers, primarily composed of keratin. Both are formed by the accumulation of many cells, with their cross-sections divided into two or three layers: the outer scale layer, the inner cortex, and the central medulla. Due to their similar composition and structure, they share common characteristics in aspects such as moisture absorption, luster, density, and warmth retention. Cashmere fibers are shorter, have lower strength, and are covered by thin, sparse scales that fit closely together. Cashmere has fewer crimps per unit length than wool, resulting in a lower coefficient of friction and poorer inter-fiber cohesion, but it feels smooth and soft.

Although cashmere has fewer crimps, its crimp depth is greater, allowing an extension rate exceeding 300%, compared to 160% for 64s Merino wool. Consequently, cashmere offers superior warmth retention. Under the same temperature and humidity conditions, cashmere also absorbs moisture more readily than wool.

**2. Identification and Testing Methods for Cashmere and Wool Fibers**

**2.1. Microscopic Projection Method**

As a major cashmere producer, China currently leads many countries in cashmere testing technology and is proficient in applying various testing methods. Among them, the microscopic projection method is the simplest. This technique primarily relies on intelligent electron microscopes. However, its drawbacks include a higher likelihood of errors during scanning and the high cost of electron microscopes. Furthermore, there are few technicians skilled in operating this equipment. Cashmere testing methods are continuously evolving because counterfeit products in the market are improving year by year. Without innovation in testing methods, distinguishing genuine cashmere from imitations becomes difficult. Cashmere testing methods are divided into chemical and physical categories. The microscopic projection method, a chemical method, is relatively common. It offers moderate accuracy and simple operational procedures for the testing instrument. However, it heavily depends on the technician's skill, which limits its widespread application. Under an electron microscope, cashmere scales appear thinner and sparser than wool scales, with better light transmission, more uniform luster, and a relatively even fiber surface. Wool, in contrast, has thicker, opaque scales that often show shadows and a pronounced sense of relief.

**2.2. Computer Projection Method (Computer Image Processing Technology)**

This physical testing method identifies cashmere by converting internal signals from the fiber. It collects dozens of microscopic features to determine fiber properties. However, key indicators for accurately identifying cashmere include scale density, edge thickness, and coverage parameters. Fiber diameter and length can be used to analyze scale data. Slight errors in scale data during testing are not individual indicators but inherent scale characteristics that serve as large data parameters. For stretched wool, which is often used to mimic cashmere, the computer projection method can clearly identify its inferior quality by analyzing subtle features to distinguish wool from cashmere. It can process complex data and present detailed results. *Xi'an Yanshuo Instrument & Equipment Co., Ltd. is an integrated laboratory service provider.*

**2.3. Spectroscopy Technology**

This physical testing method exhibits more distinct physical properties than the computer projection method. When used for cashmere testing, spectroscopic devices induce vibrations in the fiber's internal molecules. By recording the vibration frequencies, they can identify molecular cluster characteristics. A molecular cluster count of five or more is typically classified as cashmere. This technology can also analyze the fiber's structural composition by breaking it down. Cashmere contains a wealth of structural information that reveals its quality. High-quality cashmere presents fine, clear, and well-defined structural details. In contrast, cashmere with a disordered structure may be blended with other materials. Spectroscopy technology requires specialized operation; without professional handling, accurately determining the fiber type is difficult. It offers high precision and is considered the most accurate among current testing methods.

**2.4. PCR Technology**

PCR (Polymerase Chain Reaction) technology has been extensively researched for cashmere and wool identification. This method involves extracting DNA from the fibers, amplifying it via PCR, and then distinguishing between cashmere and wool by comparing their DNA sequences. A challenge with this method is DNA extraction. Hair DNA is primarily concentrated in hair follicle cells. Processed cashmere and wool often lack intact follicles, making DNA extraction difficult. Hair shafts contain even less DNA, so developing reliable DNA extraction methods remains a research focus. Fortunately, relatively mature DNA extraction kits for cashmere exist. For instance, researchers like Tu Mei have successfully used the TaKaRa MiniBEST Universal Genomic DNA Extraction Kit Ver.5.0 to extract cashmere DNA, achieving good DNA amplification curves, primer-probe reactivity, and specificity. This kit helps overcome the difficulty of DNA extraction in PCR technology.

**2.5. Proteomics Method**

Researchers like Stefan Clerens identified 72 complete and 30 partial characteristic wool protein sequences and cataloged 113 wool proteins years ago, enriching the animal fiber protein database and enabling proteomics-based identification of cashmere and wool. Professor Gong has dedicated research to this field. This method uses Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) to analyze cashmere and wool proteins, identifying differences by comparing their peptide sequences. One difference is that cashmere-derived peptides show a characteristic peak at a mass-to-charge ratio (m/z) of 2691.3. Database searches reveal its amino acid sequence: YSCQLNQVQSIVNVFSQLAFR. Wool-derived peptides show a characteristic peak at m/z 2664.5, with the amino acid sequence: YSCQLSQVQSIVNVFSQLAFR. The difference is a serine residue in wool replaced by an asparagine residue in cashmere, enabling differentiation. However, parameters for cashmere and wool fibers can overlap, and relying on a single property for identification can lead to significant error rates. Therefore, identifying a suitable set of evaluation indicators and establishing a comprehensive assessment system to minimize error rates remains a key goal for fiber testing professionals.

羊绒、羊毛纤维检测鉴别方法，羊绒于服装材质中属钻石级别原材料，其极少产量和优异品质，奠定其不菲价值。因此，在整个服装材料市场中，仅有羊绒一种材料是依据克数贩卖，其昂贵售价依旧供不应求。我国作为全球最大的羊绒贸易市场，现阶段羊绒产量已占到全世界总产量的85%。羊绒的种类丰富，其中Cashmere羊绒最为驰名，许多知名服装品牌都曾运用Cashmere羊绒材质制作成衣，但是，当下服装市场却存在假冒羊绒制品的商品，令羊绒降低原有档次。
 

1 羊绒与羊毛纤维的异同性

羊绒和羊毛纤维同属蛋白质纤维，基本组成均为角阮蛋白，都是由许多细胞聚积而成的，其截面分布划分为2或3个层次，即外表面的鳞片层、内部的皮质层和中心的髓质层。由于它们的组成和组织结构相近，故在吸湿、光泽、密度、保暖性等许多特性方面有共同点。羊绒纤维长度短、强力低，表面覆盖的鳞片薄而稀，彼此紧贴，纤维卷曲数比羊毛少，所以摩擦系数比羊毛小，纤维间抱合力相对较差，但手感滑糯。

虽然羊绒纤维卷曲数少，但卷曲深度大，伸直度可达300%以上，而64支美利奴羊毛仅为16000，因此羊绒纤维保暖性优于羊毛。在同样温湿度条件下，羊绒比羊毛更容易吸湿。

2 羊绒、羊毛纤维的检测鉴别方法1 R

2.1 显微镜投影检测法。作为羊绒产量大国，现阶段我国羊绒检测技术已领先于世界多数国家，针对羊绒检测技术的应用也较为熟练，其中显微镜投影检测法是所有检测方式中最为简单的一种检测技术，这种技术主要依靠智能型电子显微镜进行检测，其弊端在于扫描过程中较易出现错误，且电子显微镜的成本极高，当下可进行电子显微镜专业操作的技术人员也较少。羊绒检测方法一直在改变，源于市场羊绒仿制品的品质逐年增高，如果不进行测试方法的革新，便会导致羊绒仿制品与正品的混搅。羊绒的检测方法分为化学类检测和物理类检测，其中化学类的显微镜投影检测法是比较常见的一种羊绒检测方式，这种方法的精度中肯，且检测仪器的操作规范简便，但其过于考验检测人员的检测技术，因此其应用并非特别广泛，且显微镜投影检测法具备一定的局限性。在电子显微镜下羊绒鳞片相较羊毛更为稀薄，且透光性更好，光泽均匀，纤维凹凸层也较为平均。而羊毛则是厚重鳞片，不仅无光泽，且其表层透出明显暗痕，阴影感亦较重。

2.2 计算机投影检测法。计算机投影检测法别称为计算机图像处理技术，该技术通过对羊绒内部信号的转换实现其类别信息的检测，且计算机投影检测法被归类为物理类检测技术。该技术通过采集羊绒的微观特征对羊绒属性进行鉴定，其针对羊绒特征的采集包含数十种类别，但可精准判断羊绒材质的仅有鳞片密度、边缘厚度和覆盖参数。其中纤维径长可用来分析鳞片测试数据，鳞片数据在测试阶段中会存在些微误差，这些误差并非羊绒单个指标，而是其鳞片原有特征，这些特征作为大数据参数而存在。其中，经过拉伸的羊毛，其目的是冒充羊绒，在实际检测中，针对这类问题，投影检测法可以清晰判断其劣质品质，该检测法可根据些微特征来判断羊毛或羊绒的属性，其检测可辨别较为困难的检测数据，并将该数据详细列出。西安研硕仪器设备有限公司实验室一体化集成服务商。

2.3 光谱检测技术。该技术归类为羊绒的物理型检测技术，且具备相较计算机投影检测法更为明显的物理性质。运用光谱检测技术进行羊绒检测时，光谱装置令羊绒内部分子产生振动，并根据对震动频率的记录，判断其分子团特征，分子团数量大于或等于5便被判别为羊绒。其装置还可通过分解羊绒来判断其结构的构成方式，羊绒结构之中包含大量物质类信息，从这些信息之中可判断羊绒材质的优劣，优秀的羊绒材质信息较为精细，且结构一目了然，十分明确。而结构混乱的羊绒其材质本身很可能掺杂其它类别的材质。在检测方式上，光谱检测技术的操作模式更偏向专业化，如非专业人员进行操作便很难判断材质的真正类别。光谱检测技术在准确性上较高，其检测的信息在所有检测方法中最为精确。

2.4 PCR技术。PCR技术应用在羊绒羊毛的检测上已经获得很深入的研究，该方法是提取羊绒羊毛的DNA，然后用PCR技术进行扩增，通过对比二者DNA的小同来进行羊绒羊毛的鉴别。该方法的缺点是DNA提取困难，因为毛发中的DNA主要集中在毛囊细胞中，经过加工处理的羊绒羊毛很少带有完整的毛囊，所以从毛囊细胞中提取DNA十分不易。而DNA含量比毛囊中更少，所以DNA的提取方法仍旧是目前研究的热点。所幸已经有比较成熟的山羊绒DNA提取试剂盒，如土玫等人利用TaKaRa MiniHEST Lniversal Genomic DNA Extraction Kit Ver.5.0试剂盒提取山羊绒DNA，能够得到很好的DNA扩增曲线，引物探针反应性能和特异性能均较好。应用该试剂盒能克服目前PCR技术中DNA提取小易这一难点。
 

2.5 蛋白质组学法。Stefan Clerens等人早在五年前就已经测定出72个完整的和30个部分羊毛特征蛋自质序列，并且确定了113个羊毛蛋自质，丰富了动物纤维蛋自质数据库，为蛋自质组学法进行羊绒羊毛的鉴别提供了可能性。龚副教授一自致力于蛋自质组学鉴别羊绒羊毛的研究。该方法是利用基质辅助激光解吸电离、飞行时间质谱（Matrix-Assisted laser Desorption Time of Flight）进行羊绒羊毛蛋自质的测定，通过比较二者蛋自序列的差异进行鉴别。二者差别之一是：羊绒提取多肤在质荷比为2691.3处有特征峰值，经质谱网络数据库检索得出其氨基酸排列顺序为：YSCQLNQVQSIVNVFSQLAFR（每个大写字母代表一种氨基酸，如Y代表酪氨酸）。所测羊毛提取多肤在质荷比2664.5处有特征峰值，经质谱网络数据库检索得出其氨基酸序列为：YSCQLSQVQSIVNVFSQLAFRo即在羊毛中是丝氨酸的位置，在羊绒中变成了冬酞胺，据此可以进行羊绒和羊毛的鉴别。羊绒、羊毛纤维的各项参数存在一定的交叉，单独以某项性质作为判别指标难免会产生较大的误判率。因此，寻找一套适合的评判指标，建立完善的评价系统，较大程度地降低误判率，仍是纤维检测工作者的努力方向。