L'Oréal Research and Innovation, Saint Ouen, France.
Consultant, Berkeley, CA, USA.
Skin Res Technol. 2021 Jul;27(4):607-617. doi: 10.1111/srt.12993. Epub 2021 Jan 6.
Hair fibers may be either oriented in a common direction or randomly arranged. Fiber arrangement as well as cosmetic treatment control the sensorial perception. The present study explores the respective influence of these two aspects by predicting the product performance in terms of tactile perception.
Friction forces between hair swatches of different curl patterns using a finger-like probe have been measured to better mimic real-life hair/finger contact. Measurements of fiber alignment, hair diameter (thickness), and compression tests were performed on natural and treated swatches to assess the respective weight of these parameters.
Conditioned hair exhibit an adhesive behavior measured at the start of the frictional movement. Conversely, natural hair is influenced by fiber reorientation. After a few seconds, friction-related signals stabilize. Thus, the averaged friction forces do not only depend on hair thickness, but increase with a decreased alignment of the fibers.
Intrinsic (diameter/curliness) and external (orientation/ friction/compression) characteristics allow to define a model of "macroscopic" roughness linked to the sensorial characterization. As friction of hair swatches depends upon fiber alignment and coating, this combined approach is potentially a very useful in vitro test, as an alternative or complementary method to sensory tests.
毛发纤维可能呈现出定向排列或随机排列。纤维排列和美容处理控制着感官感知。本研究通过预测触觉感知方面的产品性能，探索了这两个方面的各自影响。
使用类似手指的探针测量不同卷曲模式的发束之间的摩擦力，以更好地模拟实际的头发/手指接触。对天然和处理后的发束进行纤维排列、头发直径（厚度）和压缩测试，以评估这些参数的各自权重。
经过调理的头发在摩擦运动开始时表现出粘着行为。相反，天然头发受到纤维重新定向的影响。几秒钟后，与摩擦相关的信号稳定下来。因此，平均摩擦力不仅取决于头发厚度，还随着纤维排列的减少而增加。
内在（直径/卷曲度）和外在（取向/摩擦/压缩）特性允许定义与感官特征相关的“宏观”粗糙度模型。由于发束的摩擦力取决于纤维排列和涂层，因此这种组合方法可能是一种非常有用的体外测试方法，可作为感官测试的替代或补充方法。
