I. Soc. Cosmet. Chem., 27, 379-398 (September 1976) Combability Measurements on Human Hair MARIO L. GARCIA, Ph.D. and JOSE DIAZ, B.S.* Presented May 29, 1975, SCC Seminar, St. Louis, Missouri Synopsis: An instrumental method for MEASURING the effect of cosmetic products or any other treatment of the COMBABILITY of HUMAN HAIR has been developed. The required instrumentation, experimental procedure, and interpretation of the data are presented in detail. The method involves the continuous recording of the forces, which oppose the motion of a comb through a swatch of hair. The data thus produced consists of graphs showing the forces opposing (or generated by) combing as a function of the position of the comb along the length of the swatch. Examples of applications are presented. INTRODUCTION Combability can be defined as the subjective perception of the relative case or difficulty with which human hair can be combed. It depends on the magni- tude and on the fluctuations of the forces that oppose combing. Combability is an important attribute, which is always considered when judging the "condition" of human hair. Improved combability is perceived as the hair being in better condition. Another concept closely associated with combability is that of manageability. Still another factor related to combability is that of the mechanical damage, which is done to hair with the combing process, which is accelerated if the hair is hard to comb or to untangle. It fol- lows that combability, due to its close connection with other desirable hair qualities, is a very important factor in judging the performance of many hair care products. The method described in this paper was developed in our laboratories for the purpose of quantitatively evaluating combability. It has been extensively tested with a wide variety of hair products and treatments and is now used as a standard test during product development and for claim substantiation in finished products. A number of instrumental methods for evaluating combabil- ity have been reported in the literature (1-3). Some of the similarities and differences between those methods and ours will be discussed later. It is our opinion that our method has advantages in its simplicity and in the type of information that can be obtained by using it. *Clairol Inc. Research Labs., 2 Blachley Road, Stamford, Conn. 06902. 379

380 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS In what follows, the method is first described in full detail so that it can easily be used by any interested laboratory. This description is followed by a selected number of experimental results, interpretation of the data, and a general discussion of the method. M•.TaOD Experimentally, the method consists of suspending a hair swatch from a force-measuring device, inserting a comb close to the root end of the swatch, setting the comb in a straight combing motion through the swatch at a con- stant speed, and continuously recording the forces that resist its motion during this transit from the point of insertion till it clears the tip end of the swatch. The data resulting from this operation consist of a graph showing the load (in grams) opposing (or generated by) combing as a function of the position of the comb along the length of the swatch. We call this graph a 'Combing Curve.' Combing curves can be recorded using dry or wet hair. Typical examples of these curves can be seen in Fig. 1 (dry) and Fig. 2 (wet). Dry combing curves are recorded using swatches, which have been previously hand combed. In spite of the precombing, they show gradually increasing comb- ing forces which reach maximum values at or near the tip end of the swatch. Wet combing curves are recorded using swatches which have been purpose- ly tangled by immersing them in water. The resulting curve shows a high in- cidence of tangles all through the length of the swatch. In some cases, the combing forces are higher close to the tip end of the swatch. In our method, combabqity is measured by means of two parameters, which can be directly obtained from the combing curves. The first parameter is 'peak combing load' (PCL). This is the highest load (in grams) that is re- corded during the combing of the swatch. Points P in Figs. 1 and 2 are ex- amples of PCLs. If desired, PCL can be converted to peak combing forces (PCF) (in dynes) by multiplying them by the acceleration of gravity (•980. cm/sec2). The second parameter is the average combing load (ACL). This is the average load during one combing of the swatch. It is expressed in grams ß cm units) by the distance in centimeters traveled by the comb through the swatch. Both of these parameters give us a quantitative measure of how difficult (or easy) it is to comb a swatch of hair. Our method is based on measuring the changes that occur in such parameters when the hair is treated with a product. Decreases in PCL and/or ACL, which indicate improvements in combability (and vice versa) correlate with what is perceived when the hair is combed by hand. As could be expected, the absolute values of the PCLs and ACLs depend on a large number of facto.rs such as speed of combing, handling of the hair, dimensions of the hair swatch, curliness of the hair, comb dimensions, comb material, etc., which cannot be totally controlled. It is for these reasons