158 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS With the exception of hair that had only been lightly shampooed, all other hair studied always displayed this deterioration of scale edges. However, some hair fibres displayed damage beyond that shown above. As reported by Swift and Brown (1), the next stages of fibre damage that were observed were partial, followed by complete scale removal, see Fig. 3. Again, by rubbing wet hair fibres in a manner that simulated shampooing, it was found that it was possible to remove completely the scale structure from the fibres. Similar rubbing of dry fibres did not produce the same degree of scale damage. Thus it seems probable that shampooing is a contributing factor to complete scale removal. At this stage no assessment has been made of the role of hair brushing and combing in the damage to and removal of scales, although it seems probable (2) that these actions could also produce deterioration in the cuticle. Amongst the hair fibres studied, it was found that complete scale removal only occurred in the last few centimetres. Once complete scale removal had occurred splitting of the fibre end into two, three or more longitudinal sections usually occ•trred, see Fig. 4. Attempts were made to reproduce this type of damage. It was found that brushing a group of fibres that had been subjected to simulated shampooing caused the ends of some of the fibres to split, indicating that shampooing and brushing alone is sufficient to cause the ends of hair fibres to split. At this stage, no attempt has been made to ascertain which of these two actions is most responsible for the production of splitting, or what other procedures can cause splitting. It was noted during the brushing trials that when a fibre had split longi- tudinally, it was common for the individual splits to fibrillate, see Fig. 5. Continued brushing caused these fibrillated regions to break, Fig. 6, thus producing a fibrillated end fibre. The appearance of split ends could vary quite considerably from the simplified breakdown pattern shown in Figs 4, 5 and 6. Some of these variations have been shown by Swift and Brown (1) and DiBianca (6). There is a shortening of fibres associated with the rupture of these fibrillated ends and this shortening appears to keep this type of damage restricted to the last few centimetres of a fibre shaft. These observations have illustrated that shampooing and brushing alone are sufficient to transform the hair from its natural state, Fig. 1, to split ends, Figs. 5 and 6. It seems probable that these grooming treatments of shampooing and brushing are the dominant factors in the physical deterioration of virgin hair. Weathering and exposure to sunlight would appear to be minor effects. If a sample of hair is just stored for hundreds of years, this type of damage does not occur (1), indicating that the deterioration is not an ageing process.

JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Figure 1. Typical appearance of human hair within a few millimetres of root. x 640. •' •"5 '• • • -• •- Figure 2. Typical appearance of human hair over most of the mid-shaft. •e deterioration of scale edge appearance can be caused by shampooing alone. X 64O. (Facing p. 158)