Hair color changes caused by dyeing and thermal treatments

The effect of color on instrumentally evaluated luster of hair dyed to different colors and depths of shades is studied. For natural hair colors, such as blond, brown and black, the increase in luster with increasing color is associated with a decrease in diffusely scattered light as a result of light absorption by melanin granules. On dyed hair the interpretation of data from a goniophotometer (GP) is more complicated. Using the colors covering the extremes and middle of the visible spectrum, our results demonstrate how dye composition (single or multicomponent), concentration and penetration depth into the fiber affect the absorptive and scattering processes within the hair fiber to impact luster. Finally, we make an attempt to study the effect of hair color on subjective evaluation of luster. An equation for perceived luster, taking into account the spectral sensitivity of the human eye is derived. Theoretical considerations show that the human eye perceives the luster of hair of different colors differently.     

危机不应该被轻易浪费——尼日利亚、埃及、土耳其经贸考察有感

浙商总是先人一步,当大家仍在关注欧、美、日等发达地区市场的时候,浙江省政府带领浙商又对尼日利亚等非洲新兴市场进行了经贸考察,拓展视野。本刊发表赵林中同志的考察感想,与读者分享。