Kao has developed an innovative hair dye technology at its European Research Laboratories in Darmstadt. An industry first, the technology uses a new generation of physical dye molecules that dye the hair in a completely new way and thereby deliver multi-dimensional, high-definition shine and long lasting brilliance whilst being gentle to both the hair and scalp. The so-called HD³ dye  technology was developed jointly with Kao Labs in Japan, with experts in photographic dyes from Fujifilm and an eminent authority in dye synthesis from Technische Universität Dresden.  
 
The innovative molecular structure of HD³ dye technology enables unique properties as a dye for hair based on a completely new, non-reactive dye system. Thanks to the small molecular size and the special distribution of the electrical charge, the HD³ dyes penetrate the hair by forming a concentrated ring of color around the outer region of the hair´s core (cortex).  
 
In combination with regular oxidative hair dyes, this creates a multi-layer dyeing effect that interacts with light, leading to vibrant color results with truly multi-dimensional shine. Furthermore, the dyes have high fade resistance, while also being extra gentle to the skin and hair structure. The EU Commission has confirmed that HD³ dye technology has very low allergy potential.