| 摘要 |
The present invention concerns improved processes for dyeing keratinous fibers especially hair on the human scalp using a two-step oxidation process for the oxidation of the melanin precursors 5,6-dihydroxyindoline (DHIN), 5,6-dihydroxyindole (DHI), and derivatives thereof such as 5,6-dihydroxyindole-2-carboxylic acid (DHICA). |
