* Mordant: A mordant helps to bind the dye to the hair fibers. It creates a chemical link between the dye molecules and the proteins in the hair (keratin), allowing the color to adhere more effectively and last longer. It also helps the dye to penetrate the hair shaft.
* Colorant: Sodium picramate itself contributes to the color, typically creating a yellow or orange-red hue. It is used primarily in temporary or semi-permanent hair dyes to add or modify color tones.
Here's a more detailed explanation:
1. Binding: Sodium picramate interacts with the hair's keratin proteins, creating a bridge that allows the dye to bond to the hair.
2. Color Modification: It's used to enhance or modify the shade achieved by other dye components.
3. Temporary or Semi-Permanent Dyes: It is not very effective in permanent dyes. It's more commonly found in semi-permanent or temporary hair color formulations due to its relatively weak binding and gradual fading properties.
Safety concerns
Sodium picramate has some potential drawbacks. It can be:
* Allergenic: Some people may experience skin irritation or allergic reactions from it.
* Skin sensitizer: Can cause sensitivity to the sun.
* Explosive risk: Picrates are explosively dangerous, and must be handled with care to avoid detonation.
Given the potential risks and the availability of alternative mordants and colorants, sodium picramate is not as widely used in modern hair dyes as it once was. However, it can still be found in some formulations, especially in certain traditional or specialized products.