Hair Dye Formulation: Primary and Secondary Intermediates for Black Color

To achieve a black hair color using permanent oxidative dyes, you need a combination of primary intermediates (also known as oxidation bases) and secondary intermediates (also known as couplers). These compounds react with a developer (like hydrogen peroxide) to form the final color molecules within the hair shaft.

The ingredients you mentioned are indeed commonly used in black hair dye:

• Primary Intermediates: PPD (p-Phenylenediamine) and TDS (Toluene-2,5-diamine sulfate) are key primary intermediates for dark shades.
• Secondary Intermediates (Couplers): RL (Resorcinol), MAP (m-Aminophenol), and DPE (2,4-Diaminophenoxyethanol HCl) are couplers that modify and enhance the color produced by the primary intermediates, contributing to the final black shade.

From the available products, we have found:

• N-Phenyl-p-phenylenediamine sulfate (4ADS): This is a derivative of PPD and functions as a primary intermediate suitable for creating dark colors like browns and blacks.
• 1,3-Bis(2,4-Diaminophenoxy) Propane HCl (13BIS): This acts as a coupler (secondary intermediate) and is used to achieve intense and long-lasting shades, including reddish or brown tones that are part of a black formulation.

The specific percentages of each intermediate required will vary depending on the desired intensity of the black color, the starting hair color, and the overall composition of the dye formula.

The Role of Antioxidants

Yes, including an antioxidant in the hair dye formulation (specifically in the dye cream/gel part, before mixing with the developer) is important. Antioxidants, or reducing agents, help protect the dye intermediates from being prematurely oxidized by air during storage. This ensures that the intermediates are available to react correctly with the developer when the product is used, leading to the intended color result and maintaining product stability.

Suitable antioxidants found include:

• Sodium Sulfite (Anhydrous): This is commonly used as an antioxidant in permanent hair dye formulas.
• Sodium Metabisulfite (Germany) and Sodium Metabisulfite (China): These also function as antioxidants to help maintain the quality and stability of ingredients in the formula. They are typically used at a rate of 0.1-0.2%.

Using one of these antioxidants will help preserve the integrity of your dye intermediates before activation.

In summary, a black hair dye formulation requires a blend of primary and secondary intermediates. Products like N-Phenyl-p-phenylenediamine sulfate (4ADS) and 1,3-Bis(2,4-Diaminophenoxy) Propane HCl (13BIS) are relevant ingredients for this purpose. Additionally, incorporating an antioxidant such as Sodium Sulfite or Sodium Metabisulfite is crucial for product stability and optimal color development.