Dissolution Issue with PPD and Resorcinol in Hair Dye Formula

Question

Regarding the solubility of PPD and Resorcinol in a hair dye formula. The amounts used are in %W/W.

Colorant Part:
GuarCat 10%
Poly-Conditioner Eco 2%
ColorFix 5%
Butylene Glycol 5%
ascorbic acid 0.5%
Phenoxyethanol 1%
PPD 0.27%
RL 0.275%
Add water to make up to 100%

Developer Part:
Disodium EDTA 0.1%
GuarCat 2.5%
Ceteareth-20 2.5%
Silicone Hi-Cond 1%
H2O2 10 Volume 50%
Sodium Stannate 0.03%
Add water to make up to 100%

The ingredients are mixed all together (weighing everything and then adding water) and the pH is adjusted to 9 with Triethanolamine. However, PPD and RL still do not dissolve, and testing on hair samples shows no change other than the original hair color becoming lighter.

Are there any recommended techniques, such as dissolving certain parts separately first, a specific order of adding ingredients, or using temperature to aid dissolution? Thank you.

MySkinRecipes Expert · Accepted Answer

Improving PPD and Resorcinol Dissolution in Hair Dye

It sounds like you are experiencing issues with the solubility of PPD and Resorcinol in your hair dye colorant formulation, which is affecting your dyeing results. PPD (p-Phenylenediamine) can be less soluble in water at room temperature compared to Resorcinol. Proper dissolution of these dye intermediates is crucial for the oxidative dyeing process to work effectively with the developer.

Here are some recommended techniques to improve the dissolution of PPD and Resorcinol:

Recommended Dissolution Technique

Instead of adding all ingredients at once, try dissolving the PPD and Resorcinol separately in the solvent components before combining them with the rest of the formulation:

Prepare Solvent Base: Measure out the total amounts of water and Butylene Glycol required for your colorant formula.
Dissolve PPD: In a separate container, add the PPD to the Butylene Glycol and a portion of the water. Gently heat this mixture to around 40-50°C while stirring. Heating helps significantly improve the solubility of PPD. Continue stirring until the PPD is completely dissolved.
Dissolve Resorcinol: In another container, dissolve the Resorcinol in the remaining portion of the water. Resorcinol is highly soluble in water and should dissolve easily at room temperature.
Combine Dye Solutions: Once both the PPD and Resorcinol are fully dissolved, combine the two solutions. Stir thoroughly to ensure a homogeneous mixture.
Add Other Ingredients: Add the remaining ingredients from your colorant formula (GuarCat, Poly-Conditioner Eco, ColorFix, Ascorbic Acid, Phenoxyethanol) to the dissolved dye mixture. Mix until all components are uniformly dispersed or dissolved.
Adjust pH: Finally, adjust the pH of the colorant mixture to 9 using Triethanolamine, as you have been doing.

Using Temperature: Applying gentle heat (40-50°C) specifically during the dissolution of PPD is a key step to improve solubility. Allow the mixture to cool before adding any heat-sensitive ingredients, although the components in your formula are generally stable at these temperatures for a short duration.

Order of Addition: Dissolving the primary and secondary dye intermediates (PPD and Resorcinol) first in the appropriate solvents ensures they are fully available for the chemical reaction later. Adding other ingredients like thickeners and conditioners after the dyes are dissolved can prevent them from interfering with the dissolution process.

Impact on Dyeing Results: Undissolved dye precursors cannot participate in the oxidation reaction with Hydrogen Peroxide. This directly leads to poor color development and uneven dyeing, which explains why you are only seeing the original hair color lighten. Ensuring complete dissolution of PPD and Resorcinol is the fundamental step for achieving effective oxidative hair dyeing.

Always remember to keep the colorant and developer parts separate until immediately before application, as mixing initiates the dyeing reaction.