FIG. 24 depicts denaturation temperatures for hair tresses colored in the presence of a mixture of 1 wt % ALA and 1 wt % single amino acid compared to hair tresses colored without an additive mixture and in the presence of 1 wt % ALA alone.

FIG. 25 depicts denaturation temperatures for hair tresses colored in the presence of a mixture of ALA with binary amino acid blend.

FIG. 26 depicts an image showing the color retention performance after 1st and 10th wash for hair tresses color treated with or without a mixture of ALA with binary amino acid blend.

FIG. 27 depicts an image showing the overall color difference (ΔE) after 3, 7 and 10 washes for hair tresses color treated with or without a mixture of ALA with binary amino acid blend.

FIG. 28 depicts denaturation temperatures for hair tresses colored in the presence of a mixture of either 0.5 or 1 wt % ALA, 1 wt % glycine, with one or two more amino acids at either 0.5 or 1 wt % concentrations compared to untreated hair tress and hair tress colored without additives.

FIG. 29 depicts denaturation temperatures collected on hair tresses colored in the presence of a mixture of 0.5 wt % ALA and 1 wt % commercial amino acid blends in liquid form compared to the untreated hair tresses and hair tresses colored without addition of additives.

FIG. 30 depicts an image showing the color retention performance after 1st and 10th wash and overall color difference (ΔE) after 3, 7 and 10 washes for hair tresses colored in the presence of a mixture of ALA, glycine, tyrosine, and palmitic acid.

FIG. 31 depicts an image showing the color retention performance after 1st and 10th wash and overall color difference (ΔE) after 3, 7 and 10 washes for hair tresses colored in the presence of a mixture of ALA, glycine, tyrosine, and palmitic acid.

FIG. 32(a) depicts hair tresses colored in the presence of ternary amino acid blends systems after 1st and 10th wash.

FIG. 32(b) depicts total color loss, ΔE, after 3, 7, and 10 washes.

FIG. 33 depicts denaturation temperatures of hair tresses after coloring treatment with and without various tertiary amino acid blends.

FIG. 34 depicts total color loss after soaking of tresses in water for 30 minutes to mimic 3-7 washing and drying cycles. Tresses were treated with commercial coloring mixtures (Olaplex, Wellaplex, Pro-Force, and ColorKick) with and without N-acetyl L-cysteine pre-treatment step.

FIG. 35(a) depicts total color loss after 3, 7, and 10 washes of tresses treated either with LP developed system or commercial products.

FIG. 35(b) denaturation temperatures of hair tresses after coloring treatment treated with either LP developed system or commercial products.

DETAILED DESCRIPTION
Overview

A permanent hair dye generally consists of oxidative dye precursors (i.e., primary intermediates and couplers) that are oxidized by hydrogen peroxide and form large color molecules inside the hair. Although the oxidative dyes provide long-lasting color, the aggressive chemicals used or formed during the coloring process can cause extensive hair damage. Hair becomes weathered and damaged in response to stresses, including normal wear and tear, harsh cleaning agents (including solvents), washing, drying, brushing, combing, rubbing, styling, bleaching, dyeing, and sun exposure. To reduce the hair damage by coloring and other processes, various methods for coloring hair with additives have been developed. For example, an additive can be incorporated into a coloring mixture or can be used as a separate pre-treatment or post-treatment step before or after dyeing hair. Efforts were also made to deliver more consistent hair color throughout the hair and to provide improved color resistance to regular shampoo and conditioner washes, i.e., improved color retention. Methods to reduce damage and to deliver more consistent hair color with hair dyeing is still an unmet need.

Exemplary Methods for Coloring Hair with Additives

Provided herein are methods for coloring hair with additives. In some embodiments, an additive is in a mixture comprising one or more hair dyes. In some embodiments, an additive is applied before applying a mixture comprising one or more hair dyes. In some embodiments, an additive is applied after applying a mixture comprising one or more hair dyes.

In some embodiments of the methods disclosed herein, the additive composition comprises one or more additives. In some embodiments, the additive composition is a drop-in composition. In some embodiments, the additive is applied simultaneously with a hair dye composition comprising one or more hair dyes. In one aspect, the disclosure provides a method for coloring hair, comprising:

- i) providing a hair sample; and
- ii) applying to the hair sample for a period of time a mixture, comprising one or more hair dyes and an additive in a concentration of about 0.1% by weight to about 15% by weight, thereby producing a color-treated hair sample.