DHA as a hair colourant

Abstract

There is described a method for colouring hair, said method comprising treating hair with a composition comprising dihydroxyacetone (DHA), in free form or in salt form; optionally drying the hair; and heating the treated hair, including the applied DHA composition, to a temperature of from about 100° C. to about 250° C.

Claims

1. A method for colouring hair, said method comprising treating hair with a composition comprising dihydroxyacetone (DHA), in free form or in salt form; optionally drying the hair; and heating the treated hair, including the applied DHA composition, to a temperature of from about 100° C. to about 250° C.; provided that said composition does not include additional colorants.

2. The method according to claim 1 which comprises applying the DHA composition to select portions of the hair.

3. The method according to claim 1 which comprises applying the DHA composition to all of the hair of the head.

4. The method according to claim 1 wherein the DHA composition is applied to dry hair, wet hair or damp hair.

5. The method according to claim 1 wherein the hair is shampooed or rinsed prior to the application of the DHA composition.

6. The method according to claim 1 wherein heat is applied to the DHA treated hair within about 5 minutes after application of the DHA.

7. The method according to claim 1 wherein the treated hair is heated for a time period from about 1 minute to about 60 minutes.

8. The method according to claim 1 wherein a hot iron is used to apply heat to the treated hair.

9. The method according to claim 8 wherein the hot iron is selected from the group consisting of a curling iron, a straightening iron or a hot comb.

10. The method according to claim 1 wherein after the heating is complete, the hair is rinsed or shampooed as desired.

11. The method according to claim 1 wherein the amount of DHA, in free form or in salt form, present in the composition is from about 1 to about 20% w/w.

12. The method according to claim 1 wherein the DHA composition is oil based or is an aqueous solution.

13. The method according to claim 1 wherein the DHA composition includes one or more water-soluble solvents.

14. The method according to claim 13 wherein the one or more water-soluble solvents is selected from the group consisting of glycerin, mono-alcohols, polyols (polyhydric alcohols), glycols, and mixtures thereof.

15. The method use according to claim 1 wherein the DHA composition includes one or more thickening agents.

16. A kit for colouring hair, said kit comprising: a composition comprising dihydroxyacetone (DHA), in free form or in salt form; provided that said composition does not include additional colorants; optionally an applicator for the DHA composition; and means for heating the treated hair.

17. A kit according to claim 16 wherein the means for heating the treated hair is capable of heating the treated hair to a temperature of from about 100° C. to about 250° C.

Description

EXAMPLE 1

(1) 10% w/v solution of DHA was applied to skin and different hair types (white and 50% grey) for 16 hours at room temperature/body temperature.

(2) Result

(3) Colour change on skin was observed within 2 hours, no change in hair colour after 16 hours.

EXAMPLE 2

(4) DHA (6.0%) was formulated into a gel and cream, applied to hair samples (bleached, white, 50% & 90% grey) and kept at room temperature and 40° C. for 24 hours.

(5) Result

(6) No colour change with either gel or cream formulation at room temperature. Noticeable colour change in samples kept at 40° C.

EXAMPLE 3

(7) DHA (6.25%) solution was applied repeatedly to hair samples (bleached, blonde, 90% grey) for 5 minutes every 24 hours. After application, the hair fibres were treated in different ways (A-D) A Blow dry B Blow dry+thermal straightening (200° C.) C Shampoo/conditioner+blow dry D Shampoo/conditioner+blow dry+thermal straightening (200° C.).

(8) Result

(9) A Samples noticeable change colour after 5 applications.

(10) B Samples change colour immediately.

(11) C Samples noticeable change colour after 5 applications.

(12) D Samples change colour immediately.

EXAMPLE 4

(13) DHA solution (1.0-6.0%) was applied to hair samples (bleached, white, 90% grey) for 5 minutes, then blow dried and thermally straightened (200° C.).

(14) Result

(15) Immediate colour change in all samples, darkening with increasing % inclusion.

EXAMPLE 5

(16) Wash-fastness of hair treated once with DHA solution (2.0, 4.0, 6.0% w/w) for 5 minutes, blow dried, and thermally straightened (200° C.).

(17) Result

(18) Shows good, consistent wash-fastness up to 8 washes—some loss in colour.

EXAMPLE 6

(19) Indigo (25%) and DHA (6.25%) were mixed into a paste, left to develop for 30 minutes, applied to white hair for 1/⅔ hours, rinsed, blow dried, and straightened (240° C.).

(20) Result

(21) New colour different to indigo used on its own.

EXAMPLE 7

(22) Indigo (10, 15, 25%) was mixed into a paste, left to develop for 1 hour, applied to hair (bleached, white, 90% grey) for 1 hour, rinsed, blow dried, and straightened (240° C.). Colour was left to develop or 24 hours, after which a solution of DHA (6.25%) was applied for 5 minutes, blow dried, and straightened (240° C.).

(23) Result

(24) Get a purple/brown colouration after application of heat, which darkens slightly after 24 hours from application of DHA solution.

EXAMPLE 8

(25) Henna (25%) and DHA (6.25%) were mixed into a paste, left to develop for 1 hour, applied to white hair for 1/⅔ hours, rinsed, blow dried, and straightened (240° C.).

(26) Result

(27) New colour different to henna used on its own.

EXAMPLE 9

(28) Henna (5%), indigo (10%), and DHA (6.25%) were mixed into a paste, left to develop for 1 hour, applied to white hair for 1/⅔ hours, rinsed, blow dried, and straightened (240° C.).

(29) Result New colour different to henna/indigo used on their own in that ratio.

EXAMPLE 10

(30) Nisarg blends; Sienna; Copper; Caramel; and brown, were mixed with water (different ratios) into a paste, left to develop for 1 hour, applied to hair (bleached, white, 90% grey) for 1 hour, rinsed, and blow dried. Colour was left to develop or 24 hours, after which a solution of DHA (6.25%) was applied for 5 minutes, blow dried, and straightened (240° C.).

(31) Result

(32) After application of the DHA solution, all the hair samples darkened.

EXAMPLE 11

(33) DHA solution (6.00%) was applied to hair samples (bleached, white, 90% grey) for 5 minutes, then blow dried and thermally straightened at varying temperatures—in order to gauge the minimum temperature needed to induce an immediate colour change.

(34) Result

(35) Varying degrees of colouration with different applied temperatures. Colour change begins at 120° C., and the colour darkens with increasing temperature.

EXAMPLE 12

(36) Nisarg blends; Sienna; Copper; Caramel; and brown, were mixed with water and conditioner (different ratios) into a paste, left to develop for 1 hour, applied to hair (white, bleached, 90% grey) for 1 hour, rinsed, and then blow dried.

(37) The blend dyed hair samples were treated with DHA solution (4%) for 5 min, dried and then straightened (240° C.).

(38) Wash Fastness was carried out on those samples in order to compare water and conditioning liquid effects with the addition of DHA.

(39) Result

(40) Regardless of the whether the natural dye blends were mixed with water or conditioning liquid, the addition of DHA improves wash-fastness across all the blend colours (Lower ΔE*, ΔL*, Δa*, and Δb*).

EXAMPLE 13

(41) DHA solution (1.00-6.25%) was applied to oxidatively dyed hair for 10 seconds, and then blow dried and thermally straightened (240° C.).

(42) Wash fastness was carried out on those samples in order to compare change in colour with washing between an oxidatively dyed hair sample and an oxidatively dyed hair sample treated with DHA.

(43) Result

(44) Regardless of the concentration of DHA applied, wash-fastness is improved; showing increasing improvement with increasing concentration of DHA.