Hair Colorants and Highlighting

 Hair coloring is a technique used by both men and women for:

 Covering gray can be considered a universal key motivator.

 Enhancing the existing color

 Wanting a different color from the natural hair color.

 Hair dyes are products that alter the color appearance of hair temporarily or permanently, by removing some of the existing color and/or adding new color.

 Home and salon hair dyes are based on the same technologies, while there are key differences in colors and application variety.

Types of hair dyes

 They are classified according to the permanency of the induced color change into:

1. Gradual hair dyes: color is produced in several applications.

2. Temporary hair dyes: wash out with one wash.

3. Semi-permanent hair dyes: wash out with 6-8 washes.

4. Oxidative dyes: they are two types:

• Demi-permanent hair dyes: wash out with up to 28 washes with new roots grow out.

• Permanent hair dyes: permanent (wash out withnup to 50 washes) with new roots grow out.

1. Gradual Hair Colorants

 They require repeated application to result in gradual darkening of the hair shaft from gray to yellow-brown to black over a period of weeks.

Chemistry

 They are known as metallic dyes because they work by depositing metal salts (ex. Lead, bismuth, etc) on the hair shaft in the form of dark colored oxides, suboxides, and sulfides.

Advantages

 Low cost.

 Ability to perform the dyeing procedures at home without the need of a professional operator.

Disadvantages

 For the following disadvantages, gradual hair dyes are not suitable for females, and are most popular among men.

 Poor color quality, stiff, brittle, and dull hair may result

 Lightening is not possible and there is no control over the final color of the hair.

 Deposited metal can cause breakdown of the hydrogen peroxide in bleaching or permanent waving products, resulting in rupture of the hair shaft.

2. Temporary Hair Colorants

 Also known as color rinses.

 They are removed in one shampooing.

 The binding forces between hair substrate and dyes are low so color is easily washed out after the first shampoo.

 There are several formulations of temporary dyes: liquid, mousse, and gel.

Advantages

 Suitable for men and women of all hair types.

 No damage is imparted to the hair shaft.

 Available with party colors for teenagers.

 Suitable for persons who are allergic to paraphenylenediamine ( ingredient in permanent dyes).

 Suitable for people who are waiting for fading of the undesirable color and new growth in case of that repeated dyeing procedures undertaken in a short period of time may result in undesired color or irreversibly damaged hair.

Disadvantages

 The dye can be easily rubbed off the hair shaft and can run onto clothing if the hair gets wet from rain or perspiration.

3. Semi-permanent hair colorants

• They are retained in the hair shaft by weak forces, so last for 6–8 shampooings.

• Semipermanent dyes produce tone-on-tone or ‘On Shade’ coloring rather than producing strong color changes, so their role is actually in toning rather than dyeing hair.

• It is not possible to lighten hair with semipermanent dyes, since they do not contain hydrogen peroxide, nor is it possible to darken hair more than three shades beyond the natural hair color.

• Best suited for patients with less than 30% gray hair who want to restore their natural color.

• Types of Semi-permanent dyes are: textile dyes, vegetable dyes, and synthetic hair stains.

Natural Henna

• It is one of the Vegetable dyes and botanically known as Lawsonia alba.

• Pure Henna is a semipermanent dye because minimal cuticle penetration occurs allowing removal of the dye.

Application

• Powder is mixed with hot water to make a paste and placed on the head for the instructed time mentioned on the product packaging.

Disadvantages

• Complicated preparation and application.

• Leave the hair stiff and brittle after repeated applications.

• Only used for darkening without control on the resulted color.

• The contrary effect of showing white hair off.

• Original hair color can’t be lightened.

• Prevent further chemical hair treatments like relaxing or permanent hair coloring.

Safety

• Henna has not been reported to cause allergic contact dermatitis when used as a hair dye.

4. Oxidative hair colorants

 They are called oxidative because oxidizing agents are used in the formation of color molecules.

 They are the most frequently used and commercially most relevant hair dyes due to:

 Tremendous variety of colors

 Lastingness of the produced color

 Ability to both darken and lighten the color of hair

 Their long lasting effect is because that the dye molecule penetrates the hair shaft into the cortex and forms large color molecules that cannot be removed by few numbers of shampooing.

 Redyeing is necessary every 4–6 weeks due to the growth of new hair at the root level.

Types of oxidative dyes

 There are two types of oxidative dyes:

 Demi-permanent hair dyes: wash out with up to 28 washes with new roots grow out.

 Permanent hair dyes: permanent (up to 50 washes) with new roots grow out.

 Permanent dyes differ from demi-permanent dyes in the type and level of alkalizing agent and the concentration of peroxide, which result in different color results, lastingness of the produces colors, ability to cover gray hair and the ability to lightening the hair color.

Chemistry

• The customer is instructed to mix the contents of a group of bottles (or tubes) together and shake vigorously.

• This mixing brings four key ingredients together: Hydrogen peroxide, dye precursor, coupler and the alkalizing agent.

• The alkalizing agent act as a catalyst for Hydrogen peroxide.

• The catalyzed hydrogen peroxide oxidize the dye precursor to produce an active intermediate. Here the color starts to appear but it is not the final color of the hair colorant.

• The active intermediate then combine with the coupler to give the final color of the color molecule that will be inserted within the cortex of the hair shaft to give it its new color.

Role of Hydrogen peroxide

• Oxidizing the dye precursor to produce the color molecule that will be inserted in the cortex.

• Oxidizing melanin granules and previously found color molecules within the cortex to lighten the color of the cortex which give the new formed color more and better appearance.

• When the concentration of the hydrogen peroxide increase, the ability to lighten the color of hair increase due to the increase in the oxidation of melanin within the cortex.

Role of Alkalizing agent

• To catalyze Hydrogen peroxide to start its oxidative activity.

• Raise the ph of cuticle to swell and increase its porosity to allow the entrance of the color molecule and the oxidizing agent into the cortex.

• Raising the strength of the alkalizing agent gives stronger oxidative effect of hydrogen peroxide which result in more lightening of the melanin to give lighter colors.

• Ammonia is the most potent alkalizing agent used hair coloring.

• Using an alkalizing agent less potent than ammonia ( as in demi-permanent dyes like L’oreal Casting) lead to:

 The duration of color last for a shorter period than the permanent.

 The ability of the colorant to lighten the color hair is less than in permanent hair dyes.

Method of use of home kit

1. User should read the instructions of the kit and stick strictly to the time of each step mentioned in the instructions.

2. The two bottles are combined immediately prior to use and must be shaken vigorously to thoroughly mix the ingredients.

3. The dye must be applied immediately to dry unwashed hair since sebum minimizes scalp irritation and cannot be saved for later use.

4. The dye is left in contact with the hair for 25–40 minutes, depending on the color selected and whether the hair has been previously chemically treated.

5. If the hair has been dyed previously, the dye is only applied to the new growth at the scalp initially and then combed through the ends of the hair for the last 10 minutes. This is due to the fact that previously dyed hair has a damaged cuticle and the dye will penetrate more rapidly. If the hair dye is left on new growth and previously dyed hair for the same length of time, the previously dyed hair will be a darker shade.

6. Once the dye has been left on the hair for the desired amount of time, it is thoroughly rinsed with water until the water runs clean. The hair dye must be removed from the skin and hair, since it will dye any protein.

7. Following rinsing, the hair is shampooed with a special conditioner. The dye induces cuticle swelling, which must be reversed to prevent excessive hair damage.

Highlighting

 This technique involves the application of permanent hair dye to selected locks of hair to create color variation in the hair.

 The variation creates a more cosmetically pleasing appearance.