Hair Lacquers
Use of Dewaxed Bleached Shellac in Hair Lacquers
Use of Dewaxed Bleached Shellac in Hair Lacquers
Shellac’s world-wide use in hair sprays is growing and the hair lacquer industry itself is a dynamic one in which formulations are constantly changing. Shellac combines all the chemical and physical properties required by the cosmetics chemist in formulating hair-grooming products.
The ability of shellac to hold the hair is an obvious basis requirement and its non-hydroscopic nature ensures that the hair keeps well-groomed even on humidity or when exposed to rain. Its solubility in alcohol, the usual cosmetic solvent, makes for easy formulation, and its solubility in mild alkalis makes for easy removal by shampoos.
Shellac has a wide range of compatibility with other resins, plasticizers and softeners used in hair lacquers. This has enabled the cosmetics chemist to modify his formulation to include polyvinyl pyrrolidone, polyvinyl acetate etc, to give products with special properties. The basic alcoholic shellac solution tolerates the addition of special solvents which are necessary to promote compatibility with the propellants normally used in aerosol sprays.
In addition to other resins used in combination with shellac a number of plasticizers are often employed to soften the film, prevent flaking and aid in removability.
There are two basic types of hair spray formulae, those that are mechanically dispensed in the salon and those designed for pressure packaging as aerosols. The non-aerosol type of hair sprays are straight solutions of decolourised shellac or bleached lac in alcohol or dilute solutions of mild alkalis, with plasticizers, perfumes and preservative as required. A starting formula for an alcohol/water type of product would be:
| Parts by weight | |
| Dewaxed Bleached Shellac | 60 |
| Borax | 15 |
| Alcohol | 160 |
| Water | 250 |
To a solution of Dewaxed Bleached Shellac in alcohol, water in which borax has been previously dissolved is slowly added.
Water and water/alcohol systems are in demand because of their economy, non inflammability and easy to use.
Tests supported by actual use for many years, have shown that Dewaxed Bleached Shellac, is the best grade of shellac for aerosol sprays; it is stable and does not contain any chlorine, which causes such troubles as perfume breakdown and corrosion. Even more important is the fact that it contains 2.5% water. Excess of water in aerosol formulae, according to recent publications, causes propellant instability. The following is a typical American formula for aerosol hair lacquer:
| Parts by Weight | |
| Dewaxed Bleached Shellac in alcohol (35% solids) | 4.50 |
| Plasticizers or pvp/va e-735 | 0.20 |
| Lanolin or Derivative | 0.10 |
| Perfume | 0.10 |
| Methylene Chloride | 5.00 |
| Anhydrous alcohol s.d. no. | 25.10 |
| Propellant (80/20 f11/f12) To (60/40/f11/f12) | 65.00 |