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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. |
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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.
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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 |
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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 |
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