THE PREPARATIONS USED FOR THE CARE OF THE HAIR (POMADES AND HAIR OILS).
The hair, the beautiful ornament of the human body, requires fat for
its care and preservation, for there are but few persons whose scalp is
so vigorous that the hair can derive sufficient nourishment from it to
maintain its gloss and smoothness.
Among the ancient Greeks, Romans, and Germans various ointments were in
use for the care of the hair. In Rome there was even, as we have stated
in an earlier part of the book, a special guild of ointment-makers
or unguentarii. They employed a process for making their ointments
fragrant which resembles that of maceration in present use.
The so-called pomades (from pomum, apple) were prepared by sticking a
fine apple full of spices and placing it for a long time in liquid fat
which absorbed the odor of the spices.
In the present state of chemical science, the basis of every pomade or
hair oil is formed by some fat perfumed with aromatic substances and at
times colored. The fats generally used are lard, beef marrow, tallow,
bears’ grease, olive or almond oil; some of the firmer fats receive
an addition of a certain amount of paraffin, spermaceti, or wax, in
order to give the pomade greater consistence. As in the manufacture of
all the finer articles, it is essential that whatever fat is employed
should be perfectly pure; only fat which is absolutely neutral, _i.e._,
free from acid, can be used, and any sample with but a trace of
rancidity (containing free fatty acids) should be rejected on account
of the penetrating odor peculiar to several of these acids.
Manufacturers who aim at the production of fine goods spare neither
trouble nor expense in order to obtain perfectly pure fats.
Fats are purified for the purposes of the perfumer in the following
manner:
The fat is melted in a bright iron pot or enamelled vessel with three
times the quantity of water containing in solution about one per cent
(of the weight of the fat) of alum and one per cent of table salt. Fat
and water are well stirred with a broad flat ladle or some mechanical
arrangement within the boiler. After the mass has remained at rest for
some time, the curdled solid matters are skimmed from the surface. The
time required for this operation can be much shortened by the use of a
pump which raises the fat and water from the boiler and returns them in
a fine spray.
When fats with some degree of rancidity are to be made suitable for
the purposes of the perfumer, 0.5% of caustic soda lye is added to the
water instead of the alum.
After this treatment is completed, the fat must be washed in order to
free it from the substances with which it was purified. Formerly this
washing was done in a manner resembling the grinding of oil colors.
The fat was placed on a level stone plate and kneaded with a muller
with flat base under a continual stream of water flowing from above,
until the fat was clean. This expensive hand labor is now performed by
machines, the fat being treated with water in vertical mills.
No matter how carefully a fat was purified, it may happen that the
pomades made from it, if kept long in stock, may subsequently become
rancid—a circumstance which may destroy the reputation of a factory.
Fortunately we know two substances which materially counteract the
tendency of fats to become rancid: salicylic acid and benzoin. Either
of these substances is added to many perfumery articles, especially
pomades, in order to prevent rancidity; an admixture of from
one-one-thousandth to five-one-thousandths parts of solid salicylic
acid suffices, according to our experiments, for the purpose; of
benzoin we need about three-fourths of an ounce for every quart of
fat; the resin is only partly soluble in fat, but imparts to it its
vanilla-like odor. For the finest pomades sublimed benzoic acid is
used, in the proportion of about 150 to 240 grains to the quart of fat.