Metallic
salt hair dyes
Metallic
salt dyes have been with us for a long time. The old paint and brush
on hair dyes for gray hair used in the 1800s were metallic salt
dyes. The basic ingredients have not actually changed that much.
Metallic salt dyes of old almost always contained a lead compound,
but modern dyes contain a variety of other metals depending on the
shade of color. When the metallic salt compound is applied to the
hair the metal salts undergo a chemical reaction to deposit a colored
film on the hair fiber surface. In general these dyes do not penetrate
inside the hair fiber, they just coat the surface.
These surface dyes can bring disadvantages. Although the formulations
have much improved over the years, because the dye works by coating
the outer hair surface the dye may reduce some of the shine from
natural hair. Many modern formulas get around this by adding other
chemicals with light reflective properties. One thing that has not
been improved significantly is the need for repeated application
to gradually increase the hair color change. Usually multiple applications
of metallic salt dyes are required to get the desired result and
then regular maintenance applications are needed to keep the color.
This disadvantage of metallic salt dyes has been turned into an
advantage by manufacturers. The makers often claim gradual gray
hair restoration properties for their product. There are relatively
few metallic salt dyes available today compared to a hundred years
ago, but the Grecian formulas for gray hair are such products.
There are some disadvantages of metallic salt dyes. There are relatively
few shades of metallic hair dyes available limited by the properties
of metal salts. However, the degree of color can be regulated by
the frequency of application. The more frequent the application,
correspondingly the stronger the color. These dyes tend to produce
quite dark and intense colors with frequent use. Metallic salt dyes
can interfere with permanent waving so there are restrictions on
using these dyes along with other forms of hair processing.
The advantages of metallic salt dyes include their ease of use
at home. The gradual change in color with repeated use is subtle
so friends and associates may not actually realize you have started
using hair dye. These dyes are relatively safe to use. Although
made from metals, the modern formulas are not absorbed through the
skin. There is usually no need for a patch test as it is extremely
rare to become sensitized to metallic salts.
To determine if hair has been colored by a metallic dye, mix 1
oz. of 20-volume peroxide with 20 drops of 28% ammonia. Submerge
20 strands of hair in the solution and let it sit at room temperature
for about 30 minutes. If the hair lightens rapidly, the hair contains
lead. If there is no reaction after 30 minutes, the hair contains
silver or bismuth. If the solution starts to boil and emits a foul
odor, the hair contains copper. Hair that has no metallic salts
on it should lighten only very slightly.
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