Is Wall Paint?
abundance and widespread use of paint in our daily lives makes it
easy to take paint for granted. A look at the chemistry of paint leads
to a better appreciation of its complexities.
is a liquid composition that dries to an opaque film. It is composed
of four basic types of ingredients: pigments, which are powders
that give opacity and color; binders, which act like glue to hold
the pigments together and cause the film to adhere to the surface
being painted; liquids, which make the paint thin enough to spread
on a surface, and additives, which perform special functions such
as thickening, reducing mildew, and more.
are generally classified as either solvent-borne or waterborne.
Solvent-borne wall paints, such as oil paints, use a petroleum derivative
(for example, mineral spirits) as the solvent. Waterborne paints
wall coatings prevailed from prehistoric cave paintings up to medieval
wall paintings. Natural proteins were used as binders for the pigments.
Tempera used egg whites as a binder; distemper, a similar waterborne
paint, used animal glues from hides and hoofs. Whitewash used milk
casein to bind lime (calcium hydroxide) onto Tom Sawyer's fictional
fence. But all these exhibited poor washability and durability.
Linseed-oil-bound pigments -- used by the ancient Egyptians, early
Romans and renaissance artists such as daVinci and Michelangelo
-- were more durable, but were scarce until the linen industry expanded
to provide ample flax seed, from which linseed oil was pressed.
Hardening of the soft linseed oil films by rosin and adding volatile
turpentine from the naval stores industry enhanced varnishes for
Stradivarius violins, fine furniture and wooden floors. Turpentine
was the only historic volatile organic solvent to control paint
viscosities until the coke and petroleum industries distilled various
separate crafts came together only in the 1930s, when brilliant
exterior waterborne paints enhanced and survived the 1933 Century
of Progress Exposition in Chicago and the 1939-40 World's Fair in
New York City.
Was Kem-Tone Paint Different?
chemists used science to combine two chemical opposites--oil and
water. Their chemical innovation was to emulsify, in an aqueous
system, traditional solvent-borne binders with casein and other
traditional paint ingredients. The binders were casein, linseed
oil and, later, tall oil (obtained from wood pulp). This technique
set a new standard for the improvement of water-based paints. Eventually,
as the product evolved, newly developed synthetic binders replaced
the ones used in the original Kem-Tone paint.
paints generally contain mineral spirits to thin the paint and make
it "brushable." In contrast, Kem-Tone paint could be
diluted with water. The Kem-Tone paint formulation consisted
of many different ingredients.
Muss, No Fuss, No Bother
paint, which augmented Sherwin-Williams' family of "Kem" (standing
for chemically evolved material) products, was the first multi-million-gallon,
commercially accepted interior wall paint emulsified in water. The
flat, interior finish covered with only a single coat, dried in
one hour, had greatly reduced paint odor, and could be washed without
removing the color. After painting, cleanup was easily accomplished
with soap and water. These benefits were summarized in the advertising
slogan, "No Muss, No Fuss, No Bother."
paint's ease of application was enhanced by the introduction of
the Roller-Koater paint roller. Inexperienced painters found
that the applicator was faster to use than brushes and provided
more even coverage. This made it easier for homeowners to become
do-it-yourself painters -- an attractive alternative during the
labor shortages of World War II.
paint had another great advantage. It completely covered wallpaper,
plaster, and painted walls, without requiring messy primers, sealers
or thinners. Soon Kem-Tone and other waterborne paints
supplanted wallpaper as the decorative wall finish of choice in
the United States.
introduction of Kem-Tone paint in 1941 was the milestone
that showed the viability of durable, washable water-based paint
and led the way for future improvements. For example, after World
War II, the Dow Chemical Company searched for ways to use its styrene-butadiene
polymer (40 parts styrene, 60 parts butadiene), which it had developed
for tires during the war. The search led Dow to develop styrene-butadiene
latex (60 parts styrene, 40 parts butadiene) as a binder in water-borne
binder helped to create a new Sherwin-Williams product: latex paint.
In the late 1940s, the company introduced Super Kem-Tone
paint, which used styrene-butadiene latex as the principal, but
not sole, binder. This significantly improved the adhesion and durability
of waterborne paints.
the 1940s, paints emulsified in water have passed through several
additional phases. Styrene-butadiene latex paints yielded to new
improvements, such as vinyl acrylic and acrylic latex binders for