ILLUMINATION AND VISIBILITY
White and light-tinted coatings applied to ceilings
and walls reflect both natural and artificial light and
help brighten rooms and increase visibility. On the
other hand, darker colors reduce the amount of
reflected light. Flat coatings diffuse, soften, and
evenly distribute illumination, whereas gloss finishes
reflect more like mirrors and may create glare. Color
contrasts improve visibility of the painted surface,
especially when paint is applied in distinctive patterns.
For example, white on black, white on orange, or
yellow on black can be seen at greater distances than
single colors or other combinations of colors.
IDENTIFICATION AND SAFETY
Certain colors are used as standard means of
identifying objects and promoting safety. For
example, fire protection equipment is painted red.
Containers for kerosene, gasoline, solvents, and other
flammable liquids should be painted a brilliant yellow
and marked with large black letters to identify their
contents. The colors of signal lights and painted signs
help control traffic safely by providing directions and
other travel information.
TYPES OF COATINGS
LEARNING OBJECTIVE: Upon completing
this section, you should be able to identify the
types of structural coatings and finishes, and
the general characteristics of each.
As a Builder, you must consider many factors
when selecting a coating for a particular job. One
important factor is the type of coating, which depends
on the composition and properties of the ingredients.
Paint is composed of various ingredients, such as
pigment, nonvolatile vehicle, or binder, and solvent,
or thinner. Other coatings may contain only a single
In this section, well cover the basic components
of paintpigment, vehicles, and solventsand
explain the characteristics of different types of paint.
Paint is composed of two basic ingredients:
pigment and a vehicle. A thinner may be added to
change the application characteristics of the liquid.
PIGMENT. Pigments are insoluble solids,
ground finely enough to remain suspended in the
vehicle for a considerable time after thorough stirring
or shaking. Opaque pigments give the paint its hiding,
or covering, capacity and contribute other properties
(white lead, zinc oxide, and titanium dioxide are
examples). Color pigments give the paint its color.
These may be inorganic, such as chrome green,
chrome yellow, and iron oxide, or organic, such as
toluidine red and phthalocyanine blue. Transparent or
extender pigments contribute bulk and also control the
application properties, durability, and resistance to
abrasion of the coating. There are other special-
purpose pigments, such as those enabling paint to
resist heat, control corrosion, or reflect light.
VEHICLES, OR BINDERS. The vehicle, or
binder, of paint is the material holding the pigment
together and causing paint to adhere to a surface. In
general, paint durability is determined by the
resistance of the binder to the exposure conditions.
Linseed oil, once the most common binder, has been
replaced, mainly by the synthetic alkyd resins. These
result from the reaction of glycerol phthalate and an
oil and may be made with almost any property desired.
Other synthetic resins, used either by themselves or
mixed with oil, include phenolic resin, vinyl, epoxy,
urethane, polyester, and chlorinated rubber. Each has
its own advantages and disadvantages. When using
these materials, it is particularly important that you
exactly follow the manufacturers instructions.
SOLVENTS, OR THINNERS. The only
purpose of a solvent, or thinner, is to adjust the
consistency of the material so that it can be applied
readily to the surface. The solvent then evaporates,
contributing nothing further to the film. For this
reason, the cheapest suitable solvent should be used.
This solvent is likely to be naphtha or mineral spirits.
Although turpentine is sometimes used, it contributes
little that other solvents do not and costs much more.
Synthetic resins usually require a special
solvent. It is important the correct one be used;
otherwise, the paint may be spoiled entirely.
Paints, by far, comprise the largest family of
structural coatings you will be using to finish
products, both interior and exterior. In the following