Specifications

This book is about the selection,
use and maintenance of finishing
equipment: spray guns, tanks,
cups, hoses, compressors,
regulators, spray booths,
respirators, etc. It presumes that
you are familiar with standard
surface preparation techniques that
may be required before finishing
actually begins. It also presumes a
basic knowledge of the many
different types of paints and
coatings available.
Creating a perfect finish requires a
solid knowledge of surface
preparation, finishes and spray
painting equipment. The first two
are extensively covered in many
other books. The manufacturers of
paints and coatings have gone to
great length to publish information
on their new and existing products.
But, even an extensive knowledge
of surface preparation techniques
and paint chemistry is not enough
to assure a professional finish. The
finish must be applied by a spray
gun, and all the variables of its use
must be mastered.
The equipment necessary to apply
the finish – the spray gun, tank,
cup, regulator, hoses, compressor,
etc. – must all be matched to the
job as well as to each other. That
equipment must be used and
maintained properly, with an
appreciation of how and why it
works the way it does.
The moment of truth for any finish
happens when the trigger is pulled.
This book focuses on that moment.
Surface Preparation
The surface to be finished should
be well cleaned before painting. If
the paint manufacturer’s
instructions call for it, the surface
should be chemically treated. Use
a blow-off gun and tack rag to
remove all dust and dirt. No
amount of primer or paint will cover
up a badly prepared surface.
Plastic parts may contain static
electricity from the molding
process. This static attracts
particles of dust and dirt. Eliminate
them by treating with “destatisiz-
ing” air using a special blow-off
gun that imparts a neutral charge
to the airflow. A chemical anti-static
treatment is also available.
Paint Preparation
Today’s finishes are extremely
complex chemical formulations.
They include both solvent and
waterborne types. Some may
require the addition of solvents to
form the proper spraying viscosity.
Others may simply require the
addition of a second component at
a prescribed ratio to obtain
sprayable consistency. Many of
them also have hardeners or other
chemicals, added to them to insure
correct color match, gloss,
hardness, drying time or other
characteristics necessary to
produce a first class finish. Make
sure you are familiar with the
specific finish material data sheets
accompanying each material. Do
not mix materials from various
manufacturers. Read and follow
directions carefully.
All finish materials must also be
supplied with a Material Safety
Data Sheet (MSDS). This data
provides information on proper
handling and disposal of materials.
Many states require that MSDS be
kept on file by the user.
The first step is knowing the type
and color of paint the project
requires. With this determined,
follow the manufacturer’s
instruction for preparing it exactly.
If you have any doubts about how
to proceed, don’t guess! Contact
your paint supplier for help.
Improperly prepared paint will
never produce a good finish!
The chief characteristic that
determines the sprayablility of paint
and how much film may be applied
is its viscosity … or consistency.
Following the paint manufacturer’s
instructions will get you close, but
for professional results, use a
viscosity cup. It is a simple but very
accurate way to measure the
thickness of paint. With the cup,
you can thin or reduce the paint to
the precise consistency required by
the manufacturer.
Always prepare paint in a clean,
dust-free environment. Paint has a
remarkable ability to pick up dirt.
Dirty paint will not only clog your
spray gun, but it will also ruin your
paint job. Get in the habit of always
pouring paint into the cup or tank
through a paint strainer. Paint is
never as clean as it looks.
1. Introduction
3