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Shotblasting
Cont.
Why
Prepare a Surface?
Most coating adhesion problems are not the fault of the coating,
but the result of poor surface preparation. Two conditions
must be met before any coating can achieve a good bond with
a concrete floor. First the surface must be chemically clean
of dirt and other contaminants. because it is porous, concrete
will hold chemicals, oils, fats or other penetrating substances
that can act as barriers and prevent coatings from sticking
properly. All these contaminants must be removed before applying
a coating. Secondly, the surface must be given a mechanical
etch or profile. Surface profile can be described as the miniature
ridges and valleys that give concrete the "teeth"
to form a successful bond. Without a good profile as a base,
the chances of coatings becoming chipped or breaking up altogether
are significantly increased and the life expectancy of the
floor is reduced.
Historical
Preparation Methods
Over the years, several methods have been developed to erode
or blast away the top crust of the concrete where the majority
of contaminants are found. The most popular chemical process
is acid etching. Mechanical processes include scarifying,
sand blasting, and high pressure water blasting. Each method
is different, but al are basically time consuming, labor intensive
procedures. Profiling results are not always consistent. And
there are some additional environmental problems posed by
hazardous chemicals or airborne dust.
Shotblasting
Is Fast, Clean and Effective
In the early 80's, The Wheelabrator Corporation© pioneered
the self-contained, portable shot blasting method of surface
preparation. The technique used the proven science of airless
shot blasting, and the technology was now applied to a mobile
machine for covering larger floor surfaces, both new and replacement.
In a very short time, Blastrac© portable abrasive equipment
has become the surface preparation process recommended most
by U.S. coating manufacturers. It is generally considered
the best and fastest way to remove old coatings and contaminants
and to prepare floors for seamless coatings. Shot Blast cleaning
is a "one step" method that strips, cleans and etches
all at once. It leaves the surface dry and chemically free
without generating dust pollution and it totally eliminates
any drying time required before coatings can be applied.
Controlling
Surface Profile
Different surfaces require different profiles. The type of
abrasive used, as well as how it is applied, significantly
influences overall preparation effectiveness. Blastrac©
equipment uses six sizes of steel shot ranging from .017"
to .046" diameter. This selection allows users to achieve
a very controlled and uniform surface texture. The majority
of urethane or light coating applications require smaller
grades of shot, where just a fine profile etch is needed.
For heavier coatings and overlayments such as epoxies, larger
shot will deliver a coarser profile for better bonding power.
In cases where contaminants have penetrated deeply, larger
shot will dig out more concrete for better cleaning. The travel
speed of the Blastrac unit can also be adjusted depending
on the required etch depth. The slower the machine travels,
the deeper the etch it creates.
Versatile
on Many Surfaces
The Blastrac© machine is primarily known as an all-purpose
cleaning and profiling tool for concrete floors, parking decks
or road surfaces. It can efficiently clean materials such
as painted striping, dirt, grime, old coatings and imbedded
chemical contaminants. But it can also be economically applied
for preparation of steel ship decks and petroleum storage
tanks. Another interesting outdoor application is found in
cleaning the stone facades or flagstone walkways of residential
units or commercial buildings.
For
more information on Blastrac© or Shotblasting give SCR
a call. 847-526-0600
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