Surface Preparation for Resin Systems
Surface Preparation Guide
For Concrete, Wood, and Metal Substrates
I. GENERAL INFORMATION
Surface preparation is considered to be the most important step of any resinous
flooring application. Improper surface preparation could turn what seems to be a
simple process into a lengthy, difficult repair. The following conditions will dictate
the type of surface preparation:
A. Concrete Placement
1. Slab-on-grade or on the ground
a. A 10 mil minimum vapor barrier is necessary to prevent moisture vapor transmission.
An efficient puncture proof barrier is recommended.
b. Proper jointing will minimize cracking which could transmit through the resinous
flooring system.
2. Elevated Slabs
a. Pan construction should be vented.
b. Metal deck construction should be properly jointed to minimize cracking.
B. Curing and Finishing Techniques
1. Curing compounds, if used, must be mechanically removed from the concrete surface
prior to all resinous flooring applications.
2. Recommended techniques:
a. Wet cure
b. Light steel trowel finish to minimize laitance and provide hard surface
C. Age of Concrete
Concrete must be a minimum of 30 days old for resinous flooring applications. Primers
are now available which can be used on fresh (green) concrete on some installations.
Contact the technical department for details.
D. Previous Contamination can affect the bond of the resinous flooring and must
be removed. Types of contamination are:
1. Oil, grease, or food fats can usually be burned off with a flame gun or
removed with a commercial degreasing compound or solvent.
2. Curing compounds, sealers, and other laitance are best removed mechanically
with:
a. vacuum shot-blasting
b. scarifying
c. sand blasting
E. Present Condition
1. Test for moisture: Coating system bond failures on slabs on grade and elevated/lightweight
concrete caused by moisture vapor transmission are the industry's largest single
problem and result in extreme frustration from owners, clients, and contractors.
Epoxy.com recommends testing for moisture vapor transmission. The recognized
methods are:
a. ASTM-F-1869 Standard Test Method for Measuring Moisture Vapor Emission Rate
of Concrete Subfloor Using Anhydrous Calcium Chloride: The maximum allowed
water/vapor transmission rate is 3 pounds per 1,000 square feet per 24 hours.
b. ASTM F-2170 Standard Test Method for Determining Relative Humidity
in Concrete Floor Slabs Using In Situ Probes: This test measures the relative humidity
in the slab below the surface. If taken over a period of time, it will show the
rate of drying in the slab. The maximum relative humidity should be below 80%.
c. ASTM-D-4263 Plastic Sheet Test: This test gives an indication that
moisture may be present.
2. Moisture related failures can be prevented through:
a. Placing new concrete over an efficient vapor barrier.
b. Testing for moisture vapor transmission as prescribed above prior to resinous
flooring application.
c. Applying a moisture vapor transmission reduction system where moisture content
is too high for successful resinous flooring applications.
3. A clean surface is necessary to establish a strong bond between the resinous
flooring and concrete.
4. Resinous flooring systems are only as sound as the concrete they are applied
to. All unsound concrete should be repaired or replaced prior to resinous flooring
applications. Consult your Epoxy.com Technical Service Department for specific
information.
5. Resinous flooring materials should be applied to level concrete substrates. Grind
or fill high and low spots prior to application.
6. Repair cracks prior to resinous flooring applications.
F. Mechanical Prep vs. Acid Etching
Resinous flooring materials ideally bond to concrete with a rough, sand-paper finish.
This finish can be achieved by either acid etching or mechanical methods. The choice
of preparation is dictated by the factors above. Other factors which determine the
type of preparation include:
1. Ecological restrictions involved with waste removal which could prohibit the
use of acid etching and other chemical methods.
2. The type of resinous flooring material: It is recommended that concrete floors
be acid etched prior to application of polyester and vinyl ester flooring systems.
G. Acid Etching
The following steps are recommended for acid etching:
1. Dilute commercial muriatic acid with water using 1 part acid by volume to 3 parts
clean water by volume. Add the acid slowly taking care to avoid splashing. Workers
should be protected with safety glasses, rubber gloves, and boots. If skin or eye
contact occurs, rinse affected area thoroughly with clean water and follow Material
Safety Data recommendations.
2. Sprinkle acid solution onto the entire surface in order to allow the acid to
reach all areas of the concrete. Adequate coverage is approximately 75 ft?/gallon
of acid/water solution. Do not puddle and spread.
3. Scrub the acid solution into the concrete using a stiff bristle broom to remove
loose concrete and laitancy.
4. Before rinsing, look for areas where bubbling did not occur. These areas have
not been sufficiently cleaned and will require mechanical scarifying and additional
acid etching.
5. When the acid solution has stopped bubbling (usually after approximately 15 minutes),
rinse the floor thoroughly with water. Do not allow the floor to dry before rinsing
because the salts formed by the acid reaction may cause problems with the adhesion
and performance of the resinous flooring system. Test pH of the concrete surface
to verify that the concrete tests alkaline.
6. Finally, the floor should be dry mopped to remove standing water and dirt remaining
after the acid etching. Allow the floor to completely dry prior to the application
of any resinous flooring system. Failures can occur in resinous flooring system
applications due to moisture remaining in the substrate.
H. Mechanical Preparation
Contamination and other foreign materials must be mechanically removed to ensure
a satisfactory bond. All dust and debris must be thoroughly removed.
II. OLD CONCRETE
Old concrete surfaces must be structurally sound. Any unsound areas must be repaired
prior to proceeding with the resinous installation. For proper patching and repairing,
use Epoxy.com Technical Service Department. Remove existing paint, scale and loose
concrete by rough sanding, sandblasting, shot blasting, or grinding. In some cases
where plant conditions allow, a stripper may be used to remove excessive build-up
of paints or sealers.
Structurally sound concrete should be mechanically prepared to remove any contamination.
Vacuum shot blasting is the best method for achieving a good profile for bonding
and should be used where possible. Before installation of any Epoxy.com Product
the surface must be examined for moisture vapor transmission using:
ASTM-F-1869 Standard Test Method for Measuring Moisture Vapor Emission Rate of Concrete
Subfloor Using Anhydrous Calcium Chloride.
ASTM-F-2170 Standard Test Method for Determining Relative Humidity in Concrete Floor
Slabs Using In Situ Probes.
ASTM-D-4263 Standard Test Method for Indicating Moisture in Concrete by the Plastic
Sheet Method. This test is only an indication and should not be used to determine
moisture migration.
Other ASTM Tests which are applicable to concrete preparation are:
ASTM-D-4258 Standard Practice for Surface Cleaning Concrete for Coating
ASTM-D-4259 Standard Practice for Abrading Concrete
ASTM-D-4260 Standard Practice for Acid Etching Concrete
ASTM-D-4261 Standard Practice for Surface Cleaning Concrete Unit Masonry for Coating
ASTM-D-4262 Standard Test Method for Ph of Chemically Cleaned or Etched Concrete
Surfaces
ASTM-C-811 Standard Practice for Surface Preparation of Concrete for Application
of Chemical Resistant Resin Monolithic Surfacing
III. NEW CONCRETE
New concrete must be well cured and dry prior to coating. Allow to cure a minimum
of 28 days unless using green concrete primer. No curing agents or sealing compounds
should be used at any time prior to coating. A light steel trowel finish is recommended
when finishing the concrete surface.
Any oil, grease, laitance, or other foreign material must be removed. Steam clean
with a strong degreaser such as tri-sodium phosphate. Laitance and other foreign
material are best removed by mechanical methods such as vacuum blasting, scarification,
or grinding.
All new concrete can be acid etched or mechanically prepared by vacuum shotblasting,
sand blasting, scarifying, or grinding. Vacuum shot-blasting provides the cleanest
environmentally safe area during cleaning. It also provides a mechanically rough
surface to achieve a good bond.
When acid etching, use a 3 to 1 dilution of water to acid and follow directions
printed above.
Before the installation of any Epoxy.com resinous system, the surface should be
examined for moisture. Test for moisture vapor transmission using ASTM F-1869 Standard
Test Method for Measuring Moisture Vapor Emission Rate of Concrete Subfloor Using
Anhydrous Calcium Chloride. The maximum allowable rate is 3 pounds per 1,000 square
feet per 24 hours.
Another procedure that helps determine slab dryness is ASTM-F-2170 Standard
Test Method for Determining Relative Humidity in Concrete Floor Slabs Using In Situ
Probes. Maximum allowable R.H. for protimeter test is 80%.
WOOD SUBSTRATES
I. GENERAL INFORMATION
Resinous flooring must always be applied directly to exterior grade plywood with
extended glue line INTERIOR GRADE PLYWOOD delaminates easily and SHOULD NOT BE USED
as it could result in a failure of the resinous flooring system. MARINE GRADE
PLYWOOD contains moisture repellants which could cause a darkening of the
resinous flooring system and SHOULD NOT BE USED. All plywood must be completely
free of all waxes, varnishes, or other foreign materials.
A. Plywood used to cover existing wood floors
1. Clean and fasten existing wood floor to the floor joists.
2. If the floor is completely sound, fasten ? Exterior grade plywood "C"
plugged with an extended glue line to the existing floor. Stagger the plywood
for strength.
3. ¾" DFPA Exterior or ?" DFPA Underlayment grade plywood with exterior
glue line must be used if the existing floor cannot be cleaned, or is not sound.
4. All plywood must be completely free of all waxes, varnishes, or other foreign
materials.
5. Secure plywood with exterior glue.
6. Use Ring Shank or Wood Screws at six (6) inch centers around panel
edges and support.
7. Stagger all panel joints, fill joints with epoxy filler, and cover joints with
fiberglass cloth and epoxy resin.
8. Lightly sand the floor surface to insure proper adhesion of the resinous flooring
system.
9. Prime surface with appropriate primer prior to system application. Surface may
require double priming due to porosity of plywood.
B. Plywood used for new construction (plywood is laid directly on the joist)
1. Exterior grade plywood "C" plugged with an extended glue line
must be used.
All plywood must be completely free of all waxes, varnishes, or other foreign materials.
2. Use Ring Shank or Wood Screws at six (6) inch centers around panel
edges and support.
3. Stagger all panel joints, fill joints with Epoxy.com Product #703.
For outdoor applications cover joints with fiberglass cloth and the membrane system
being used with the outdoor system.
4. Lightly sand the floor surface to insure proper adhesion of the resinous flooring
system.
5. Remove all dust with a vacuum cleaner.
C. Applications with waterproofing:
1. After preparing the floor surface as prescribed above, caulk all joints with
Epoxy.com Product #703 for indoor systems. For outdoor systems
use the membrane used with the Epoxy.com outdoor system.
2. Apply the waterproofing membrane as specified.
I. Preliminary Preparation
A. Metal substrates must be structurally sound prior to any resinous system being
applied.
B. Remove all foreign materials such as oil and grease with solvents or other degreasing
compounds.
C. All scaling and rust must also be removed mechanically by sanding, sandblasting,
or abrasion.
II. Treat the blasted/abraded surface with a phosphoric acid solution as described
below in order to prevent rust formation if the surface is left exposed for some
time prior to application of the resin system.
A. Always use a 10% solution of Phosphoric Acid.
B. Mix acid solution in either glass, plastic, or earthen containers (never use
metal containers), by adding Phosphoric Acid to water. NEVER VICE-VERSA due to heating
or splashing which may occur.
Workers should be protected with safety glasses, rubber gloves, and boots. If skin
or eye contact occurs, rinse affected area thoroughly with clean water and follow
Material Safety Data recommendations.
C. Apply phosphoric acid solution by either paint brush or rubber squeegee and allow
metal surface to AIR DRY.
DO NOT FLUSH METAL SURFACE WITH WATER.
III. Protect surface from contamination until the primer is applied.
IV. Wipe metal surface with MEK solvent immediately before primer application.