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Industrial & Marine Home | Coating Solutions Archived Issues | Spring 2003 Issue Home
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Dave
Schutz is an Industrial
and Marine Specialist.
He has been with
Sherwin-Williams for 21 years.
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When blasting is the required surface preparation for steel, why is abrasive size important? What is the relevance of the abrasive shape?QWhen blasting is the required surface preparation for steel, why is abrasive size important? What is the relevance of the abrasive shape? |
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Abrasive size, air pressure and distance
from the surface determine the depth
of profile and cleaning rate on steel surfaces.
Profile is important because an irregular
surface allows the coating to grip, providing
for better adhesion. Profile that is
too deep may leave exposed steel at the
peaks, resulting in rusting above the coating.
Two shapes of abrasive are available.
Shot is round and provides a surface that
appears peened. Grit is irregular in shape
with jagged edges. It provides better cutting
action than shot and creates a deeper
anchor pattern, which promotes adhesion
for the coating.
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We have built a new laboratory addition to our water treatment plant. The walls are concrete. In some areas of the lab we have used solventbased epoxy coatings on the walls, but we would like to use water-based epoxy on the new addition. Is there a waterbased epoxy that can be used to avoid the odor of solvent epoxy?
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Epo-Plex Multi-Mil is a high-build,
low-odor, water-based acrylic epoxy
that will meet your requirements. Surface
preparation is the key to a good system.
The surface must be clean, dry, sound and
offer sufficient profile to achieve adequate
adhesion. Minimum concrete cure is 28
days at 75 degrees F. Remove all curing
compounds, form release agents and other
foreign matter by sandblasting, shot blasting
or suitable chemical means, such as
muriatic acid etch. Rinse thoroughly to
achieve a pH between 6-10. For further
detail on concrete preparation refer to
SSPC-SP13 / NACE 6.
Epo-Plex Multi-Mil is available in
high-luster or low-luster finish. When
applied at 4-6 mils dft in one coat, it will
provide a tough, tile-like finish with excellent
resistance to abrasion, moisture, and
chemical attack.
One coat of masonry filler applied as
required to provide a smooth surface followed
by one or two coats of Epo-Plex
Multi-Mil applied at the recommended
DFT will provide excellent durability and
performance.
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Can you recommend a system that will offer adhesion to the exterior of stainless steel piping?
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Proper surface preparation is the key to
achieving good adhesion. First clean
the pipe per SSPC-SP1 solvent cleaning. A
water-soluble cleaner such as Extra Strength
Concentrated Prepaint Cleaner will remove
grease, oil, dirt and other surface contaminants.
Rinse thoroughly and allow the pipe
to dry before primer application.
Next apply a single coat of DTM Wash
Primer at 0.7-1.3 mils dft. The primer will
be ready to recoat in 2 hours when applied
at 77 degrees F and 50 percent relative
humidity. DTM Wash Primer can be topcoated
with a wide variety of finish coats
including acrylics, epoxies and urethanes to
meet your customer’s requirements.
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If you have a question you'd like considered for use in
"Ask the Experts," just submit it to Coatings Solutions,
21420 W. Greenfield Ave.,
New Berlin, WI 53146
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