Transcript Removing Coatings and Cleaning Masonry Substrates Kenneth A. Trimber KTA-Tator, Inc. Removing Coatings and Cleaning Masonry SubstratesWebinar Learning Objectives  Identify SSPC/NACE, ASTM, and ICRI standards.

Removing Coatings and Cleaning
Masonry Substrates
Kenneth A. Trimber
KTA-Tator, Inc.
Removing Coatings and Cleaning
Masonry SubstratesWebinar Learning Objectives
 Identify SSPC/NACE, ASTM,
and ICRI standards and
guidelines applicable to
cleaning and the removal of
paint from CMU and brick
substrates
 Describe various methods of
paint removal and cleaning,
including advantages and
disadvantages of each
Questions to Ask
During Project Design
The following questions help to identify
candidate coating cleaning or paint
removal methods for the project:
– Does all coating have to be removed, or just
loose coating?
– If all coating must be removed, can small
amounts still be permitted to remain in the
porosity of the block?
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Questions to Ask
During Project Design (con’t)
– Can roughening of the block or brick be
tolerated. If so, can it be heavy or only
slight?
– Can large volumes of water be tolerated
(environmentally and in terms of potential
water intrusion into the substrate)?
– Can airborne dust be tolerated?
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Industry Standards and Guides
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Industry Standards
and Guides (SSPC)
• SSPC-SP13/NACE No. 6, Surface Preparation of Concrete
– More of a Guide than a Standard
– Frequently references other SSPC and ASTM Standards
– Describes cleaning methods from air blow down and vacuum
cleaning to power tool cleaning, water jetting and abrasive blast
cleaning
• Standard will be revised in a joint effort between the SSPC Surface
Preparation Committee and the SSPC Commercial Coatings
Committee
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Industry Standards
and Guides (SSPC)
• SSPC-SP12/NACE No. 5, Surface Preparation and Cleaning of Metals
by Water Jetting Prior to Recoating – replaced with:
– SSPC-SP WJ-4/NACE WJ-4, Waterjet Cleaning of Metals –
Light Cleaning
– SSPC-SP WJ-3/NACE WJ-3, Waterjet Cleaning of Metals –
Thorough Cleaning
– SSPC-SP WJ-2/NACE WJ-2, Waterjet Cleaning of Metals –
Very Thorough Cleaning
– SSPC-SP WJ-1/NACE WJ-1, Waterjet Cleaning of Metals –
Clean to Bare Substrate
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SSPC Visual Guides for Surface
Cleanliness – Steel (not Concrete)
• SSPC Visual Reference
Photographs are well
established for the cleaning
of steel, but none exist for
the cleaning of concrete
• The SSPC Commercial
Coatings Committee will be
filling this void and
developing reference
photographs for the
preparation of concreteboth cleanliness and
roughness
Industry Standards
and Guides (ICRI)
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ICRI Guideline No. 310.2 (formerly 03732), Selecting and Specifying
Concrete Surface Preparation for Sealers, Coatings, and Polymer Overlays
Addresses water and detergent cleaning, acid etching, a variety of power
tool methods, abrasive blast cleaning, and flame blasting
ICRI 310.2 – 9 Concrete Surface Profile (CSP) Coupons
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Industry Standards
and Guides (ASTM)
• ASTM D4258, Surface Cleaning Concrete for Coating
– Broom cleaning, vacuum cleaning, air blast cleaning, water
cleaning, detergent cleaning, steam cleaning
• ASTM D4259, Abrading Concrete
– Power tool, water blast, and wet/dry abrasive blast cleaning
• ASTM D4260, Liquid and Gelled Acid Etching of Concrete
• ASTM D4261, Surface Cleaning Concrete Masonry Units for
Coating
– Same as D4269 with the addition of mechanical tool cleaning for
the removal of mortar spatter and efflorescence
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Surface Preparation/Cleaning
Methods in Standards/Guides
• Detergent Cleaning
– SSPC-SP13/NACE No. 6
– ICRI Guideline No. 310.2
– ASTM D4258, ASTM D4261
• Air Blast Cleaning, Water Cleaning, Steam Cleaning,
Vacuum Cleaning
– SSPC-SP13/NACE 6
– ASTM D4258, ASTM D4261
• Chemical Stripping
– Effective method of paint removal, but not addressed in the
standards/guides
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Surface Preparation/Cleaning
Methods in Standards/Guides (con’t)
• Acid Etching
– SSPC-SP13/NACE No. 6
– ICRI Guideline No. 310.2
– ASTM D4260
• Flame Cleaning
– SSPC-SP13/NACE No. 6
– ICRI Guideline No. 310.2
•
• Power Grinding/Sanding
– SSPC-SP13/NACE No. 6
– ICRI Guideline No. 310.2
– ASTM D4259
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Surface Preparation/Cleaning
Methods in Standards/Guides (con’t)
• Impact Power Tool Cleaning
– SSPC-SP13/NACE No. 6
– ICRI Guideline No. 310.2
– ASTM D4259
• Scarifying/Grinding/Scabbling/Milling
– ICRI Guideline No. 310.2
– ASTM D4259
• Water Cleaning/Water Jetting
– SSPC-SP13/NACE No. 6
– ICRI Guideline No. 310.2
– ASTM D4259
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Surface Preparation/Cleaning
Methods in Standards/Guides (con’t)
• Wet Abrasive Blast Cleaning
– SSPC-SP13/NACE No. 6
– ASTM D4259
•
• Dry Abrasive Blast Cleaning
– SSPC-SP13/NACE No. 6
– ICRI Guideline No. 310.2
– ASTM D4259
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Candidate Paint Removal
Methods for CMU/Brick
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Dry Abrasive Blast Cleaning
Wet Abrasive Blast Cleaning
Sodium Bicarbonate Blast Cleaning
Water Cleaning (Low Pressure <5,000 psi; High Pressure
5000 -10,000 psi)
High Temperature Pressure Water Cleaning (<5,000 psi)
Water Jetting (High Pressure 10,000 – 30,000 psi; UltraHigh Pressure (>30,000 psi)
Power Tool Cleaning
Chemical Stripping
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Dry Abrasive Blast Cleaning
 Abrasives propelled
by compressed air
 Very dusty – typically
requires containment
system
Dry Abrasive Blast Cleaning
 Boiler slag, copper
slag, nickel slag,
garnet, crushed glass,
sponge, walnut shells,
others
Dry Abrasive Blast Cleaning (con’t)
 Difficult to selectively
remove loose coating
 Elastomeric coatings can
be difficult to remove
due to bounce back of
the abrasive
 Potential for very heavy
roughening of the
substrate and damage
to mortar joints, especially
when trying to remove all
coating
Wet Abrasive Blast Cleaning
 Variation of dry
abrasive blast
cleaning
 Water is mixed
with the abrasive
to control dusting
 Same potential to
roughen the
substrate as dry
abrasive blast cleaning
Wet Abrasive Blast Cleaning (con’t)
 Expendable abrasive,
same as dry blast
cleaning
 Water is mixed with
abrasive using:
– Water collar
– Special injection nozzle
– Special equipment
that creates a slurry
Wet Abrasive Blast Cleaning (con’t)
Sodium Bicarbonate Blast
Cleaning
 Variation of wet or dry
abrasive blast cleaning
 Sodium bicarbonate
(baking soda) is the
abrasive
 Larger particle size than
household baking soda
 Good for removing
surface contamination,
graffiti, and efflorescence
Sodium Bicarbonate Blast
Cleaning – efflorescence (wet)
Sodium Bicarbonate Blast
Cleaning – fire restoration (dry)
Water Cleaning
Low Pressure <5,000 psi
High Pressure 5,000 to 10,000 psi
 Pressure categories
defined in
–
–
–
–
SSPC-SP WJ-4/NACE WJ-4
SSPC-SP WJ-3/NACE WJ-3
SSPC-SP WJ-2/NACE WJ-2
SSPC-SP WJ-1/NACE WJ-1
 Despite the titles, the
methods are suitable for
CMU/brick
Water Cleaning (con’t)
Low Pressure <5,000 psi
High Pressure 5,000 to 10,000 psi
 Will effectively remove
loose coating
 Zero degree rotating
tip improves efficiency
 Can remove all coating
given ample dwell time
 Generally 5.0 to 10.0
gal/min
Water Cleaning (con’t)
Low Pressure <5,000 psi
High Pressure 5,000 to 10,000 psi
 Potential for using large
amount of water,
especially for total coating
removal
 Increased dwell time for
total removal can lead to
water intrusion and
wetting of interior
surfaces
Water Cleaning (con’t)
Low Pressure <5,000 psi
High Pressure 5,000 to 10,000 psi
 When used for surface
cleaning, operator
discipline is required to
assure the complete
cleaning is achieved
High Temperature Low Pressure
Water Cleaning (<5,000 psi)
 Water temperature
250ºF and pressures
<5,000 psi
 High temperature
improves cleaning
efficiency when removing
all coating
 High temperature softens
paint during removal
High Temperature Low Pressure
Water Cleaning (<5,000 psi) - con’t
Water Jetting
High Pressure 10,000 to 30,000 psi
Ultra -High Pressure >30,000 psi
 Typically less water volume
than low pressure cleaning
methods
 Efficiently removes existing
coating, but can roughen
substrate
Water Jetting (con’t)
High Pressure 10,000 to 30,000 psi
Ultra -High Pressure >30,000 psi
 Integral vacuum
recovery system
improves housekeeping
and cleanup
Water Jetting (con’t)
High Pressure 10,000 to 30,000 psi
Ultra -High Pressure >30,000 psi
Power Tool Cleaning
 Power sanding, power
grinding, needle
gunning, rotopeening
 Vacuum shrouding
available
Power Tool Cleaning
 Sanding and grinding
remove paint with less
damage to substrate
than impact methods
Power Tool Cleaning (con’t)
 Power tool cleaning best
used for localized
removal
 Sanding methods good
for feathering
Chemical Stripping
 Chemical stripping
effectively removes
existing paint
 Biodegradable strippers
are available that do not
contain methylene
chloride or caustic
materials
Chemical Stripping – con’t
 Stripper is first
applied to the surface
by brush, roller, or
spray
 Dwell time depends
on coating type,
temperature and
thickness, but
typically overnight
Chemical Stripping – con’t
 Stripper and coating are
removed by scraping,
bucket and sponge, or
pressure washing
Chemical Stripping – con’t
 Depending on results, a
second application may
be necessary
Chemical Stripping
 Second application
essentially removes all
coating
Original Project Design
Questions
• Does all coating have to be removed, or just loose coating?
• If all coating must be removed, can small amounts still be
permitted to remain in the porosity of the block?
• Can roughening of the block or brick be tolerated. If so, can
it be heavy or only slight?
• Can large volumes of water be tolerated (environmentally and
in terms of potential water intrusion into the substrate)?
• Can airborne dust be tolerated?
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Practical Use of Candidate Surface
Preparation Methods
Paint Removal Methods1
Extent of Coating
Removal
Feasible
Partial
Dry abrasive blast
Wet abrasive blast
Sodium bicarb blast
Pressure water (<10k)
High temp water (<5k)
Water jetting (>10k)
Power tool cleaning
Chemical stripping
Total
Substrate
Roughening
Slight
to none
x
x
x2
x
x
x
x
x
x
x
Heavy
Extent of Paint
or Residue in
Porosity
Slight
x
x
x3
x4
x
Mod
Mod
x
x
none
x
x2
x2
x
x
x
Volume of
Water Used
x
x
x
x
x3
none
x5
Little
Much
x
x
x
x
x3
x4
Large
Quantity of
Airborne Dust
Generated
x3
x5
x
x2
none
none
x2
none
x
none
1 – This table represents the practical application of the various methods when used under normal operations, but it is
not absolute. For example, abrasive blast cleaning can partially remove existing coating from CMU or brick, and low
pressure water (5k) can remove all coating, but they are not commonly used in these ways.
2 – Sodium bicarbonate is best suited for surface cleaning rather than paint removal. It can be used wet or dry. If
used dry, a large quantity of airborne dust is created. When used wet, little to no dust is generated.
3 – Slight to heavy roughening may occur. Vacuum shrouding will significantly reduce the volume of water. Without
vacuum shrouding, the volume is greater, but typically not as high as pressure washing at < 10,000 psi.
4 – Roughening created by power tool cleaning is dependent on the tool being used, ranging from slight to no
roughening with power sanding to heavy roughening with power impact tools.
5 – A large volume of water is generated if the stripper is removed by pressure washing. Much less water is involved if
removed by scraping and sponge/water to flush the surface, but this is only practical for small localized areas.
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Productivity
Production rates for some of the methods
can be found in:
– Painting and Decorating Contractors of America
(PDCA) Estimating Guide, Volume 2, Rates and Tables
www.PDCA.org (314-514-7322)
– ICRI Guideline No. 310.2 (formerly 03732), Selecting
and Specifying Concrete Surface Preparation for
Sealers, Coatings, and Polymer Overlays
www.icri.org (847-827-0830)
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Additional Information
• A paper associated with the information in this
webinar was published in Durability + Design
Magazine – March/April 2011
• Sources of equipment and materials can be
found in the Durability + Design on-line Painting
Equipment and Supplies Buying Guide (under
the Buying Guides tab on the home page)
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Removing Coatings and Cleaning
Masonry Substrates - Questions
Kenneth Trimber 412-788-1300,x204
[email protected]