Methods for the Detection of Soluble Salts William D. Corbett KTA-Tator, Inc.
Removing Coatings and Cleaning Masonry Substrates Kenneth A. Trimber KTA-Tator, Inc.
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Transcript of Removing Coatings and Cleaning Masonry Substrates Kenneth A. Trimber KTA-Tator, Inc.
Removing Coatings and Cleaning Masonry
Substrates
Kenneth A. TrimberKTA-Tator, Inc.
Removing Coatings and Cleaning
Masonry Substrates- Webinar 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 concrete-both cleanliness and roughness
Industry Standards and Guides (ICRI)
• 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/guides11
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
• 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;
Ultra-High Pressure (>30,000 psi)• Power Tool Cleaning• Chemical Stripping
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Dry Abrasive Blast Cleaning
Abrasives propelledby compressed air
Very dusty – typicallyrequires containment system
Dry Abrasive Blast Cleaning
Boiler slag, copperslag, nickel slag,garnet, crushed glass,sponge, walnut shells, others
Dry Abrasive Blast Cleaning (con’t)
Difficult to selectivelyremove loose coating
Elastomeric coatings canbe difficult to removedue to bounce back ofthe abrasive
Potential for very heavyroughening of thesubstrate and damageto mortar joints, especially when trying to remove all coating
Wet Abrasive Blast Cleaning
Variation of dryabrasive blastcleaning
Water is mixed with the abrasiveto control dusting
Same potential toroughen the substrate as dryabrasive blast cleaning
Wet Abrasive Blast Cleaning (con’t)
Expendable abrasive,same as dry blastcleaning
Water is mixed withabrasive 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 dryabrasive blast cleaning
Sodium bicarbonate (baking soda) is the abrasive
Larger particle size thanhousehold 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 categoriesdefined 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 removeloose coating
Zero degree rotatingtip improves efficiency
Can remove all coatinggiven ample dwell time
Generally 5.0 to 10.0gal/min
Water Cleaning (con’t) Low Pressure <5,000 psi
High Pressure 5,000 to 10,000 psi
Potential for using largeamount of water, especially for total coatingremoval
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
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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.
Paint Removal Methods1 Extent of Coating Removal Feasible
Substrate Roughening
Extent of Paint or Residue in
Porosity
Volume of Water Used
Quantity of Airborne Dust
Generated
Partial Total Slight to none
Heavy Slight Mod Mod Large Little Much
Dry abrasive blast x x x none x
Wet abrasive blast x x x x x
Sodium bicarb blast x2 x x2 x2 x2 x2
Pressure water (<10k) x x x x none
High temp water (<5k) x x x x x none
Water jetting (>10k) x x x3 x3 x x3 x3 none
Power tool cleaning x x 4 x 4 x none x
Chemical stripping x x x x5 x5 none
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 Tableswww.PDCA.org (314-514-7322)
– ICRI Guideline No. 310.2 (formerly 03732), Selecting and Specifying Concrete Surface Preparation for Sealers, Coatings, and Polymer Overlayswww.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]