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Paint Removal from CMU and Brick

Paint Removal from CMU and Brick. Kenneth A. Trimber KTA-Tator, Inc. Identify SSPC/NACE, ASTM, and ICRI standards and guidelines applicable to the removal of paint from CMU and brick substrates Describe various methods of paint removal, including advantages and disadvantages of each.

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Paint Removal from CMU and Brick

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  1. Paint Removal from CMU and Brick Kenneth A. Trimber KTA-Tator, Inc.

  2. Identify SSPC/NACE, ASTM, and ICRI standards and guidelines applicable to the removal of paint from CMU and brick substrates Describe various methods of paint removal, including advantages and disadvantages of each Paint Removal from CMU and Brick - Webinar Learning Objectives

  3. Questions to Ask During Project Design The following questions help to identify candidate coating 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?

  4. 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?

  5. Industry Standards and Guides

  6. Industry Standards and Guides (con’t) • SSPC-SP13/NACE No. 6, Surface Preparation of Concrete • SSPC-SP12/NACE No. 5, Surface Preparation and Cleaning of Metals by Water Jetting Prior to Recoating • ICRI Guideline No. 310.2 (formerly 03732), Selecting and Specifying Concrete Surface Preparation for Sealers, Coatings, and Polymer Overlays

  7. ICRI 310.2 – 9 Concrete Surface Profile (CSP) Coupons

  8. Industry Standards and Guides (con’t) • ASTM Standard Practices • ASTM D4258, Surface Cleaning Concrete for Coating • ASTM D4259, Abrading Concrete • ASTM D4260, Liquid and Gelled Acid Etching of Concrete • ASTM D4261, Surface Cleaning Concrete Masonry Units for Coating

  9. Surface Preparation/Cleaning Methods in Standards/Guides • Dry Abrasive Blast Cleaning • SSPC-SP13/NACE No. 6 • ICRI Guideline No. 310.2 • ASTM D4259 • Water Cleaning/Water Jetting • SSPC-SP13/NACE No. 6 • ICRI Guideline No. 310.2 • ASTM D4259 • Wet Abrasive Blast Cleaning • SSPC-SP13/NACE No. 6 • ASTM D4259

  10. 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 • Power Grinding/Sanding • SSPC-SP13/NACE No. 6 • ICRI Guideline No. 310.2 • ASTM D4259 • Scarifying/Grinding/Scabbling/Milling • ICRI Guideline No. 310.2 • ASTM D4259

  11. 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

  12. Surface Preparation/Cleaning Methods in Standards/Guides (con’t) • 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

  13. 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

  14. Abrasives propelledby compressed air Boiler slag, copperslag, nickel slag,garnet, crushed glass,sponge, walnut shells, others Very dusty – mayrequire containment system Dry Abrasive Blast Cleaning

  15. 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 Dry Abrasive Blast Cleaning (con’t)

  16. 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

  17. Expendable abrasive,same as dry blastcleaning Water is mixed withabrasive using: Water collar Special nozzle Special equipmentthat creates a slurry Wet Abrasive Blast Cleaning (con’t)

  18. Variation of wet abrasive 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

  19. Pressure categoriesdefined in SSPC-SP12/NACE No. 5, Surface Preparation and Cleaning of Metals by Water Jetting Prior to Recoating Despite the title, the methods suitable for CMU/brick Water Cleaning Low Pressure <5,000 psi High Pressure 5,000 to 10,000 psi

  20. 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

  21. 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

  22. Water temperature 250ºF and pressures <5,000 psi High temperature improves cleaning efficiency when removing all coating. High Temperature Low Pressure Water Cleaning (<5,000 psi)

  23. High temperature softens paint during removal High Temperature Low Pressure Water Cleaning (<5,000 psi) - con’t

  24. SSPC-SP12/NACE No. 5 Typically less water volume than low pressure cleaning methods Efficiently removes existing coating Water Jetting High Pressure 10,000 to 30,000 psi Ultra -High Pressure >30,000 psi

  25. 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

  26. Water Jetting (con’t) High Pressure 10,000 to 30,000 psi Ultra -High Pressure >30,000 psi

  27. Power sanding, power grinding, needle gunning, rotopeening Sanding and grinding remove paint with less damage to substrate than impact methods Vacuum shrouding available Power Tool Cleaning

  28. Power tool cleaning best used for localized removal Sanding methods good for feathering Power Tool Cleaning (con’t)

  29. Chemical stripping effectively removes existing paint Biodegradable strippers are available that do not contain methylene chloride or caustic materials Chemical Stripping

  30. 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

  31. Stripper and coating are removed by scraping, bucket and sponge, or pressure washing Chemical Stripping – con’t

  32. Depending on results, a second application may be necessary Chemical Stripping – con’t

  33. Second application essentially removes all coating Chemical Stripping

  34. 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?

  35. Practical Use of Candidate Surface Preparation Methods 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, but it is not commonly used for this purpose. 2 – Roughening created by power tool cleaning is dependent on the tool being used, ranging from slight roughening with power sanding to heavy roughening with power impact tools. 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 – 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, but this is only practical for small localized areas.

  36. Practical Use of Candidate Surface Preparation Methods .

  37. Practical Use of Candidate Surface Preparation Methods 2 – Roughening created by power tool cleaning is dependent on the tool being used, ranging from slight roughening with power sanding to heavy roughening with power impact tools. 3 – Slight to heavy roughening may occur

  38. Practical Use of Candidate Surface Preparation Methods

  39. Practical Use of Candidate Surface Preparation Methods 3 – 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 – 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, but this is only practical for small localized areas.

  40. Practical Use of Candidate Surface Preparation Methods

  41. 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)

  42. Additional Information • Paper associated with the webinar to be published in Durability + Design daily e-news - week of November 1, 2010 • SSPC 2011 – One day seminar on commercial painting – problems with painting CMU, surface preparation, application, and paint systems Feb 1, 2001

  43. Paint Removal from Masonry Substrates Webinar - Questions

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