Surface Preparation


Proper surface preparation can improve the outcome of your coating system. The steps below are provided for assistance in properly preparing various common substrates before coating. Following these guidelines will help ensure sufficient adhesion of the coating and can help prolong the life of the coating system.

Surface Types

Surface Preparation

Surface Types & Preparation Tips

Aluminum

Ensure that all oil, grease, dirt, oxide and other contaminants have been removed by cleaning per SSPC-SP1, Solvent Cleaning.

Block (Cinder and Concrete)

Surface must be free of laitance, concrete dust, dirt, form release agents, moisture curing membranes, loose cement, and hardeners. All loose mortar and foreign material should be removed from block.

  • Commercial detergents and abrasive blasting may be required to prepare the surface on tilt-up and poured-in-place concrete.
  • Allow concrete and mortar to cure at least 30 days at 75ºF.
  • Surface pH of the surface must be between 6 and 9.
  • Fill air pockets, bug holes, and other spaces with a cement patching compound.
Brick

Brick must be free of all foreign matter including dirt and loose or excess mortar.

  • Allow brick to weather for at least one year followed by wire brushing to remove efflorescence.
  • Bare brick must be treated with one coat of Masonry Conditioner.
Concrete

The procedures below are intended to help assure optimum performance of the coating system and suitable coating adhesion to concrete:

  1. Although moisture seldom drops below 15% in concrete, concrete should be free of moisture as much as possible (Reference ASTM D4263). To test for moisture or dampness, tape the 4 edges of a 2-foot by 2-foot plastic sheet (4 mils thick) on the bare surface, sealing all edges. Wait at least 16 hours before inspecting. If moisture, discoloration, or condensation appears on the concrete or the underside of the plastic, the source must be located and the cause corrected prior to painting.
  2. Surface pH should be between 6 and 9. Concrete should be cured prior to coating application; it should be poured and aged at a material temperature of at least 75ºF for at least 30 days.
  3. Material, air, and surface temperature must remain at 50ºF (10ºC) or above during application and until the coating is cured.
  4. Remove all dirt, oil, grease, loose or peeling paint, oil, tar, glaze, laitance, loose mortar, efflorescence, and cement with suitable mechanical or chemical method (see methods described below). Any form release agents, curing compounds, hardeners, sealers, and other concrete treatments must be compatible with the coatings, or be removed.
  5. Any imperfection may require filling with a material compatible with Conco Paints coatings.
Concrete (Blast Cleaning Reference ASTM D4259)

Brush Blasting or Sweep Blasting (Includes dry blasting, water blasting, water blasting with abrasives, and vacuum blasting with abrasives)

  1. Use oil and sand-free air with 16-30 mesh.
  2. Remove all surface contamination (ref. ASTM D4258). See section below entitled "Concrete (Surface Cleaning)."
  3. Stand about 2 feet from the surface to be blasted.
  4. Move nozzle at a uniform rate.
  5. Bug holes must be opened and laitance removed.
  6. Surface must have a texture similar to that of medium grit sandpaper, and must be clean and dry (moisture check: ref. ASTM D4263).
  7. Remove dust and loose particles from surface with vacuum or by blowing (ref. ASTM D4258).
Concrete (Acid Etching)

The procedures below are intended to help assure optimum performance of the coating system and suitable coating adhesion to concrete:

  1. Ensure that all surface contamination has been removed (ref. ASTM D4258).
  2. Use clean water to wet the surface.
  3. Spread a 10-15% Muriatic Acid or 50% Phosphoric Acid solution over the surface at the rate of one gallon per 75 square feet.
  4. Use a stiff brush to scrub the surface.
  5. Allow sufficient time for scrubbing until bubbling stops.
  6. If bubbling does not occur, the surface is contaminated with a concrete treatment, oil, or grease which is interfering with proper etching. Remove the contamination with a suitable cleaner (ref. ASTM D4258, or see "Concrete {Surface Cleaning)" instructions below) and then etch the surface.
  7. Rinse the surface two or three times, ensuring that the acid/water mixture is completely removed after each rinse.
  8. Once completed, the surface should have a texture like that of medium grit sandpaper.
  9. If an acceptable texture cannot be achieved after one application, it may be necessary to repeat this step several times. Make sure the pH (ref. ASTM D4262) of the surface is neutral and that the surface is clean and sound by applying a 3% solution of trisodium phosphate or similar alkali cleaner. Flush with clean water after application of the cleaner.
  10. Allow surface to dry and check for moisture (ref. ASTM D4263).
Concrete (Power Tool Cleaning or Hand Tool Cleaning)
  1. With a power grinder or needle gun, equipped with a suitable grinding stone of appropriate size and hardness, remove loose mortar, concrete, fins, projections, and surface contaminants. Hand tools may also be used.
  2. Blow down or vacuum to remove loose particles and dust from the surface (ref. ASTM D4258, or see "Concrete (Surface Cleaning}" section below).
  3. Although moisture seldom drops below 15% in concrete, concrete should be free of moisture as much as possible (Reference ASTM D4263). To test for moisture or dampness, tape the 4 edges of a 2-foot by 2-foot plastic sheet (4 mils thick) on the bare surface, sealing all edges. Wait at least 16 hours before inspecting. If moisture, discoloration, or condensation appears on the concrete or the underside of the plastic, the source must be located and the cause corrected prior to painting.
Concrete (Surface Cleaning)

The surface to be coated must be clean and free of contaminants, oil, loose cement, mortar, and grease. Vacuum cleaning, broom cleaning, water cleaning, air blast cleaning, and steam cleaning are suitable as outlined in ASTM D4258.

Concrete curing compounds, hardeners, and form release agents may not be compatible with recommended coatings. To test compatibility, apply a 2-3 square foot area with the coating system, and allow concrete to dry one week before testing adhesion per ASTM D3359. Surface preparation methods as outlined in ASTM D4259 are required if the coating system is incompatible.

Cement Composition Sliding/Panels

Ensure that all surface contamination has been removed by washing with an appropriate cleaner. Rinse thoroughly and allow to dry. Any existing checked or peeling paint should be scraped and sanded to a sound surface. Glossy surfaces should be sanded dull. If necessary, pressure clean with a minimum of 2100 psi to remove all dirt, dust, oil, grease, laitance, loose particles, foreign material, and peeling or defective coatings. Allow the surface to dry thoroughly. If the surface is new, test it for pH, many times the pH may be 10 or higher.

Copper

Remove all oxide, oil, grease, dirt, and surface contaminants by cleaning per SSPC-SP 2, Hand Tool Cleaning.

  • Commercial detergents and abrasive blasting may be required to prepare the surface on tilt-up and poured-in-place concrete.
  • Allow concrete and mortar to cure at least 30 days at 75ºF.
  • Surface pH of the surface must be between 6 and 9.
  • Fill air pockets, bug holes, and other spaces with a cement patching compound.
Drywall (Interior / Exterior)

Drywall should be clean and dry. Tape and cover joints with a joint compound. All nail heads must be set and spackled. Make sure all spackled nail heads and tape joints are sanded smooth and all dust removed prior to painting. For exterior surfaces, spackle with exterior grade compounds.

Exterior Composition Board (Hardboard)

Exterior composition board siding (hardboard) must be thoroughly cleaned and primed with an alkyd primer, whether factory primed or unprimed. Some composition boards may emit a waxy material that must be removed with a solvent prior to coating.

Galvanized Metal

Galvanized metal must weather at least 6 months before coating. Solvent clean per SSPC-SP1, then prime as required. When weathering is not possible or the surface has been treated with chromates or silicates, first Solvent Clean per SSPC-SP1 and apply a test area, priming as required. Allow the coating to dry at least one week before testing for adhesion. If adhesion is inadequate, Brush Blast per SSPC-SP7 is necessary to remove these treatments.

Plaster

Allow to dry and cure thoroughly for at least 30 days prior to painting. Bare plaster must be cured and hard before application. Damaged areas must be repaired with an appropriate patching material. Treat textured, soft, porous, or powdery plaster with a solution of 1 pint household vinegar to 1 gallon of water. Repeat until the surface is hard. Rinse with clear water and allow to dry. The room must be ventilated while drying. Rooms must be heated in cold, damp weather.

Previously Coated Surfaces

Remove all dust, oil, wax, grease, loose paint, mill scale, rust, dirt, mold, mildew, mortar, efflorensence, sealers, and other surface contaminants. Dull glossy surfaces prior to painting. Use an appropriate primer to spot prime any bare ares. Maintenance painting will frequently not permit or require complete removal of all old coatings prior to repainting. Thorough washing with an abrasive cleanser will clean and dull in one operation, or, wash thoroughly and dull by sanding. Be advised that any coatings left on the surface to be painted may compromise the service length of the system. Check for compatibility by applying a test patch of the recommended coating system, covering at least 2 to 3 square feet. Allow to dry one week before testing adhesion per ASTM D3359. If coating system is incompatible, complete removal of previous coating(s) is required (per ASTM 4259, see "Concrete (Blast Cleaning)" above).

Steel (Structural Plate)

Clean steel using one or more of the nine surface preparations described below. Established by the Steel Structures Council in 1952, these methods are used throughout the world for describing methods for cleaning structural steel. Visual standards are available through the Steel Structures Painting Council; ask for SSPC-Vis 1-67T.

Steel (Solvent Cleaning)

This method is suitable for removal of all visible oil, drawing and cutting compounds, grease, soil, and other soluble contaminants. Mill scale and rust cannot be removed by solvent cleaning. Rags and cleaning solution should be changed frequently so that deposits of oil and grease are not spread over additional areas in the cleaning process. Allow sufficient ventilation.

Steel (Hand Tool Cleaning)

Hand Tool Cleaning will remove all loose rust, loose mill scale, and other undesired foreign matter. Adherent mill scale, paint, and rust are not able to be removed by this process. Make sure all visible grease, oil, salts, and soluble welding residues have been removed before hand tool cleaning by the methods outlined in SSPC-SP 1.

Steel (Power Tool Cleaning)

All loose rust, loose mill scale, loose and other detrimental foreign matter can be removed by power tool cleaning. Adherent mill scale, paint, and rust are not able to be removed by this process. Make sure all visible grease, oil, salts, and soluble welding residues have been removed prior to power tool cleaning by the methods outlined in SSPC-SP 1.

Steel (White Metal Blast Cleaning)

When viewed without magnification, a White Metal Blast Cleaned surface should be free of any visible grease, oil, dust, dirt, mill scale, paint, rust, oxides, corrosion products, and other foreign matter. Visible deposits of grease or oil must be removed prior to blast cleaning by any method specified in SSPC-SP 1 or other agreed upon methods.

Steel (Commercial Blast Cleaning)

Staining to be cleaned may consist of light shadows, slight streaks, or minor discolorations caused by stains of rust, mill scale, or previously applied paint. However, steel must not be stained on more than 33% of each square inch of surface area. Visible deposits of grease or oil must be removed prior to blast cleaning by any method specified in SSPC-SP 1 or other agreed upon methods.

Steel (Brush-Off Blast Cleaning)

When viewed without magnification, a Brush-Off Blast Cleaned surface should be free of any visible grease, oil, dust, dirt, loose mill scale, loose paint, and loose rust. Mill scale, paint, and rust that is tightly adhered to the surface may remain even after Brush-Off Blast Cleaning. Visible deposits of grease or oil must be removed prior to blast cleaning by any method specified in SSPC-SP 1 or other agreed upon methods.

Steel (Power Tool Cleaning to Bare Metal)

When viewed without magnification, a metallic surface prepared according to this specification should be free of any visible grease, oil, dust, dirt, mill scale, paint, rust, oxides, corrosion products, and other foreign matter. Small residues of rust and paint may be left in the lower portions of pits if the original surface is pitted. Visible deposits of grease or oil must be removed prior to power tool surface preparation by any method specified in SSPC-SP 1, Solvent Cleaning, or other agreed upon methods.

Steel (Near-White Blast Cleaning)

When viewed without magnification, a Near-White Blast Cleaned surface should be free of any visible grease, oil, dust, dirt, mill scale, paint, rust, oxides, corrosion products, and other foreign matter, with the exception of staining. Visible deposits of grease or oil must be removed prior to blast cleaning by any method specified in SSPC-SP 1 or other agreed upon methods.

Steel (Water Blasting)

Method of cleaning steel to remove dirt, oil, grease, loose rust, loose mill scale, and loose paint using water at pressures of 2,000 to 2,500 psi at a flow of 4 to 14 gallons per minute.

Stucco

Ensure that the surface is clean and free of any loose stucco, and that surface pH is between 6 and 9. The surface may be painted after 30 days if recommended procedures for applying stucco are followed, and normal drying conditions exist.

Wood (Exterior)

Wood must be clean and dry. Ensure that knots and pitch streaks are scraped, sanded, and spot primed before a full priming coat is applied. Patch all nail holes and imperfections with a wood filler or putty and sand smooth. Prime and paint as soon as possible after surface prep. Caulk should be applied after priming.

Wood (Interior)

Store finishing lumber and flooring in dry, warm rooms to prevent absorption of moisture, shrinkage, and roughening of the wood. Sand surfaces smooth, taking care to sand with the grain. Surface imperfections should be corrected and cleaned prior to painting.

Vinyl Siding

Thoroughly cleanse vinyl siding by scrubbing with a warm, soapy water solution. Rinse carefully and allow to dry.