Long-term coating performance depends directly on proper surface preparation. When surfaces are inadequately prepared, adhesion is compromised and overall service life is reduced Industry studies commonly report that a large percentage of coating failures—sometimes estimated at up to 80%—are linked to inadequate surface preparation that compromises adhesion. Selecting and properly implementing the correct preparation method ensures coating adhesion and maximizes the durability of the coating system.
The appropriate preparation method is influenced by substrate type (Figure 1), environmental exposure, coating system selection, and expected service life. Budget considerations, degree of contamination, and jobsite conditions must also be evaluated. This guide serves as a reference for preparation methods and assists in determining the proper approach for specific project conditions.
Labor associated with preparation and application typically represents the largest portion of total project cost, often exceeding material costs. Labor costs have increased at a faster rate than material costs in recent years. These economic factors further emphasize the importance of proper specification, inspection, and quality control to achieve long-term performance.
All surfaces must be properly cured, clean, dry, and free of any contaminants that can interfere with coating adhesion. Repair cracks, voids, and imperfections with suitable patching compounds and allow repairs to cure prior to coating application.
IMPORTANT: For exterior applications, primers should be topcoated within 14 days. If this window is exceeded, clean surfaces thoroughly before applying the finish coat.Gaps between windows, doors, trim, and other through-wall openings should be filled with the appropriate caulk or sealant after priming the surface.
WARNING! If you scrape, sand or remove old paint, you may release lead dust. LEAD IS TOXIC. EXPOSURE TO LEAD DUST CAN CAUSE SERIOUS ILLNESS, SUCH AS BRAIN DAMAGE, ESPECIALLY IN CHILDREN. PREGNANT WOMEN SHOULD ALSO AVOID EXPOSURE. Wear a NIOSH-approved respirator to control lead exposure. Clean up carefully with a HEPA vacuum and a wet mop. Before you start, find out how to protect yourself and your family by contacting the National Lead Information Hotline at 1-800-424-LEAD or log on to www.epa.gov/lead.
Verify the presence of lead-based paint, particularly in buildings constructed before 1978, and confirm that any required hazardous materials assessments have been completed. If lead is identified, presumed, or suspected, any renovation, repair, or painting activities that disturb lead-based paint must comply with the EPA Lead Renovation, Repair and Painting (RRP) Rule, applicable state laws, and required work practices to prevent lead contamination.
Under the RRP Rule, covered work in homes, child care facilities, and kindergartens built before 1978 must be performed by EPA- or statecertified firms using certified renovators and other trained workers as required. These requirements may also apply to in-house maintenance staff and many types of outside contractors. Certified renovators must complete training through an EPA-accredited training provider, and firms must obtain certification by submitting the required application and fee to EPA before performing covered work. Violations of the RRP Rule can result in substantial fines—often severe enough to threaten the financial stability of a company or even force it out of business.
Remove all surface contamination by washing with an appropriate cleaner, rinse thoroughly and allow to dry. Existing peeled or checked paint should be scraped and sanded to a sound surface. Glossy surfaces should be sanded dull. Stains from water, smoke, ink, pencil, grease, etc. should be sealed with the appropriate primer/sealer. Recognize that any surface preparation short of total removal of the old coating may compromise the service length of the system.
Remove loose, peeling, or chalky paint by sanding, scraping, or other appropriate methods. Abrade smooth or glossy coatings to promote adhesion. Apply a test area and allow the coating to cure before performing adhesion testing. If adhesion is inadequate, additional surface preparation or coating removal may be required. If coatings are severely deteriorated, remove to a sound substrate and treat as a new surface. Whether overcoating is feasible depends on the condition and compatibility of the existing coating system.
CAUTION: Do not mix bleach with ammonia or detergents. Wear protective eyewear, gloves, and protective clothing.
Surface preparation is not a one-size-fits-all process. While cleaning and allowing the substrate to dry are universal requirements, each substrate requires a focused approach based on its specific characteristics and condition. Even the best coatings, applied correctly, will not perform satisfactorily if surface preparation is overlooked or not performed properly. Due to variations in substrates, preparation methods, application techniques, and environmental conditions, test the complete coating system for adhesion and compatibility prior to full-scale application.
IMPORTANT: The primer recommendations provided here represent our preferred selections for optimal performance. Alternative primers may also be suitable, depending on the project’s performance requirements and budget.
