Painting - Surface Preparation

Coating integrity and service life will be reduced because of improperly prepared surfaces. Up to 80% of all coatings failures can be directly attributed to inadequate surface preparation that affects coating adhesion. Selection and implementation of proper surface preparation ensures coating adhesion to the substrate and prolongs the service life of the coating system.

Selection of the proper method of surface preparation depends on:
the substrate, the environment, and the expected service life of the coating system. Economics, surface contamination, and the effect on the substrate will also influence the selection of surface preparation methods.

No exterior painting should be done immediately after a rain, during foggy weather, when rain is predicted, or when the temperature is below 10°C (50°F).

PREVIOUSLY PAINTED SURFACES:
Sound preparation is essential to good-looking, long-lasting results. A properly prepared surface should be clean, solid, dull, dry, and patched or caulked. Peeling or flaking paint must be removed by using a paint scraper, wire brush, sandpaper, or powerwasher. Remove any mildew present.

Surfaces that have not been previously painted or that are exposed down to the original surface should be handled as follows:

WOOD, WOOD COMPOSITION BOARD, OR HARDBOARD:
These surfaces must be primed with an exterior wood primer. After priming, caulk nail heads, holes, and siding joints, as well as around window and door frames. Prime bare plywood with a Latex Primer and let dry. Prime other woods with an Oil Primer.

CONCRETE BLOCK:
Allow new mortar to cure at least 30 days. If a smooth surface is desired, apply a Block Filler following label directions.

POURED CONCRETE, STUCCO/MASONRY, AND CEMENT COMPOSITION BOARD:
These surfaces must cure for at least 30 days and have no moisture problems. The surface should be primed with an Exterior Acrylic Masonry Primer.

CONCRETE FLOORS:
Remove grease using a degreasing cleaner. Then, etch (roughen) the floor by scrubbing with one part muriatic acid to three parts water. (Wear rubber gloves and protective clothing.) Rinse well with water and let dry for 48 to 72 hours. Cure 30 days. Before painting, perform a moisture test. Tape a 600 mm square of plastic to the floor and wait 48 hours. If concrete discolors or there is moisture on the underside of the plastic, don’t paint.

METAL:
Once clean and the rust has been removed using a wire brush and sandpaper, metal should be primed the same day it is cleaned with the appropriate an All-Surface Enamel Primer. Unfinished galvanized metal or aluminum should be wiped with degreasing cleaner, rinsed, and dried. No primer is needed if it will be topcoated with latex paint.

Brick
Brick must be free of dirt, loose and excess mortar, and foreign material.

All brick should be allowed to weather for at least one year followed by wire brushing to remove efflorescence.

Treat the bare brick with one coat of a masonry conditioner.

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