Exterior Preparation

As with interior painting, proper surface preparation is crucial for achieving a long lasting paint job. A thorough cleaning to remove dirt and mildew is the first step in preparing exterior surfaces.

All loose paint and defective caulking should then be removed. Any rotted boards should be replaced, and all new and bare wood primed. Gaps between adjoining wood, or wood and masonry, should be caulked with an elastomeric sealant. Hardware and light fixtures which are not to be painted should be removed or properly protected, and all plants should be moved or covered.

Rusty surfaces, such as steel lintels and wrought iron, may require special preparation. All loose rust should be removed, and the surface then primed with a rust inhibiting primer.

As with interior paints, many manufacturers have developed new latex products which offer superior performance over oil base paints. A 100% acrylic latex paint should be used for exterior surfaces. Less expensive paints generally contain a vinyl, or vinyl-acrylic, resin, which is not as durable as a 100% acrylic resin and does not retain

Generally, paints offered for residential use are either alkyd base (oil) or water base (latex). The base indicates the solvent used to suspend pigments (coloring agents) and resins (binding agents).

Because they dry slowly, alkyd paints should not be used for exterior painting in warm, humid climates. The slow drying time gives mold spores more opportunity to attach to the drying paint film.

This, combined with the nature of the resins in alkyd paints, provides a near perfect environment for mildew. Latex paints are much more mildew resistant. While most high-quality paints now contain mildewcides, such additives will only inhibit mildew growth, not prevent its occurrence.

No paint job will last forever. However, the life of paint can be extended with the proper care and maintenance. Interior paint is generally not subjected to conditions as harsh as exterior paint. Maintenance usually consists of little more than occasionally cleaning to remove dirt, grease, or fingerprints. Scuff marks, scratches, and chips require touch up.

Exterior paint requires considerably more maintenance. Regularly removing dirt and mildew will not only keep the paint looking fresh, but will also prevent mildew growth from destroying the paint film. In addition, an inspection for rotted wood and cracked caulk should be conducted at least once a year.

Promptly replacing rotted boards and repairing cracked caulk will prevent more extensive and expensive damage.

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