Latex- and oil-based house paints are formulated to withstand wear and exposure to severe weather conditions. Many manufacturers offer specific formulations for regional climates.
Surface preparation is critically important for good adhesion. Proper preparation includes scraping as much old paint as possible from the surface, sanding to feather edges of scraped areas, washing the surface with a good detergent solution, repairing chips, cracks, splinters, etc., cleaning and sealing nail heads.
Major problems encountered with house paints are generally due to:
- Failure to completely clean surface of dirt, grease, old paint, etc.
- Excessive moisture
- Painting damp surfaces
- Painting under adverse weather conditions
- Failure to use proper primer coat
- Failure to follow manufacturer’s directions
Any of these conditions can cause blistering, peeling, early fading or other similar problems.
Trim paints are bright colors, chosen to contrast with the house color. They dry quickly to a hard finish; they are primarily for use on window frames, shutters, railings, etc. and are not recommended for large surfaces.
Masonry surfaces include stucco, concrete, cement, asbestos shingles, etc. Most masonry paints are latex based; some are acrylic based. Oil-based paint is not recommended for masonry because of the residual alkalinity in the masonry.
Latex-based masonry paints require a special pretreatment or bonding primer to ‘tie down’ old chalk and dust before application. They dry to a flat finish.
Rough surfaces should first receive a coat of block filler. Acrylic elastomeric coatings bridge cracks and pinholes to provide the best waterproofing.
Powdered cement paints, which have a shorter exterior life than latex coatings, must be mixed with water. They can be applied only over a porous masonry surface such as brick, stucco or concrete, or over surfaces that have been previously coated with this same kind of paint. For proper adhesion, the old surface must be wetted down thoroughly and the paint applied to the damp surface.
Masonry paint can be waterproof as well as decorative. For best color retention, coat with a good acrylic-latex paint 30 days after application of a waterproof masonry paint.
Paint for Gutters
Both latex- and oil-based paints adhere well to galvanized steel and aluminum gutters. Oil based works better on tin gutters.
Galvanized gutters require priming both inside and out and should be cleaned with coarse cloth dampened with paint thinner before they are painted, or should be left unpainted for three to six months so the weather can etch the surface for better paint adhesion.
Oil-based paints should never be applied directly to unpainted galvanized metal. They will eventually peel off. A galvanized metal primer must be applied first. Acrylic-latex paint can be applied directly to unpainted galvanized as long as it has been cleaned thoroughly.
Many shingle paints (really stains) are low in pigment content, leave light color on the surface, and are used primarily to provide surface protection for wood shingles.
In some instances, shingle paints may be applied without a primer. Where the surface is badly weathered, recommendations may call for a companion primer, undercoater or two finish coats.
Most shingle paints have oil or alkyd-resin base, which thins with turpentine or similar solvent.
For home improvement advice, visit JS West Lumber & Ace Hardware Sonora, Ca. or visit www.acehardware.com and click on the Answers@Ace icon. Answers@Ace is an online resource with information for do-it-yourselfers about hardware and home improvement projects. The Everyday Projects section has pictures and detailed, step-by-step instructions for this and many more home improvement projects.
To speak to an Ace Hardware advisor in Sonora call: 209 532 7446.