Typically, early paint failure occurs when people rush the preparation process. Since improper painting preparation can adversely affect the anticipated service life of a coating system, it pays to know as much as possible about surface preparation before you start painting.
Painting Preparation by Substrate Type
The main objective of surface preparation is to ensure good coating adhesion. Keep reading the rest of this post to to find out how to prepare different types of surfaces for painting.
Before painting over brick, it’s important to clean the surface thoroughly. For this, you should:
- use a brush and a mild detergent solution to remove efflorescence (a crystalline deposit on surfaces) and dirt;
- apply a TSP-bleach solution to eliminate persistent stains and mold;
- rinse and wait at least 24 hours for the surface to dry;
- inspect the mortar for signs of damage, make the necessary repairs, and let the surface dry completely;
- apply the paint; don’t paint over newly installed brick, as the clay minerals may rise to the surface, compromising your paint job.
Stucco must provide a sound substrate to ensure the good looks and longevity of a paint job. Painting preparation for stucco involves:
- pressure washing the exterior to remove dust, chalk, stains, and mildew;
- using the right product to repair cracks and holes (e.g. brushable elastomeric sealants or polyurethane caulks/sealants);
- applying a surface conditioner to areas that are sandy, crumbly, or chalky;
- checking the pH level; according to professional painters, paint should be applied only if the pH level is between 7 and 9.
When preparing plaster for painting, it’s imperative to:
- let fresh plaster cure and dry for at least 30 days;
- repair cracks and patch low points with a high-quality joint compound if you’re planning on painting over old plaster; also, replace the areas that are crumbling with new plaster;
- sand the surface smooth and remove the sanding dust;
- apply a high-quality primer compatible with the chosen paint system.
For proper drywall painting preparation, you need to:
- make all the necessary repairs, including filling cracks and fixing holes;
- sand the walls properly with 120- or 150-grit sandpaper to achieve a smooth finish; avoid oversanding, as it may damage the surface;
- wipe down all surfaces with a slightly damp cloth to remove the dust;
- prime your walls and let them dry optimally before applying the paint.
While new wood siding and trim require very little preparation, previously painted wood surfaces should be:
- washed with a TSP solution according to label directions and rinsed off thoroughly; for persistent stains, you can use a special solution;
- sanded with fine-grit sandpaper to smooth away imperfections and wiped with a damp cloth to remove the sanding dust;
- primed with a high-quality wood primer.
Vinyl and Aluminum Siding
According to experts, vinyl and aluminum siding painting preparation implies:
- cleaning the surface with a mild detergent solution or with a mixture of one part bleach to four parts water;
- rinsing the siding thoroughly and allowing it to dry completely;
- reattaching loose pieces of siding, repairing cracks between the siding and other surfaces, and filling holes and dents in aluminum with exterior-grade spackling paste;
- priming the surface for optimum paint adhesion.
To ensure the success of your project, try to identify and solve underlying problems, such as water ingress, mold growth, decayed wood, and pest infestation, before painting. For more information about the method and level of painting preparation required for your project, contact our professional painters at (904) 641-4800.