How to Prepare Surfaces Before Painting
Painting involves more than simply opening a can of paint and applying it directly to walls; surface preparation is crucial to ensuring your finish remains flawless for as long as possible and looks spectacular.
If your surfaces are dirty or poorly prepared, even top-rated paint will appear unattractive and peel or crack after application. To ensure that your painting job looks its best, follow these steps:
Surface Preparation
Surface preparation refers to the first-stage treatment of substrate material prior to applying coatings, linings or paint. It is the cornerstone of any successful corrosion protection system.
Hiring quality commercial painting contractors ensures your surfaces will be clear of dirt, grime and rust buildup that could prevent new paint from adhering properly. They will also repair metal burrs or holes so the new coat of paint adheres more fully.
Blasting is another effective method to prepare surfaces for painting. This involves using air pressure combined with special abrasive grains or materials to blast away mill scale and other contaminants while creating an appropriate profile for new coatings.
SSPC-SP2 is often specified as the standard surface preparation method for hot-dip galvanized steel. ASTM D6386 and D7803 list this surface preparation method as an acceptable way of smoothing new or partially weathered galvanized coatings and eliminating zinc high spots to enable repair with zinc rich paints.
Sanding
Painting over dirty surfaces will not only make adhesion difficult, but may lead to marks showing through after the first coat has dried – which may require additional coats of paint in order to cover. Thorough cleaning surfaces, sanding them down, and applying stain-blocking primer will be essential to getting optimal results.
As previously stated, top contractors dedicate considerable effort and time in this phase of the process. They understand that quality depends heavily on preparation steps taken correctly, thus making following them essential part of their job.
Patching
When painting large surfaces, the best approach is always starting on a clean, solid and dry base to ensure maximum longevity for any paint protective system.
If you discover an area requiring attention, use a putty knife to fill nail holes and small cracks in wood, plaster and drywall surfaces. For deeper or larger holes or cracks, first attempt sanding down and clearing away sanding dust before applying a thin skin of spackle and then sanding smooth after drying with damp cloth before spot-priming the area.
When applying chalk paint, be sure to match its texture to that of its surrounding areas in order to help any touched-up areas blend seamlessly into their surroundings. After completion of touch-up work, let it dry according to manufacturer recommendations before checking from various angles whether or not the touched up areas match up with those around them; if not, continue the process until they do.
Cleaning
No matter if it be wood or metal, even high quality paints can only do their work if prepared surfaces have been thoroughly prepared beforehand. A good painting contractor should take care to even out surfaces, repair blemishes, sand down any rough patches and prime the entire surface before even applying one brushstroke of paint.
Most walls require only warm, soapy water for cleaning; however, those caked in grease or stained with oil may require solvent-based cleaning with organic solvents such as TSP (trisodium phosphate). TSP is especially effective at breaking down oils, greases and grime from surfaces.
When painting metal surfaces, it must be free from all rust or corrosion to ensure proper adhesion and to prevent flash rusting. Rusting will continue to corrode the surface over time and eventually cause the new coating to peel away.
