Surface Preparation Guide: Things to Do Before Painting
The performance of any paint job is dependent upon various factors including materials used for a paint job, suitable temperature, appropriate application and the paint itself. But, one factor that is the key to a long lasting paint job is “the correct and thorough preparation of the surface.” Even the most technologically advanced and the expensive coating system fail, if the surface preparation is incomplete or incorrect. It is no secret that painting is a one-time process, once failed you have to redo it entirely and that can cause you for both money and time. So, if you do not want to fall in such a situation, you must take care of the following surface preparation guidelines:
Step 1: Surface Contamination
In a study, it is found that the majority of paint and coating-related failure are directly attributed to improper surface preparation. This may include cleaning, surface roughening, chemical pretreatment and de-greasing. As we know, the performance of coating is highly dependent on the surface preparation and hence, all the surfaces to be coated must be completely clean, dry and free from dirt, grease, oil or any other atmospheric contamination. Also, make sure that surface acquires the specified cleanliness until the first coat is applied.
There are several basic methods and products for removing contaminants that depend on the surface you are going to coat. However, the very basic thing that you can use for cleaning any surface is soap and water. But, “Kuch Daag Aasani Se Nahi Jate” – some stains are not easily removable and for that sometimes you need a specialized product like organic solvents, emulsion degreasing agents, Trisodium phosphate (TSP) solution or Krud Kutter Pre-Paint Cleaner (TSP Substitute).
Step 2: Remove any Loose, Peeling Paint and Dents
Before painting or coating, it is important to make sure that the surface you are coating is free of all the imperfections. It may include mill marks, which are caused while manufacturing, dents, and gauges that usually introduced while handling. In addition to that, you also need to check any loose paint, loose rust or other imperfection in case you are planning to coat any old material surface.
If you find anything like above on the surface to be coated, it is recommended to sand it first using sanding paper, wire brush, steel wool, scraper, etc. Moreover, if you are thinking of coating any wooden surface, you also need to hammer down all the screws and nails in order to make the surface smooth for further sanding.
Surface cleaning by these specified hand tools such as sandpaper, wire brushes is enough for many surfaces. But at some point like mill scale and tough stain, these are not as much effective as the other power tools such as power wire brushes, needle guns, grinders, and sanders. However, care should be taken while using these tools, especially with power wire brushes.
Step 3: Rinse the Surface
After sanding, rinse with fresh water to remove any grime, dust, and dirt left on the surface. Now, let it dry completely before priming or top coating.
Step 4: Environment Conditions
Even if surface preparation is carried out appropriately, improper environmental circumstances might affect the paint results. So, it is recommended to check environmental conditions before painting or top coating. Almost all the top coat and paint products contain instruction guide for their application and suitable environment circumstances that you can follow to complete your paint job effectively.
Step 4: Priming
Priming is an essential step in preparing the surface for paint, especially if you are painting a surface that is highly exposed to moisture. It ensures excellent adhesion of paint/top coat on the surface and caters better protection to the surface being painted. So, before to start painting, a suitable coat of primer is required to achieve the desired results. Also, priming provides a thicker film buildup, which helps in creating a flat and smooth surface that ultimately increases the durability of the paint to be applied. Below mentioned are the surfaces that need priming:
Bare Metal: Priming is ideal for painting the bare metal as it creates the strong foundation needed to bond with the paint for last-longer. Also, it adds rust-inhibitive function for your coating.
Bare Wood: The objective of priming bare wood is not just limited to provide an opaque best coat, although it has various important functions as well. Since bare wood is porous by nature that means it contains many tiny holes and openings, which requires additional treatment to seal the surface. This is why, the bare wood is recommended to be primed before painting, as primer comes with a high solid content that can easily fill the grain in the wood and can make the finish coat smoother.
Concrete: Whether you are thinking of painting an indoor or outdoor surface, priming is an essential step in top coating concrete surface. There is a range of primer options such as Acrylic Primer, Polyurethane Primer, Epoxy Primer, etc. that can be used on the concrete surface accordingly.
Darkly Painted Surface: If you are changing a dark coat into a light coat, a primer is an absolute must in order to cover your old color completely. Also, it helps in preventing bleeding of your old color through your new top coat.
Step 5: Top Coat the surface
Once the primer has dried, it’s time to apply paint on the surface. There are a huge number of paints along with numerous color options (for both Aerosol and Brush) are available in the market that you can use to provide desired coat on the surface. But, the application of all paints are same that mentioned in the below section, take a look!!
Aerosol Paint Application: If you are planning to work with aerosol spray paint, it is recommended to do it in a well-ventilated area. It provides better coating as well as saves you from sudden injuries. Also, wear gloves and a mask while using aerosol spray paint, especially if you’re spraying in a confined space like a garage. Follow the manufacturer's instructions that mentioned on the side of the cane for best results. Spray in short smooth strokes or even coats, holding the can about 10 inches from the surface. Keep your spray cane parallel and about 10-16” away from the surface to be painted and spray in a steady back and forth motion.
Brush Paint Application: The key to a good paint job is to use a high-quality paint and a good paint brush or roller and apply a liberal coat to the entire surface of the dresser, avoiding excessive brushing. Next, stir the paint thoroughly. For best control, hold your brush at the base of your handle (the end closest to the bristles).
Step 6: Re-Coat the Surface, if Necessary
Follow recoating directions mentioned on your cane. Apply a second coat of paint if necessary. Each application dries to touch at a different rate, so let your painted surface dry for the specified time.