OSB, i.e. oriented strand board, is characterized by a rough texture and irregular appearance. It is a solid and popular choice as an underlay for carpet, tiles, wooden floors, wall coverings and roofs. OSB is composed of many layers of shredded, lower quality wood. This board is primarily intended to be used as a functional material, not as a finishing material. Painting OSB boards is a quick step in interior finishing.
It is widely accepted in the construction industry due to its low cost, high durability and availability. If you want to use OSB as a finishing material, you can paint it to make it look good and perhaps improve its usability. However, OSB has several limitations and requires special preparation before painting.
Painting OSB boards – preparation
OSB has a thin layer of wax that protects it from moisture and makes it difficult to paint. Additionally, the OSB structure will likely be visible after one coat of paint, so it is necessary to use filler and a thick primer to remove some of the wood structure. You should also avoid exposing the OSB edges to water, as this may cause the board to swell or crack. OSB can withstand certain periods of rain or exposure to weather conditions. However, OSB manufacturers do not recommend long-term exposure to external conditions. If construction is delayed long enough, water eventually seeps through the material and causes it to swell and fall apart. Edges cut in place are particularly susceptible to moisture penetration. Factory edges handle water better because they are finished with a sealant during production.
Before starting work
There are a few steps you need to take before painting. If you want to smooth out the texture so that criss-crossing wood chips are not visible, you can add a polyester resin filler and then alternate layers of filler and sanding to smooth out the board’s texture. Check with the manufacturer to see if the OSB has a thin wax coating to protect it from moisture. If so, it must be removed with a wooden floor wax remover before painting. Some OSB boards appear to have a surface layer of wax, a result of the high pressure placed on the material by the manufacturing machinery. Once the board is ready, apply a generous amount of primer. Open OSB structures absorb paint, requiring two or three coats of primer to close these pores.
- Light Surface Sanding: Before painting, sand the OSB surface using 80 grit sandpaper on an oscillating sander. Lightly sand the surface, but do not sand the edges.
- Thorough Surface Cleaning: Due to the rough texture of OSB, adhesive cloths and cotton cloths do not work very well. Instead, clean the surface with an industrial vacuum cleaner with a brush attachment.
- Several Layers of Primer: Wear gloves. Pour the foundation into the container. Dip the roller in the foundation and roll it evenly over the container. Apply the primer to the OSB using “W”-shaped movements. Don’t apply it too thickly