We need to clean and prepare the wall before painting it. Although there is no best way to clean walls before painting, most walls can be cleaned with sponges and warm water. For long-term oily or soiled surfaces ( such as kitchen walls ), use water and detergent solution for cleaning, and then use water to remove the residual detergent. Finally,  wipe the wall with a damp cloth. Applying primer or paint to the damp wall can cause a lot of problems, such as mildew and bubbles, etc.

Step 2 : Check the wall to solve the problem

No matter which space you are ready to paint, make sure to solve any problems on the wall first. Never paint on a problematic wall because it will produce new problem through new paints, which will make subsequent cleaning and maintenance more difficult.

In the discovery of wall problems in a timely manner to solve, such as the discovery of mold, check whether there is the seepage, water pipe rupture and other issues. If there is the simple air wetting,  the simple mildew will produce. It is recommended that you use sponge and three to four copies of water to a bleach solution to clean mold. Apply the solution, condense it for a few minutes, scrub the affected surface with a soft brush, and then rinse the area with water. If problems such as bubbles and cracking are found, remedial measures should be taken accordingly.