Surface preparation is an important factor in painting walls or any surface. Walls being painted for the first time will be prepared with a suitable primer, which works well if the surfaces are sufficiently clean. Walls being repainted must be cleaned to remove years worth of accumulated grime, grease and oil.
Paint will not bond very well to a wall if there is any grime, grease or contamination. Even oil from human skin contacts can cause issues. Painting under these circumstances will result in blistering, paint that peels away, discolouration or just an uneven looking paint job.
It is standard practice to clean walls with sugar soap or Trisodium Phosphate. These are mildly alkaline (base) solutions that remove most grease and oil from the surface of walls. Often this is sufficient preparation for re-painting walls.
Walls near cooking surfaces or fireplaces often need very heavy duty cleaning to remove grease or other contaminants from the walls. Bathrooms, which have soap scum in the atmosphere, and children’s rooms with crayons marks and hand prints may also require thorough cleaning.
- Citrus cleaners like De-Solv-It are very effective for cleaning sticky spaces and removing grease. This is inexpensive and available at hardware stores. It is also quite safe.
- Hand sanitizer will remove many visible wall marks. This is readily in most homes and worth trying
- Acetone is a very strong solvent, and quite volatile, but it will work for very stubborn grease. It should only be used in a ventilated area. (It is the basis for nail polish remover).
- Turpentine is the solvent in many non-water based paints. It will remove many grease stains. It is rather strong smelling and flammable, so use in a ventilated area.
Sections for doors, doorframes and windowsills that receive a lot of human contact will tend to accumulate a lot of skin oil, which prevents paint form bonding well. They may need to be cleaned with strong solvents.