Further adding to the confusion is the fact that paint manufacturers themselves don’t agree on just what kind of cleaning is essential. However, in general, warm, soapy water is typically the best approach. Fill up a bucket and gently scrub the wall with a sponge; start from the base and work your way up. You’ll eliminate most of the dust and grime, resulting in a surface that’s much smoother for applying paint. Read on for more tips and tricks on how to clean walls before painting.
Recommendations of Major Manufacturers
The major paint manufacturers have different recommendations on the necessity of cleaning interior wall before painting, ranging from a cursory wiping to firm scrubbing with mild chemicals. Consider the advice of the major paint companies:
PPG: “Wipe walls clean of dust and dirt.” Behr: “If you need to remove any oil, grease, or wax stains, apply a mild detergent with a sponge onto a lightly water-dampened surface, rinse with clean water and allow it to dry.” Benjamin Moore: “Most walls can be washed using a sponge and warm water. For surfaces that have exposure to oil or grime, like kitchen walls, wash with a solution of water and grease-cutting detergent and follow up with clean water to remove any residual cleaning agent. Finish by wiping the walls with a damp cloth.” Sherwin Williams: “Washing your walls and trim will remove grime, cobwebs, dust, and stains that can prevent your paint from adhering. Use a mixture of lukewarm water and mild soap, gently rubbing in a circular motion. Rinse your walls using a slightly damp cellulose sponge. Valspar: “Use an ordinary sponge mop to clean your ceiling and walls thoroughly with TSP and water. Rinse well and let dry. Moving from top to bottom, clean walls and moldings with sponges or rags.”
The reality, though, is that many people skip this step, or clean in a more cursory way. Not even pro painters are diligent about cleaning walls before they paint.
Professional Painters Usually Don’t Wash Walls
Professional painters hate washing walls. There are many good reasons for this. For one reason, they’re not in the business of washing—they’re in the business of painting. Washing cuts into painting time, which cuts into their income, so don’t expect your hired painter to wash down your walls unless you agree to pay them more for the service. Better yet, hire a cleaner to do this work, or do the cleaning yourself before the painter arrives. Instead, your hired painter is likely to pole-sand the flat surfaces with a fine-grit sandpaper. Light sanding sloughs off sticky dirt and junk, deglosses surfaces, and knocks down some of the stipple.
When You Might Be Able to Skip Washing
If you are painting the walls yourself and want to omit the step of washing walls as part of the preparation, the surfaces should meet at least most of the following conditions:
No excessive dust presentNo crayon or grease stains present on the wallsNo wood-burning fireplace in the houseWalls have little or no contact with handsNo pets in the houseNo cooking or bathing takes place in the room (meaning kitchens and bathrooms should always be washed before painting).Vertical surfaces only (trim work and ledges should always be washed)
The spaces that might qualify as rooms that don’t require active washing with detergent or TSP include:
Living room that does not get a lot of activity and was painted recently Primary bedroom used by adults, not children Dining room dedicated to dining only, rather than cooking A home office A family room that is well-treated with no wood-burning fireplace Powder room used only for toilet activities and hand-washing
Even these rooms, no matter how pristine, will require a wipe-down to eliminate loose dust.
When to Wash With Soap and Water
As noted above, most paint manufacturers recommend that you clean walls with at least mild detergent and water before painting. Although modern paints are so good that they bond well to almost any surface, it will adhere best to surfaces that are perfectly clean and smooth.
How to Wash Walls With Soap and Water
Walls that are visibly dusty or dirty from handprints or other grime should be washed with detergent and water. A good cleaning routine for walls looks like this:
When to Scrub with TSP
TSP (trisodium phosphate) is an inorganic powder (chemical formula Na3PO4) that creates an alkaline cleaning solution when mixed with water. The alkalinity makes it excellent at dissolving greases and oils, and TSP is recommended as a cleaning solution under certain conditions:
In kitchen areas that have accumulated grease In bathroom areas that have soap scum, or in bathrooms that get a lot of misted sprays, such as hairspray In areas that receive a lot of skin contact (near door handles, door jambs, etc.) In rooms with unusual amounts of nonwater-soluble markings (for instance, crayons in a kid’s room) On the walls, above heating registers
TSP also lightly etches surfaces, which makes it good for slightly dulling high-gloss paint surfaces. If the previous paint is a glossy finish, TSP washing can take the place of sanding to help the new paint bond. When washing with TSP, mix the powder with water as directed by the product label, then wash the walls with a sponge dampened in the solution. Work in sections about 3 feet square. Let the solution sit for about two minutes on each section, then scrub again with TSP. Immediately rinse each section with another sponge dampened in clean water. TSP can sometimes stain wood floors, so protect them with drop cloths. Also, keep the TSP off any surfaces that won’t be painted. It is mildly caustic and may etch painted or stained woodwork. Wearing rubber gloves is recommended.
