Should I Wash My Walls Before Painting?

Before repainting your room, it’s always a good idea to wash those walls first. Years of dust, nicotine, and airborne grunge can result in poor surface adhesion and a paint job that just won’t stick. To remove the gunk and rough up the surface for painting, it takes a little bit of elbow grease and the right products. One of the more popular and most effective wall prep cleansers that painters use is a product called Trisodium phosphate, known as TSP.

Materials needed:
Trisodium phosphate (TSP)
2 buckets
Green 3M Scotchbrite pad
Rubber gloves
Protective clothing
Protective tarp for floor.

Step 1: Mix 1/4 cup TSP with one gallon of water in one of the buckets. For extremely dirty or greasy walls, increase to 1/2 cup TSP. Fill a second bucket with plain, but warm water.

Step 2: Apply the TSP solution to the walls or ceiling using a sponge, squeezing out excess liquid to avoid drips. We’ve discovered it’s best to start at the bottom of the wall and work our way up to avoid streaking.

Step 3: Let the cleanser sit on the wall for a few minutes, then rinse off with warm water at least a couple of times to remove all the gunk and cleanser. A thorough rinsing is important, and not a step that should be overlooked, since residual phosphates can prevent that new paint from sticking.

Step 4: For especially stubborn stains or built up kitchen grease, use the Scotchbrite pad to scrub away at the buildup before rinsing.

Step 5: Let the walls dry thoroughly ~ 24 hours is recommended ~ before applying primer to your walls.

TSP is cheap and effective, and has the ability to slightly etch the surface of your painted walls to improve paint adhesion. It is strong however, and can burn your skin if exposed. TSP can also damage linoleum floors and woodwork which is why extra care must be used with this product.

If TSP is a much too caustic for your liking, an alternative product is something called Dirtex. This product comes in powdered form, requires no rinsing, and is safe on hands and skin. The instructions call for mixing it with water, applying, and allowing it to dry before applying primer. Like TSP, Dirtex has the ability to clean off the gunk and degloss walls, both which will improve paint adhesion.

Both Dirtex and TSP are available at your local hardware stores and Home Depot.

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