TSP - Trisodium Phosphate
The Painter's Degreasing Choice

The quality of a paint job depends on a perfectly clean surface. The surface may not need sanding and stripping, but it must be clean.

Using a powerful degreaser, like trisodium phosphate (TSP), to clean and etch the surface is strongly recommended. For the last several decades, professional painters have used this product to remove dirt, grease, mildew, and soap scum from both interior and exterior surfaces.

This chemical deglosses shiny surfaces, providing "tooth" so the next layer of paint can stick.
It can also be used to clean and soften hardened paint brushes.

Safety First - Handling TSP Correctly

TSP is a strong cleaner. It can cause irritation and even burns if it is used incorrectly. The following recommendations will reduce your risk of injury.

Wear rubber gloves, safety goggles, and long sleeves when working with trisodium phosphate.
Avoid letting the chemical touch bare skin or eyes.
If skin contact occurs, wash thoroughly with soap and water.
Discontinue use if redness, prolonged irritation, blistering, or pain occurs.
If eye contact occurs, flush with clean water for at least 15 minutes. Seek immediate medical attention.
If ingested, DO NOT induce vomiting. Drink a glass of water or milk. Seek immediate medical attention.

Protect Surfaces You Aren't Painting

It's also important to protect household surfaces from TSP splashes. Painted surfaces, finished wood, and metals can be discolored or de-glossed by TSP. Be sure to mask off anything you don't want to get damaged.

TSP Mixing Instructions

For most applications, a solution of 1/4 cup trisodium phosphate per gallon of very warm water is appropriate.

For very dirty or greasy surfaces (such as kitchen cabinets), increase the ratio to 1/2 cup TSP per gallon of water.

There are extra-strength or no-rinse formulas. If using one of these types of TSP, read the package directions. The proportions may be different from those given above.

Using the TSP to Prepare Paint Surfaces

Hand-Washing with TSP

To hand-wash the surface, use a sponge to apply the warm solution. Dip the sponge in the TSP solution. Wring it out until the sponge is damp.

Always wash the wall from the bottom up. It reduces streaking. Allow the solution to sit on the wall for two minutes to soften deposits, then scrub, also working from the bottom up.

Heavy buildup may require a nylon scrub pad. Avoid scrubbing the wall with anything that could damage the surface.

Rinse the surface thoroughly. Any residue could prevent the paint from adhering to the wall and waste your efforts to prepare the surface for painting.

Power Washing with TSP

Outside, TSP can be used to wash siding, fences, and masonry. Apply the TSP cleaning solution with a pressure washer or garden sprayer.

Standard TSP must be rinsed away with clean water. Depending on how dirty the surface is, several rinses may be necessary. As a general rule, if the water in the rinse bucket is dirty, it is worth your effort to rinse the wall again with clean water.

No-rinse TSP is fairly new invention. It isn't as strong as the original TSP, but it is well-suited for lightly soiled surfaces and general-purpose cleaning. It requires no rinsing when mixed as directed.