Big, nasty cleaning jobs—prepping a long-neglected exterior surface for paint, say, or purging years of grime discovered behind a kitchen appliance—call for a heavy-duty cleanser. Trisodium phosphate, commonly known as TSP, may be just the ticket to banish major messes, but this potent, inexpensive cleaning product does have its drawbacks.
Read on to learn the ABCs of TSP and how it should best be used to see if it’s the weapon of choice to defeat your toughest cleaning challenges.
What is Trisodium Phosphate?
An inorganic chemical compound (Na₃PO₄), TSP is a white granular or crystalline substance that can be mixed with water to create an alkaline solution. Once diluted, TSP is a highly effective cleanser, degreaser, and stain remover.
It’s also used to prepare painted surfaces for refinishing or repainting, due to its ability to de-gloss paint as well as free the surface of flaking, peeling areas. It’s sold in powder form, typically as 75 to 80 percent trisodium phosphate and 20 to 25 percent sodium carbonate. TSP should be stored in a secure, dry place (humid conditions can cause clumping).
What Risks are Associated with Trisodium Phosphate?
A toxic substance, TSP can be harmful if swallowed, and exposure to it (in granular or diluted form) can cause serious eye injury and skin irritation. Personal protection equipment (PPE), including long pants and sleeves, waterproof gloves, goggles, and a respirator, should be worn when preparing and using TSP (check out this Safety Data Sheet for more information).
Up until the late 20th century, trisodium phosphate was a common ingredient in household cleaners and detergents, but negative environmental impact led to strict limitations on its use. Phosphate runoff into lakes and rivers was found to trigger algae overgrowth, depleting oxygen in the water and endangering fish, animals, and aquatic plants.
Now TSP is no longer included in most commercial products, and its sale remains banned or restricted in various states and cities (consult your state’s environmental protection agency, health department, or department of natural resources’ water quality division for local laws).
TSP can damage some common surfaces in and around the home; particularly vulnerable are bathroom fixtures such as faucets, pipes, shower/tub enclosures, and drains. Its high alkalinity can etch glass, mirrors, and ceramic tile, as well as darken and corrode aluminum, chrome, and other metals. TSP eats away at grout and shouldn’t be used for general cleaning on painted wood.
Take care around foliage when using TSP outdoors. Opt for a windless day if possible, and hose down landscaping, before and after use, to avoid exposing and potentially damaging plants.
Where is TSP the Most Effective?
If you keep the caveats detailed above in mind, you may choose to employ TSP for various tough cleaning jobs.
- Power through accumulated layers of dirt, grease, grime, soot, and stains on exteriors—notably masonry (brick, stone, cement, and concrete), wood (decks and siding), and roofing.
- When prepping for a paint job, TSP can clean and de-gloss painted surfaces and remove peeling, flaking old paint.
- Inside the house, TSP works well on the stubborn sort of grease-meets-dirt gunk typically found after pulling an old stove or fridge away from the wall.
- Though it shouldn’t be used to clean grout, TSP can be used to remove it; TSP is an active ingredient in grout removal products.
- TSP can safely be mixed with bleach to remove mold and mildew (see below for measurement guidelines).
How Should TSP be Prepared and Applied?
Always read and follow package directions to the letter, heed all safety warnings, and don PPE when mixing and using TSP. As a rule, use the least amount of TSP that will be effective for your purposes.
Consider this general formula:
- Dissolve half a cup of TSP in two gallons of warm water, resulting in a slightly cloudy, odorless solution.
- To combat mold and mildew, a stronger batch of one cup of TSP to three quarts of warm water, plus a quart of chlorine bleach, may be used
- The solution can be funneled into a spray bottle or applied from the mixing bucket with a stiff scrub brush or sponge. Apply in broad strokes with some elbow grease. Rinse thoroughly with plain water to banish any TSP residue.
Are There Alternatives to TSP?
An erroneously named phosphate-free version of TSP exists, which relies on sodium sesquicarbonate as its main ingredient. Sodium borate, aka borax, is another heavy-duty cleaner that can tackle tough jobs. But without phosphate, they will likely be less effective at getting rid of grease.