Housekeeping House Cleaning Cleaning Tips What Is TSP Cleaner? Plus How to Use It Trisodium Phosphate (TSP) is a powerful cleaning agent, but its use is not without drawbacks. By Jolie Kerr Jolie Kerr Jolie Kerr is a cleaning expert and the author of the New York Times bestselling book, My Boyfriend Barfed In My Handbag ... And Other Things You Can't Ask Martha. Her work has appeared in GQ, Cosmopolitan, The New York Times and Town & Country. A graduate of Barnard College, Jolie lives in a tiny Manhattan apartment with her five vacuum cleaners. Learn about BHG's Editorial Process Published on October 6, 2023 Trending Videos Close this video player Photo: Getty Images / Natalia Kopyltsova Project Overview Total Time: 1 hour Skill Level: Intermediate Estimated Cost: $10 Trisodium phosphate (TSP) is an inexpensive and powerful cleaning agent that cuts through stubborn grime, mold, soot, and grease, eliminating stains. It is frequently used to prepare surfaces for repainting or refinishing. It is also a heavy-duty cleaner often used for home improvement projects like cleaning soot from a chimney or eliminating mold and mildew buildup on wooden decks or siding. While TSP is a versatile and effective heavy-duty cleaner, it is not without significant drawbacks. It is banned in many states, and its use is highly regulated in others because of its significant environmental impact on waterways. It is also highly caustic and can cause severe eye and skin damage if used improperly. This guide will explain the ways in which TSP should—and should not—be used for home improvement projects, as well as detailing the necessary safety precautions to take when working with TSP. What Is TSP? Trisodium phosphate, commonly known as TSP, is an inorganic chemical compound that is diluted with water to make a heavy-duty alkaline cleaning agent that can be used as a degreaser, stain remover, and to treat painted surfaces prior to repainting or refinishing. TSP is a white granular substance consisting of 75 to 80% trisodium phosphate and 20 to 25% sodium carbonate; its chemical formula is Na3PO4. TSP was widely used in consumer products in the 20th century, and it was especially prevalent as an ingredient in cleaning agents. It began to fall out of favor in the 1960s, as it became clear that phosphate-based products are associated with ecological damage to lakes and rivers. TSP is banned in many states, and its use is highly regulated in states where its sale is legal. However, TSP is still commonly used by contractors and painters to prepare surfaces for painting. Uses for TSP TSP is most often used to prepare painted surfaces before repainting or refinishing them, de-glossing existing paint and removing any paint that has flaked or peeled, leaving the surface clean and ready to accept new paint or finish. TSP is also used as a heavy-duty cleaning agent to remove layers of dirt, soot, grime, stains, and grease from exteriors, including masonry materials like brick, stone, concrete, cement, wood siding and decks, and roofing. It can also be used to clean long-neglected interior surfaces, such as dirty, greasy stretches of wall after removing large household appliances like refrigerators or ovens. When mixed with chlorine bleach, TSP is a powerful agent for mold and mildew elimination. TSP can be used to remove grout and is often found as an active ingredient in grout removal products because of its ability to dissolve grout. What to Avoid Cleaning with TSP When mixed with water, TSP is a highly alkaline solution that can cause irreversible damage to many common household surfaces. It is strongly recommended that TSP not be used in bathrooms, in particular, because it can darken and corrode metal fixtures; cause etching in glass and ceramic tile; and eat away at grout. The following materials and items should not be exposed to TSP: Aluminum, chrome, and other metalsFaucets, shower and tub enclosures, drains, and pipesGlass, including mirrorsCeramic tileGroutPainted or finished wood, including hardwood flooring, that is not intended to be strippedFoliage, plants, grass, and other landscaping elements Safety Precautions When Using TSP TSP is a strong base that can burn skin and cause severe eye damage; therefore, it is imperative to wear personal protective equipment (PPE) when working with it. As a highly regulated substance, it is also critical to read and follow package directions to the letter, including and especially the provided safety warnings. When working with TSP, wear suitable clothing, including long sleeves, waterproof work gloves, and eye protection. If there is foliage or landscaping present in the area where you will be using TSP, soak it with clean water before starting the job, and rinse it well after work has concluded to ensure that no TSP residue remains. Store TSP in a secure, dry area. What You'll Need Equipment / Tools 2 Sponge Bucket Materials PPE, including eye protection and waterproof work gloves TSP Hot water Instructions How to Use TSP for Cleaning Don PPE and Prepare Work Area Before mixing a TSP solution for cleaning, it is imperative that you don protective gear and prepare the work area to prevent damage. When mixing and working with TSP, wear eye protection, long sleeves, and waterproof work gloves. Plastic sheeting should be used to cover any areas that are not being cleaned with TSP. Mix TSP Solution When working with TSP, always read the package directions regarding dilution ratio, mixing instructions, and safety precautions, and follow those to the letter. A standard dilution ratio is 1/2 cup of TSP to 2 gallons of hot water; hot water is needed to ensure the TSP becomes soluble and dissolves. Once mixed, the TSP solution will appear slightly cloudy. The use of TSP to eliminate mold and mildew calls for a stronger solution that includes chlorine bleach. Typically that ratio is 1 cup of TSP to 3 quarts of hot water to 1 quart of chlorine bleach. Saturate and Wring Sponge Soak the sponge by holding it in the TSP solution and squeezing it several times. Then, holding the sponge over the bucket, squeeze the sponge again to extrude TSP solution until the sponge is just-damp. Avoid cleaning surfaces with a dripping wet sponge, which can leave white powdery streaks or spots as the solution dries. Clean the Surface from the Bottom Up Clean the surface, starting from the bottom and using a sweeping motion to work upward. Soak and wring the sponge in the TSP solution frequently while working. Rinse Surface As the TSP solution dries, it can leave a white powdery residue on the surface that has been cleaned, which needs to be rinsed away. Using a new sponge and a clean bucket filled with cool water, wipe the surface clean.