Sodium percarbonate is a white powder that dissolves in water to release hydrogen peroxide (the active cleaning and bleaching agent) and soda ash (a water softener). That two-in-one reaction makes it one of the most versatile oxygen-based cleaners you can buy. You can use it for laundry, deck cleaning, grout scrubbing, and sanitizing brewing equipment, all with slightly different mixing ratios and techniques.
How It Works in Water
When sodium percarbonate hits water, it splits into sodium carbonate and hydrogen peroxide. The hydrogen peroxide then breaks down further into water and oxygen. That burst of oxygen is what lifts stains, whitens fabric, and kills mold and mildew. The sodium carbonate left behind raises the pH of the solution, which boosts cleaning power on greasy or organic soils.
Temperature matters more than almost any other variable. Research on cotton bleaching found that water temperature had the single biggest influence on cleaning performance, ahead of both concentration and soak time. Warm to hot water (around 50 to 70°C, or 120 to 160°F) dissolves the powder fully and accelerates oxygen release. Cold water works poorly. If you’re filling a bucket or a washing machine, use the hottest water the surface or fabric can handle, then let the powder dissolve before adding items.
Laundry
For a standard washing machine load, add half a cup of sodium percarbonate along with your regular detergent. Add the powder while the machine is filling so it dissolves before the clothes go in. If you’re using a highly concentrated grade (some products are sold this way), cut the amount to roughly one-eighth of a cup per load. Check the label if you’re unsure which grade you have.
For heavily stained whites or dingy towels, you can presoak items in a basin with two tablespoons of sodium percarbonate per gallon of hot water for 30 minutes to several hours before washing normally. This is especially useful for removing yellowing from cotton sheets, brightening cloth diapers, or pulling out food stains.
Fabrics to Avoid
Sodium percarbonate is safe for cotton, linen, polyester, and most synthetic blends. Wool is a different story. Research using infrared spectroscopy to measure fiber damage found that sodium percarbonate caused slight but measurable structural changes to wool fabric. It’s gentler than chlorine bleach (which severely damaged wool in the same study), but hydrogen peroxide alone was the only bleaching agent that left wool essentially undamaged. Avoid using sodium percarbonate on wool, silk, or any other protein-based fiber. Don’t use it on materials that are labeled “no bleach” either.
Cleaning Decks, Siding, and Concrete
For outdoor surfaces, mix 4 ounces (roughly half a cup) of sodium percarbonate into one gallon of warm or hot water. Stir until dissolved. You can scale this ratio down to about 1 ounce per quart for smaller jobs.
Apply the solution with a pump-style garden sprayer, or pour it from a bucket and spread it with a stiff broom or brush. Let it sit on the surface for 10 to 30 minutes. You’ll often see the solution fizzing gently as it works on grime, algae, or weathered gray wood fibers. Scrub stubborn areas with a deck brush, then rinse thoroughly with a garden hose or pressure washer on a low setting.
This works well on wood decking, wood fencing, vinyl siding, stucco, and concrete patios. For concrete driveways with oil stains, sodium percarbonate alone may not be enough since it targets organic soils best. On wood, it brightens without the fiber damage that chlorine bleach causes, making it a popular choice before re-staining a deck.
Grout, Tile, and Hard Indoor Surfaces
Use the same basic ratio of 1 ounce per quart of hot water for indoor hard surfaces. For tile grout, pour or sponge the solution onto the grout lines, let it sit for 15 to 30 minutes, then scrub with a stiff brush and rinse. The oxygen release helps lift mildew and soap scum that has settled into porous grout.
For tougher buildup, you can make a thicker paste by mixing a few tablespoons of sodium percarbonate with just enough warm water to form a spreadable consistency. Apply the paste directly to stained grout or caulk seams, let it dwell for 20 to 30 minutes, scrub, and rinse. This concentrated contact works well in showers and around bathtub edges where mildew tends to build up.
Sodium percarbonate also cleans stained coffee mugs, discolored plastic containers, and baked-on residue inside ovens (applied as a paste, left to sit, then wiped clean). For any enclosed container, leave the lid off while the solution works. The oxygen gas it releases can build pressure in sealed vessels.
Sanitizing Brewing and Food Equipment
Homebrewers frequently use sodium percarbonate-based cleaners to remove organic residue from fermenters, bottles, and tubing. The standard approach is 1 tablespoon per gallon of water for general cleaning, or up to 2 ounces per gallon for heavy soils like dried yeast cake or protein buildup. Soak equipment for 30 minutes, then rinse thoroughly. Sodium percarbonate is a cleaner, not a no-rinse sanitizer, so you’ll still need a separate sanitizing step before brewing.
One important compatibility note: do not use sodium percarbonate on aluminum equipment. The alkaline solution reacts with aluminum and can pit or corrode the surface. Stainless steel, glass, and food-grade plastic are all fine.
Storage and Safety
Sodium percarbonate is classified as an oxidizer. In practical terms, that means it can accelerate combustion if it contacts flammable materials. Store it in its original container or a sealed plastic tub, away from heat sources and away from oils, paper, or rags. Never mix it with vinegar, acids, or ammonia-based cleaners. Combining it with acids neutralizes the cleaning reaction at best and can release irritating gases at worst.
Keep the powder completely dry during storage. Any moisture will trigger the decomposition reaction inside the container, slowly degrading the product and potentially building gas pressure in a sealed bag. A cool, dry shelf in a garage or laundry room works well.
When handling the dry powder, wear gloves and avoid inhaling the dust. It can irritate skin, eyes, and mucous membranes on contact. If you’re mixing a large batch in an enclosed space, open a window. Once dissolved in water at household cleaning concentrations, the solution is much milder, comparable to a dilute hydrogen peroxide solution, but you should still wear gloves for prolonged scrubbing sessions.
Quick-Reference Mixing Ratios
- Laundry (standard grade): 1/2 cup per full machine load, added during fill
- Presoak for stains: 2 tablespoons per gallon of hot water, 30 minutes to overnight
- Decks, siding, concrete: 4 ounces (1/2 cup) per gallon of warm water, 10 to 30 minute dwell time
- Grout and tile: 1 ounce per quart of hot water, or a thick paste for stubborn stains
- Brewing equipment: 1 tablespoon per gallon for general cleaning, 2 ounces per gallon for heavy soils, 30 minute soak
In every case, hotter water activates the powder faster and more completely. Dissolve the powder before submerging items or applying to surfaces. And always rinse well after cleaning, since the alkaline residue left behind can feel slippery on surfaces and may dull certain finishes if left to dry.