Welcome to a deep dive into sodium percarbonate.
What it is
Sodium percarbonate is a white crystalline powder made by combining two things: sodium carbonate (also known as washing soda) and hydrogen peroxide (often found in hospital grade disinfectamts). During manufacturing, these two compounds are combined and dried into a stable powder that can be stored safely until it hits water.
It is the pure active ingredient found in commercial laundry soakers and heavy duty cleaners. When you buy it on its own, you are getting just the ingredient, no fillers, no fragrance, no bleach activators.
How it works
When percarbonate dissolves in water, it separates back into its two components: sodium carbonate and hydrogen peroxide. The hydrogen peroxide then releases active oxygen into the solution.
This active oxygen works in two ways. First, it oxidises the molecules responsible for stains (the chemical structures that give stains their colour) breaking them down so they are no longer visible. Second, it attacks organic matter like bacteria, mould spores and food residue, making it effective for both cleaning and disinfecting.
The washing soda released at the same time is not just a bystander. It raises the pH of the solution to around 10-11, which creates an alkaline environment that helps break down grease and improves the overall cleaning performance.
That fizzing and bubbling you see when it hits hot water, that's the oxygen being released. When it is fizzing, it is working.
Why hot water matters
Sodium percarbonate needs heat to activate properly (get into its cleaning state). Warm to hot water accelerates the release of active oxygen, which is what actually does the cleaning. Cold water slows the reaction down so much that you will not see meaningful results.
A rough guide:
| Warm (around 40C) |
Most laundry, coloured fabrics |
| Hot (above 40C) |
Heavily stained laundry, towels, tea towels |
| Boiling |
Oven racks, BBQ grills, stainless steel, heat-resistant items Fastest action, best for tough built-up residue |
Always use the hottest water that is safe for whatever you are cleaning.
When to use it
Sodium percarbonate is one of those ingredients that keeps coming up because it handles so many different jobs.
Laundry and fabric care
- Soaking whites and removing yellowing
- Stain removal on colourfast fabrics
- Boosting laundry powder for heavily soiled loads
- Refreshing towels and tea towels that have gone dull or musty
- Cleaning reusable nappies and sports uniforms.
Kitchen and home
- Degreasing oven racks, BBQ grills and baking trays
- Deep cleaning plastic containers and food storage
- Removing staining from ceramic and porcelain
- Freshening stainless steel.
Bathroom and general cleaning
- Deep cleaning grout
- Whitening silicone
- Treating surface mould on tiles
- Deodorising and freshening bins and drains.
Used in these recipes
Its also perfect to supercharge Oven Cleaner which is the Multi-Purpose Cleaning Paste
How to use it for soaking
Soaking is where sodium percarbonate really performs. Remember to use an oversized bucket as the solution will fizz and rise as oxygen is released
How much to use: 1 to 2 tablespoons per litre of warm or hot water covers most jobs. For heavily stained items, a slightly stronger solution will give better results.
How long to soak:
- Warm water: 2 to 6 hours
- Hot water: 30 minutes to 2 hours
- For stubborn stains, longer soaking times improve results
If the water cools significantly during a long soak, the cleaning action will slow down. For tough jobs, topping up with hot water partway through makes a difference.
A few practical tips
- For laundry, soak first and then wash as normal or use as a laundry booster in your DIY laundry powder
- Freshly mixed solutions work best. Do not make a batch and save it for later, once you have finished discard the remaining solution
What you can use it on
Sodium percarbonate is suitable for a wide range of surfaces and materials:
- White clothing and colourfast fabrics
- Tea towels, cleaning cloths and reusable wipes
- Towels, sheets and bedding
- Reusable nappies and sports uniforms
- Plastic containers and food storage
- Stainless steel items
- Oven racks and BBQ grills
- Ceramic and porcelain
- Grout and tiles
Always check care labels and do a small spot test if you are unsure about a specific fabric or surface.
What to avoid
Sodium percarbonate is not suitable for everything. Avoid using it on:
- Aluminium: reacts with alkaline solutions and causes pitting and discolouration
- Delicate fabrics: In fabric like silk and wool the alkalinity damages fibres
- Waxed or polished wood: strips wax and finish
- Fibreglass: can cause etching
- Painted surfaces: can strip or dull paint over time
-
Natural stone such as marble, travertine and limestone: alkaline solutions can damage stone surfaces over time (acidic cleaners are more commonly cited as the risk with stone, but repeated alkaline exposure can also cause issues
Warnings and safe use
Sodium percarbonate is considered low-hazard when used correctly, but it still deserves respect.
- Keep out of reach of children and pets
- Avoid inhaling the dust when measuring or pouring
- Avoid contact with eyes, rinse immediately with water if it occurs
- Do not ingest
- Do not mix acids like citric acid or vinegar, this will neutralise the cleaning action
- Never store it once it has been mixed with water as it continues to react and lose effectiveness, and can cause pressure in sealed containers
Storage and shelf life
Store sodium percarbonate as a dry powder in a sealed, airtight container in a cool, dry place. Moisture and humidity are its enemies, even small amounts of moisture in a container will start to degrade it over time.
Stored correctly, it has a shelf life of around 2 years. You will know it has degraded if it has clumped, stopped fizzing when added to hot water, or lost its effectiveness.
Once mixed with water, it begins to break down immediately. Always mix fresh and use promptly.
Eco credentials
One of the reasons sodium percarbonate sits on the Under Your Sink approved list is what it leaves behind when it is done.
After releasing its active oxygen, it breaks down into three things: sodium carbonate (washing soda), water and oxygen. All three are biodegradable and benign. There is no chlorine, no synthetic fragrance, no optical brighteners and no phosphates.
It is generally considered safe for greywater systems and septic tanks when used in normal household quantities. It is also produced without the significant environmental concerns associated with chlorine bleach manufacturing.
This does not mean it is without impact as manufacturing any ingredient has a footprint. But as cleaning ingredients go, it is one of the cleaner options.
A bit of history
Sodium percarbonate was first synthesised in the late 19th century, around 1899. For decades it remained a relatively obscure compound, but from the 1970s and 1980s it began appearing in commercial laundry and cleaning products as a more environmentally acceptable alternative to phosphate-heavy detergents and chlorine bleach.
In Australia it became widely known through products like Napisan. In the US, OxiClean popularised it for home use. Both products are built around the same active ingredient (sodium percarbonate) surrounded by varying amounts of fillers, fragrances and additives depending on the brand.
Buying it pure means you get the ingredient without the extras, and you can decide what to do with it yourself.
Once you start using sodium percarbonate it's hard to go back to buying separate products for laundry soaking, dishwashing, stain removal and deep cleaning.
