Quick Recipe (full recipe below!)
Spread baking soda on a baking sheet and bake at 400°F (200°C) for 30 minutes to 1 hour, stirring once halfway. The heat converts baking soda (sodium bicarbonate) into washing soda (sodium carbonate).
What is washing soda?
Washing soda is the common name for sodium carbonate (Na₂CO₃), also called soda ash. It’s a highly alkaline natural cleaner (pH of about 11) that softens hard water, cuts grease, and boosts laundry detergent.
However, unlike baking soda, it’s very caustic and not edible, so wear gloves when handling it.
You’ll find it in the laundry aisle, or you can make it at home from plain baking soda. Several of the homemade cleaning recipes here on Nature’s Nurture call for it, and this post covers everything: what it is, how it differs from baking soda, how to make it, and where to buy it.
Baking Soda vs. Washing Soda: What’s the Difference?
| Baking Soda | Washing Soda | |
|---|---|---|
| Chemical Name | Sodium bicarbonate | Sodium carbonate |
| Formula | NaHCO3 | Na2CO3 |
| pH | ~8.3 (mild) | ~11 (strong) |
| Safe to eat? | Yes | No |
| Best for | Cooking, deodorizing | Heavy cleaning, water softening, laundry |
| Where to find | Any grocery store | Laundry aisle or make from baking soda |
How to Make Washing Soda
Equipment
- baking soda
Ingredients
- 1 shallow metal pan not aluminum as it reacts to baking soda and washing soda
Instructions
- Preheat oven to 400°F (200°C)
- Place baking soda on the pan and spread it across in a flat layer.
- Bake the baking soda in the oven for about 30 minutes, stirring it up every 10 minutes to ensure it bakes evenly.
- You'll know it's done when it starts to change composition: it will look more dull, grainy, and won't clump at all.
Notes
Caution
Washing soda should be handled with care, as it is very caustic. Always wear gloves if handling it directly, and never inhale the dust particles (wear a mask if needed).
The Science of Turning Baking Soda into Washing Soda
The process that turns baking soda into washing soda is a nifty thing called thermal decomposition.
Baking soda isn’t very stable at higher temperatures. When you heat it to around 400°F (200°C), it breaks down into three things: washing soda (sodium carbonate, Na₂CO₃), carbon dioxide gas (CO₂), and water vapor (H₂O).
The gases escape into the air, leaving behind a more alkaline, more powerful cleaning agent.
Chemically, the reaction looks like this:
2 NaHCO₃ → Na₂CO₃ + CO₂ + H₂O
You can actually observe the change as it happens. The powder becomes drier and more grainy, and it loses about a third of its weight as gas escapes.
If you dissolve a little in water, the difference is even clearer: washing soda produces a much more alkaline solution than baking soda (you can test it with pH strips!). Another quick test: add vinegar. Baking soda fizzes vigorously, while washing soda produces much less bubbling.
It’s a great example of how a bit of heat can completely change the chemistry—and usefulness—of a common household ingredient.
Where to Buy Washing Soda
Here are a few places to look for washing soda before you decide if you need to make it at home.
- Grocery or big box stores: It’s usually in the laundry aisle next to all the laundry boosters.
- Pool cleaner aisle: The brand name is AquaChem. Just make sure the only ingredient listed is sodium carbonate!
- Online sources: You can also find it at Amazon. Or for my fellow Canadian readers, you can also find it at Well.ca.
What Can You Make with Washing Soda?
- Liquid Laundry Detergent – A simple 3-ingredient recipe that costs pennies per load and actually works on tough stains.
- Powdered Laundry Detergent – Use your freshly made washing soda in this homemade powder laundry detergent; pennies per load and zero added fragrance.
- Laundry Fresheners – Natural ways to keep your laundry smelling fresh without synthetic fragrances or dryer sheets.
- Dishwasher Detergent Powder – A non-toxic powder that cuts grease without the chemicals found in store-bought pods.
- Laundry Buildup Remover – Washing soda is the workhorse ingredient in laundry stripping—the deep-clean reset for towels, bedding, and built-up gym wear.
Washing Soda FAQs
Trusted alternative to homemade cleaners
For those times you’re not in the mood for homemade, I’ve just discovered a pretty neat alternative that’s not only safe and non-toxic, but low-waste and eco-friendly as well!
TrulyFree makes refillable cleaning products that are safe and sustainable. They work on a subscription model, but unlike other subscriptions you may have tried, there are no commitments and you can always change your products or delivery date.
Your first order automatically includes a reusable bottle or jug along with the cleaning solution, and you’ll only need to order the refills after that. TrulyFree seems to have really figured out the right balance between safety sustainability. And they have probably the widest selection of natural cleaning products I’ve ever seen from one company.
I’m so impressed by TrulyFree and what they stand for, and excited to share that you can use the code: NURTURE30 and get 30% off your entire order!
Thanks for this info, since Arm & Hammer is probably stopped making it stores have stopped selling it cuz it takes up too much space and real estate on shelves.
Is there a special way of disposing left over washing soda? Or does it never go bad, and it can be used till gone?
That’s a great question, Kathleen! As long as it’s stored in a dry environment, washing soda should stay good indefinitely.
Even though my local stores carry washing soda, I have found it is a lot more economical to buy baking soda and create it.
I just started making my own laundry soap. I use castile lavender bar soap and use baking soad and oxyclean mixed in it. I use vinegar with lavender essential in it for fabric softener. Is that ok? Non toxic laundry soap is expensive no matter where you buy it. No emails please.
You’re right, unfortunately non-toxic detergents are more expensive than conventional ones. Your homemade recipe looks just fine. I used homemade laundry soap for a long time before I stopped for good because I felt it was causing a buildup on our laundry. You can read more on that here, if you’re interested.
Can you put the baking soda on wax or parchment paper? Thank you.
Parchment paper should be fine!
Thanks for all the help you give. I need to make home made toilet cleaner, could you kindly tell me what to include?
I’m working on a recipe specifically for toilets, but for now I use my all-purpose cleaner sprayed into the toilet, then I pour about 1/2 cup of baking soda in the toilet, and scrub with a brush.
For those who can’t find washing soda locally, I buy it on line from rural king. Now just a concerned question. I use washing soda with my laundry detergent I didn’t know it was dangerous. Do I risk harming family by using it in the washing machine? I tend to use with warm or hot water washes, not cold. I appreciate your reply.
Hi Barbara, it’s totally fine to use it in the washing machine since it is very diluted and it’s rinsed away, so it never comes in contact with your skin. As long as you’re not eating it, rubbing it all over your skin, or inhaling it directly, you should be ok. 🙂
Hola Sarah, muchas gracias por compartir tus recetas con productos no tóxicos , saludos desde Monterrey, México
Por nada, Tenchis!
For Canadian readers: I buy my washing soda from Home Hardware. It is listed as “Arm & Hammer 3kg So Clean Laundry Detergent”. It is a blue box that says “So Clean! Super Washing Soda” and is 25% cheaper than buying from well.ca. Once you know what the box looks like (look at it online), you might find it in another local store.
But if you are already buying other stuff from Well.ca (they are great and I use them regularly), it is not an expensive item either way. They also sell a smaller package (2 kg) which may be your preference.
I have also found it listed in pool stores and at online chemistry-supply stores, but I love going to Home Hardware – an old, cramped store that has EVERYTHING and still looks like it did when my Grandfather used to shop there. The sales clerks can put their finger on anything immediately among all the piles of stuff and will gladly order something if it is not in stock.
That was super helpful, Wendy, thank you! It’s funny, I’ve been living in Canada for over 8 years, and I’ve never gone into a Home Hardware store even though I see them all the time! I think you just motivated me to check it out, haha 😉
Sounds like Washing Soda is a dangerous powder if inhaled or exposed to your skin. Is it as dangerous as I am implying??
If you have sensitive skin, you should definitely handle it with gloves. But if you’re just scooping it with a measuring cup and not actually digging in with your bare hands, it should be fine. Also, it tends to make lots of dust if you’re stirring it vigorously, so that’s why there’s a warning about inhaling it. Basically, don’t mix it with your bare hands (use a spoon or cup, etc), and don’t put your face right over the pan and inhale the dust directly, and you should be fine. 🙂
Why do you use two forms of Castile soap one flakes and liquid castile soap?
Hi Lucy, the bar soap is added to help give the end result a slightly thicker, gel-like consistency. You can probably replace the bar soap with liquid (though I don’t know how much to use), but I’m not sure how it will turn out since I haven’t tried it. I’m fairly sure it would still work, though.
Thank you for the clear instructions!
You’re welcome, Kathleen!
Wow, this great! Thank you! I am so excited to do this with my daughter!
You’re welcome, Lynsey! Just remember that washing soda should be handled with care – so wear gloves and don’t breathe it in directly.
How can I clean my pillows in a front loading washer?
A quick Google search has a long list of results, but this one has a great tutorial: http://askannamoseley.com/2014/09/how-to-wash-pillows-in-a-front-load-washing-machine/
Thanks so much, I was getting desperate. This information is a lifesaver.
Glad I could help!
How much Washing Soda do you put in with your Laundry Detergent?
You can find links to all the recipes that use washing soda, at the bottom of this post. 🙂
Thanks! Been, making my own for years but finding the washing soda has become more challenging as supply seems to not be keeping up with demand and the shelf is more often empty than not anymore. Now I can buy that huge bag from the bulk distributor and make it. Awesome!
You can tell if you have washing soda as it chemically reacts with hard water. It precipitates the calcium and the reaction heats the water. Baking soda and water do not react. It stays the same temperature and settles on the bottom. It’s an easier way for me to tell if it’s changed.
Thanks for that info, Sara! Someone commented before that washing soda felt hot on her wet hands, so this explains it!
My daughter and her friends shared your site with me. They all love it! It’s rather lovely and I needed this one on the washing soda. Thank you!!
Thanks Mommasita4 🙂
I tried this. I cooked it for 2 hours because it wouldn’t change. I have washing soda on hand and feel its almost a gritty feeling. after baking it still is powdery feeling. Has anyone had this problem? I don’t know what to do.
Thank you so much! U have no idea how much this post helps me! I’ve been wanting to make my own paper naturally, but every recipe calls for caustic soda or washing soda. But all the companies that sell those use chemical processing to produce them. But I have a Bob’s red mill baking soda that uses NO chemicals. So now I cant just making my own washing soda and use that to finally complete my goal! Thank you again! And God Bless You!!!
Hi there,
I am looking for washing soda so I can dye some fabric. I will try changing plain old baking soda into washing soda and see how my colors turn out from dyeing them.
Ruth
Great experiment, Ruth! Would love to know how/if it worked out!
Cool! I used to be able to find it at my local walmart but now I can’t find it anywhere! Thanks I can make my own detergent again! 🙂
Here is some back-up in case anyone is doubtful:
http://antoine.frostburg.edu/chem/senese/101/inorganic/faq/carbonate-decomposition.shtml
Since we can’t set our ovens to 392 deg F (or maybe you can), 400 deg F is the way to go.
we just use baking soda in our washing machine – what is the advantage of washing soda versus baking soda for laundry?
It’s just a stronger, more alkaline version of baking soda, and packs a stronger cleaning punch. It also works great on getting mildew smells out of towels. Lots of people just use baking soda in their detergent recipes, so if it works for you, no need to change a good thing! 🙂 I actually use both – washing soda in the detergent recipe, and I also add 1/4 cup of baking soda to help soften clothes and regulate the ph level of the water.
I love this tip! I never see washing soda in the stores and there’s so many recipes I want to make that use it. Thanks!
You’re very welcome, Tracy!
Thanks! Needed washing soda for a science experiment, and this saved that day!
I have a quick question. If I put the converted baking soda to washing soda in a seal container will it remain washing soda. I am experimenting with different recipes and don’t want to use it already. I also am having a difficult time finding washing soda. Do you have a recipe for dishwasher detergent?
I’m not sure, but I think if it’s stored in a cool, dry place it should be ok.
And there’s a dishwasher detergent recipe in this post: https://naturesnurture.co/non-toxic-household-cleaners/
Hello!
I have been experimenting with the “baking Sodium Bicarbonate into “Sodium Carbonate” procedure for a little while… I have 2 potential tips and/or questions 🙂
1. With the “recycling” concept in mind, I did try to recycle my old “fridge baking soda” as others have mentioned and it doesn’t seem to make a difference with in the final product, the odors probably disappear with the heat and evaporation.
I googled it several times and just found the question/proposition, but never an actual answer… While in the fridge, it absorbs odors as well as water from condensation. I would assume it doesn’t change it’s chemical structure and that you would just need a little more time in the oven to achieve the same results…
—> can anyone corroborate this with scientific facts?
2. I didn’t calculate the cost effectiveness as far as the energy used by the oven while making soda ash, but I agree that, in the winter, residual heat for the house could be an argument… 🙂 ) From that thought, came my next idea: I have a self-cleaning oven (extremely high temperatures reduces food grime to ash ), I don’t use it often, but it works. I thought I might as well turn other good thing to ash next time I do it – which should be pretty soon – and putting baking soda on the bottom part of the “clean” broiling pan that came with the oven ei coated for this process!
—> My question is: Does anyone know if it can be over-baked, both in time and temperature, kill it all together or produce something else? Any thoughts?
I doubt the latter but…To be safe, I searched this as well, never found an answer. The proposed times vary from 30 min to 2 hours and there are some arguments about what temperatures are “too low”.
3. (oups! I lied… 3 questions) Besides the visual aspect, is there other clues to verify one has succeeded in transforming it? I haven’t used it in soap recipes yet…
Thank you!
Why does baking soda need to be converted? Why can’t you just use the baking soda instead??
Baking soda and washing soda are two completely different products. Some recipes for detergents and soaps call for washing soda, which is why it would be converted if you can’t find it locally.
I LOVE your site, get you by facebook as well as your newsletter.
Thanks for the great work you do….
Thank you thank you what an awesome tip my followers will be thrilled!!