Soothing Baking Soda Oatmeal Bar

  • Difficulty:Intermediate
  • Time:1 hour
  • Yields:2 lbs. of soap

For the ultimate skin-soothing bar of soap, you can’t get much better than this Baking Soda Oatmeal Bar. Made with Castile Rebatch, Oat Extract, Colloidal Oatmeal and baking soda, it has some serious nourishing power. Baking soda provides gentle all-over exfoliation, and oatmeal is renowned for its ability to calm irritate skin. Some customers may prefer this bar unscented so they can enjoy the gentle exfoliation of the baking soda and soothing effect of the oatmeal, but you can certainly add Lavender or Chamomile Essential Oil to give it a mild scent.

Regular soap has a pH anywhere from 8.5 – 10, and this soap is definitely on the low end of the spectrum with a pH of 8. It’s gentle enough for sensitive skin but strong enough to provide plenty of exfoliating cleanliness.

This is also a great recipe for beginning cold process soapers. It uses a rebatch base, which means the soap arrives pre-made and pre-cured; no dealing with lye!  This tutorial uses the double-boiler method, but you can experiment with the plastic baggie technique too. For more on making rebatch soap, check out this Soap Queen TV video.

What You’ll Need:

16 oz. Castile Rebatch
16 oz. Sodium Bicarbonate
3.2 oz  distilled water
.2 oz. Oat Extract
.5 oz. Colloidal Oatmeal
.2 oz. Rolled Oats
.8 oz fragrance or essential oil (optional)
2 lb. Wood Loaf Mold with Liner

Click here to add everything you need for this project to your Bramble Berry shopping cart!

ONE: The rebatch you order from Bramble Berry comes pre-shredded, so you won’t need to worry about that. Set your double boiler on medium heat and add the rebatch. Let the rebatch sit and move on to step 2.

TWO: Mix the baking soda with 3 oz. of distilled water. Stir with a whisk or spoon to combine.

THREE: Add the entirety of the baking soda/water mixture to the rebtach and stir.

FOUR: Add the Colloidal Oatmeal. At this point, the rebatch should start to melt down into more of a paste. If it hasn’t, keep stirring and turn up the heat slightly on the double-boiler.

FIVE: At the Oat Extract and stir.

SIX: Now play the waiting game! After about 20 minutes, the rebatch will start to thicken into a gloppy oatmeal-like texture. That’s what you want. You want to keep your rebatch hydrated, so you may need to add a little extra water if you notice any cracking or if the mixture turns to a clay-like consistency. Keep in mind that the more liquid you add, the softer the soap will be, and the more difficult to pop out of the mold.

We added a tiny (.2 oz) of extra water to keep the soap from getting too dry.

SEVEN: As you can see below, the ideal texture is that of mashed potatoes. At this point you’re ready to spoon it into the mold.

EIGHT: We used a Round Silicone Spoon to scoop the soap into the mold. Because it’s so thick, remember to tamp the mold on the table to eliminate any trapped air bubbles. Garnish with rolled oats.

Wait 2 to 4 days before unmolding. When send our rebatch already cured, so as soon as you cut it’s ready to use right away. Enjoy!


Many of you have been asking about adding baking soda to regular cold process batter. Our research and development team tested a batch using the same amounts of water and baking soda we used in this recipe, and the results are below:

Lye water and baking soda. Those are chunks are undissolved lye!

Lye water, baking soda and oil. Even after vigorous stick blending, the mixture still wouldn’t combine.

So there you have it! These photos definitely speak for themselves. While we don’t know exactly why baking soda reacts so poorly with lye and soap batter, our guess it has something to do with the baking soda and lye neutralizing each other, thereby interrupting the saponification process. When it comes to baking soda and soap, stick to rebatch!

36 Responses to “Soothing Baking Soda Oatmeal Bar”

  1. Cindy Stares says:

    Wow. You guys are always so inspiring!! I wouls love to try this in cold processed soap . Would I add the carb. soda at trace with a small amount of water or to the lye solution? Thanks so much for all you do for the completely addicted soapers in this world.

    By the way Anne-Marie, You Soap Crafting book is amazing. I wish you every success.

  2. Meagan says:

    If I don’t want to use rebatch, would I add the soda/water at trace and discount the lye water?

    • Hi Meagan,
      This is something we’re currently researching. Our team is testing a cold process recipe with baking soda over the next few days, and I’d be happy to get back to you with a response :) Happy soaping!

    • Hi Meagan,
      Our team tested a batch of cold process with baking soda, and the results weren’t so great! We have included photos of the results at the end of the post. Unfortunately, there is just no way to successfully combine baking soda and cold process soap batter.

      • Meagan says:

        Oh no! Well thanks for the experiment anyway. At least now I know. I would’ve been so sad if I had tried it :(

  3. Donna Lee says:

    I love making rebatch soap! Thank you for the new inspiration – can’t wait to try!

  4. Lin says:

    What kind of double boiler are you using? It looks electric, with a dial similar to a crock pot. I’m really interested because I’ve tried finding an electric double boiler before with no luck.

  5. Erika says:

    Everytime I put oatmeal / buds / petals as decoration, the fungi will be grow all over the soap. and if I put decoration sprinkles, they will melt. what should I do if I want to decorate the soap using those things? thank you

  6. Sly says:

    My first thought was how to make this with CP, and I see others have the same idea, but they didn’t ask the question that was on my mind:

    How much Baking soda and colloidal oatmeal do you put in CP? Re….percentage-wise, or for a 2 lb batch like you have above? (same as this recipe?)

    How scratchy is the baking soda and oatmeal? (mild, med, etc exfoliant?)

    Thanks so much for your expertise!

    • Hi Sly,
      That is something we’re currently testing, and I’d be happy to get back to you with an answer. We’ve only ever made baking soda and rebatch, so I’m going to have our team test a CP recipe to give you the most accurate answer possible :)

      As for the baking soda and oatmeal, they are both very mild exfoliants. The little granules are finer than sand!

      I hope that helps. Thanks for your patience as we test a baking soda and CP recipe :)

    • Hi Sly,
      Our team tested a batch of cold process with baking soda, and the results weren’t so great! We have included photos of the results at the end of the post. Unfortunately, there is just no way to successfully combine baking soda and cold process soap batter.

  7. Cheri Slaughter says:

    Can I use a different mold? I have your 12 bar square silicone mold. Also, what does the oat extract do? Does it provide any scent?

    • Hi Cheri,
      Of course you can use a different mold :) Simply run the recipe through our lye calculator and resize it to get the correct amount you need for whatever mold you’d like to use.

      The oat extract does not provide any scent — this bar is unscented! Oat extract is very soothing for a variety of skin types, including baby skin and mature skin. It is also especially moisturizing too! We included it for those properties, and you can definitely make this recipe without the oat extract :)

      Lye Calculator:

  8. Cheri Slaughter says:

    Also forgot to ask, can I substitute the oat extract or make it without it?

  9. Gwen says:

    I love your blog, it’s always so much fun to read. I learn so much about crafting a lovely bar of soap.

    I read a lot of the comments about using baking soda in CP soap. I don’t think it will work chemically (chemistry was my major). Baking soda (sodium bicarbonate) is an amphoteric compound, this means it can work as either a base or an acid under the right conditions. When you add it to a strong base like Lye (sodium hydroxide), it will react with the lye to produce carbonates. Carbonates will just muck up the soap, and not all of the desired oils will saponofy, leaving you with an over super-fatted soap. Rebatch works because all the lye is used up in the saponification reaction, and isn’t around any more to react.

  10. Sharon says:

    Once the soap is unmolded when can it be used?

  11. Miranda says:

    I’m wondering if you can somehow make this into a liquid soap instead of a bar? What should I substitute? Thank you!

  12. Jean says:

    I’ve made this recipe 3 times and each time the resulting bar is coarse, grainy (with the baking soda) and more of a white color than the color shown. It doesnt feel soothing in the shower, it’s scratchy.I’m wondering what I need to do to get a soothing bar. I used your round silicone mold, not the loaf mold, and carefully followed the recipe.Maybe I need to add more water to the baking soda to account for east coast climate differences? Thanks for any tips.And, your blog is an awesome educational tool!

    • Amanda says:

      Hi Jean!

      I’m sorry to hear you were not 100% happy with this recipe. If you’d like the bar to be less exfoliating, I would recommend adding half of the baking soda. You may also need to add less water because of this. I would recommend cutting the water amount in half as well, then adding a little more if necessary. The oat extract and colloidal oatmeal amounts can stay the same :). Don’t worry too much about the color :)

      I hope this helps!

      -Amanda with Bramble Berry

  13. […] Soapqueen - Easy Recipe For Soothing Baking Soda Oatmeal Soap […]

  14. […] I was making a new batch of soap with a new recipe  by Brambleberry’s Soap Queen, Soothing Baking Soda & Oatmeal Bar  and discovered, once again, that I was missing 2 ingredients, oat extract and colloidal oatmeal. So […]

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