14 Practical ways to prevent and get rid of Soda ash in Soap Making

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Prevent Soda Ash in Soap Making

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In this blog, I would like to share 14 practical ways to prevent and eliminate Soda ash in your cold process soap.  Let us start with understanding what Soda Ash is. Then, i’ll share some tips and tricks in controlling the main factors that contribute to the production of the Soda Ash by-product in your home-made cold process soap recipe.

What is Soda Ash in Soap Making?

Soda ash is a powdery, irregular white ashy film on top or within a bar of cold process soap chemically known as Sodium Carbonate. It is formed when Sodium ions from unsaponified lye reacts with carbonic acid (dissolved carbon dioxide in water) or atmospheric carbon dioxide in the air comes together and precipitate (becomes insoluble). This is typically observed by soap makers within 1-3 days after the pour.

Should I throw my Soap batch?

Soda ash is an aesthetic issue and not a safety risk. Whether you’d like to keep or get rid of it – is just normal and fine. I know that it may be frustrating especially when observed on artisan soaps but beauty is always in the eye of the beholder. Most soap makers learned to “embrace soda ash” because it makes the soap look rustic.

Soda Ash Prevention Tips:

Following the tips and tricks below could help to prevent soda ash in your handmade soap:

1. Temperature control

Prevent Soda Ash in Soap Making


Keep the temperature of the oil blend and lye at almost the same temperature. Try soaping at slightly higher temperature 100​°​F to 120​°F​ (~38​°​C to ~49C). Start at the minimum suggested temperature and experiment the optimum temperature condition based of your soap recipe. Keep in mind that soap making at slightly higher temperature also gives other problems especially when there are other ingredients that could potentially increase the reaction temperature like milk, accelerating fragrance oil, etc.

2. Proper trace identification

Pour at medium trace instead of light trace. Some design requires light trace but if you are a beginner, pouring at light trace normally results to soda ash, false trace and/or oil separation. Properly recognizing the difference between light (thin), medium and heavy (thick) trace is the key.

3. Table Salt usage

Adding table salt in your recipe makes the bar soap harder. If you use too much, salt creates free Sodium ions that could easily react with free carbonates in the soap recipe. Limit the amount to 1tsp PPO or less. In the Enhancer section of www.mysoapcalc.com​/soap salt will be automatically calculated based on your recipe input and according to the suggested limits.

4. High purity Sodium Hydroxide

96% Sodium Hydroxide Purity or higher is good for soap making. Purity less than 96% would mean that your lye have higher amount of Sodium Carbonate and other impurities. Input the purity in “Lye” section 3 in www.mysoapcalc.com/soap​ and it will auto-calculate and correct the amount of Sodium Hydroxide that you need according to the purity of the chemical that you have at hand.

5. Water quality

Use distilled water or demineralized water. Hard water contains high amount of Calcium Carbonate and Magnesium Carbonate. Having other carbonate source in the recipe creates soda ash not only on top of the soap but within the whole bar.

6. Proper insulation

Insulating or covering your soap with thick cardboard or towel, not only keeps the reaction temperature more stable but it also helps to prevent atmospheric carbon dioxide to react with lye.

7. Thin Protective Coating

If you don’t want to insulate the soap due to high-top soap design, worry not, just immediately spray the top with high purity Isopropyl Alcohol (IPA) to help create a protective film on top of the soap layer within 10-15 minutes after the pour. That would definitely do the trick.

Use of Beeswax, Soywax and Stearic acid also adds protective layer in the soap but it will not guarantee the prevention of soda ash, to most it created more problem than a solution especially if these additives are not properly melted and temperature is not properly controlled. This additives requires high temperature soaping to keep the wax properly incorporated in the soap batter. Remember what I said in section 1?

8.  Water discount

Water discounting makes wonders in soap making recipes. If you are a newbie, refrain from water discounting because using lye at higher concentrations makes the saponification process to go faster. When you are comfortable enough and already gained some experience, by all means, go ahead and soap at water discount. At discounted water, you will not see even a tiny speck of soda ash in your soap ever again. The “Water” section 4 of www.mysoapcalc.com/soap​ has a section that says Water discount go ahead and use it. My Soap Calc will do the rest for you.

9. Superfat

Keeping the superfat at 2% to 5% is good. Lye section (Section 3) of www.mysoapcalc.com/soap​ has an input portion for Lye Discount/Superfat at 5% default. You can change it according to your preference. You may want to use high superfat to make the soap moisturizing but as the song goes “too much of something is bad enough.” so try to achieve a well balanced soap recipe.

10. Ungelled Soap

A number of soap makers like gelled soap and some prefers ungelled soap. If you really want to prevent Soda ash in your soap, try med-temperature soaping and don’t gel your soap bars. You can also soap at slightly higher temp but you have to quickly place your soap into the fridge to avoid gel-phase.

BONUS: Soda Ash Removal Tips:

If you’ve done everything and stubborn soda ash is still there, here are some simple tips and tricks that you can try:

1. Steam off soda-ash using a steam iron for 10 to 30 seconds. Soda ash easily dissolves when it comes in contact to water and water vapor.

2. Give a cold wash to your soap and immediately dry the soap. This also creates a shiny finish.

3. Scrub the surface of the soap with damp nylon cloth or stockings.

4. Trim or shave the outer layer of the soap with a planer.


We have a total of 14 ways to prevent, eliminate or get rid of soda ash in your cold process soap.  You can follow some or do the steps in combination. A perfectly balanced soap depends on your preference. If your issue is not a safety risk, you can close one eye, move forward and try to improve. I’m sure you’ll get there!

Let me know about your Soda Ash Experience. Comment down below and share so our Soap Sisters and Bubble brothers can learn from you too. Cheers!

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