When you create cold process soap, one of the most important things to consider is its pH level. Freshly made soap is often alkaline, and if the pH is too high, it can irritate or dry out your skin. That’s why testing the pH of your soap is crucial to ensure it’s safe for use. The last thing you want is to spend hours making beautiful, homemade soap only to discover it’s too harsh to use!
In this guide, we’ll break down everything you need to know about cold process soap pH testing: Why it’s important, how to test it properly, and how to interpret the results to make sure your soap is safe and gentle.
Why Test the pH of Your Cold Process Soap?
When you first make cold process soap, the pH can be relatively high—sometimes as high as 10-12. While this is perfectly normal right after saponification, it doesn’t mean the soap is ready for use. As your soap cures, the pH decreases and stabilizes to a skin-friendly level, usually around 9-10.
Testing the pH is important because:
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Ensures safety: Soap with a pH that is too high can be too harsh for your skin, causing irritation, dryness, or even burns.
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Indicates proper curing: Testing the pH is a good way to know that your soap has undergone proper curing and the saponification process has been completed.
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Helps balance your recipes: If your soap consistently tests with a higher pH, it could indicate that your recipe needs adjustments (too much lye, for instance).
By testing the pH, you can confidently use or give away your soap, knowing it’s safe for skin contact.
How to Test the pH of Cold Process Soap
There are several methods to test the pH of your soap, ranging from simple test strips to more accurate pH meters. Here’s how to test your soap’s pH using the most common methods:
1. pH Test Strips
pH test strips are one of the easiest and most cost-effective ways to test your soap’s pH. These strips are widely available and can be found at most craft stores or online.
How to Use pH Test Strips:
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Wait for your soap to cure: It’s essential to wait at least 4-6 weeks for the soap to cure. Testing fresh soap (before it has had time to cure) will give inaccurate results.
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Cut a small piece of soap: Take a small sliver of your soap to test. It’s best to test a cut piece that has been exposed to air for a few days, as the surface moisture evaporates, giving a more accurate reading.
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Wet the soap: Moisten the soap with a small amount of distilled water. This helps to dissolve some of the soap’s alkalinity so the test strip can react accurately.
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Dip the test strip: Gently dip the wet soap into the pH test strip, making sure it’s submerged for a couple of seconds.
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Compare the results: After a few seconds, compare the color change on the strip to the color chart provided with the test strips. The color will correspond to a pH level, typically ranging from 1 to 14.
Ideal pH for Soap:
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For cold process soap, the pH should generally be between 9 and 10. This range is safe for the skin and ensures the soap is gentle enough for everyday use.
2. pH Meter
A pH meter is a more accurate and precise method for testing your soap’s pH, but it can be more expensive and requires more care to use properly.
How to Use a pH Meter:
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Prepare the soap: Like with the test strips, wait for your soap to cure for 4-6 weeks before testing.
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Dilute the soap: You will need to dissolve a small amount of your soap in distilled water to get a more accurate reading. Aim for about 1 gram of soap for every 10 milliliters of distilled water.
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Calibrate the pH meter: Before use, calibrate your pH meter according to the manufacturer’s instructions. This typically involves testing it with a solution of known pH.
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Measure the pH: Submerge the electrode of the pH meter into the diluted soap solution and wait for the reading to stabilize.
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Record the pH: The meter will give you a precise pH reading, usually within a decimal point, which is great for checking whether your soap is within the ideal range.
Ideal pH for Soap:
Just like the test strips, the ideal pH for soap should be between 9 and 10.
3. The Tongue Test (Not Recommended for Sensitive Skin)
Some soap makers use an old trick of testing the pH by lightly touching the soap with their tongue. This is not the most reliable method and is definitely not recommended for sensitive skin, but it can give you a general idea of how harsh your soap may be.
How It Works:
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Place a small amount of soap on your tongue: Gently touch the edge of a soap bar or a small sliver to your tongue.
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Interpret the sensation: If the soap feels slippery and mild, it’s likely to have a lower pH (close to 9-10). If it feels harsh or burning, it’s likely to have a higher pH (greater than 10).
While this method may give you a rough idea, it’s not as accurate as using pH strips or a pH meter, and it’s not a recommended practice for serious soap makers.
When Should You Test the pH of Your Soap?
Timing is everything when it comes to pH testing:
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After 4-6 Weeks of Curing: This is the standard waiting period before testing. During this time, the saponification process will complete, and the soap will have lost excess moisture, making the pH more stable.
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If You Suspect an Issue: If your soap seems too harsh or you’ve experienced issues like cracking or separating, you may want to test the pH earlier, although this isn’t ideal.
What to Do If Your Soap’s pH is Too High?
If you test your soap and find that the pH is higher than the recommended 9-10 range, there are a few things you can do to adjust:
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Let It Cure Longer: Sometimes soap just needs more time to cure. The pH will often decrease as the soap continues to dry and the saponification process completes.
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Rebatch Your Soap: If your soap is still too harsh after curing for an extended period, you might need to consider rebatching the soap by melting it down and adding more oils to balance out the lye content.
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Check Your Recipe: High pH can sometimes be caused by too much lye in the recipe. Double-check your measurements and consider adjusting the lye-to-oil ratio in future batches.
Conclusion
pH testing is a crucial step in ensuring that your cold process soap is safe, gentle, and effective. By following the right steps and using the correct testing methods, you can make sure your homemade soap is ready to use without any concerns about irritation or skin damage. Whether you use pH test strips, a pH meter, or just trust your senses, understanding and managing the pH of your soap is key to crafting high-quality, skin-friendly bars.
So, take your time with the curing process and test your soap’s pH before you use it.