How to Test the pH Level of Hand-Made Soap

There are a number of ways to test your soap. The old, at-home method is to simply touch the tip of your tongue to a bar of soap. If it tastes like soap, then everything is in order. If, however, your tongue gets a sting, this means your soap is lye-heavy and should be thrown out. After you touch your tongue to the soap, rinse your mouth with water or mouthwash. You can also buy litmus test strips to test your soap. The pH scale ranges from 1-14, with bases (alkalis) like lye on the low end and acids like vinegar at the high end. Your soap should be neutral on the pH scale—somewhere between 6 and 10. To test your soap, put a few drops of water on the surface of your soap and rub the test trip on it. Follow the instructions on the package of test strips. You can also buy drops of a solution called phenolphthalein online or at pool supply stores. You will put a few drops of the substance on your soap, and the color it turns will tell you the relative pH. Again, follow the directions of the bottle of phenolphthalein as each brand is different. Soap is notorious for being hard to measure the pH because the surface of the soap often yields completely different results than the center. Measuring the center accurately requires high-tech equipment. If you want to invest in an electronic pH meter, knock yourself out. However, in my opinion, it is easy to see if your soap is safe based on observing its appearance, smell, and taste.