pH Testing - 3 Ways to Test Your Homemade Natural Soap

The most important aspect about making your own natural soap is to get the chemistry right. Not enough lye will create a soft bar that may never cure or take a long time to cure. Too much lye will cause a caustic bar, which would remove any natural oils from your skin to possibly causing red skin, or even burning, from little pockets of lye water.

I have always used phenolphthalein, (pronounced: fee no fah thay leen) a liquid that smells like nail polish remover. It usually comes in a dropper bottle, is inexpensive, and you simply allow a drop on the top of your soap. If it turns bright pink right away, then there is a high ph problem with your soap. If it turns pinkish after a new minutes, then this would be usual as the soap is still caustic and not fully neutralized. But if it has no color at all, this will indicate a pH normal bar - perfect.

I tried the litmus papers but preferred my phenolphthalein. Although many soapmakers swear by these. These test strips need you to wet a bar of the soap till there is some bubbles and place the strip on the bubbly part of the bar. After a few hundred bars of soap, you will have an expert eye and be able to tell by looking if there may be a problem. But in the beginning, I would test every slab.

The pH scale ranges from 1 - 14, and the aim for your soap will be between 6 - 10. Generally the numbers you will want for a mild soap would be 5 - 8. For a stronger hand soap, aim for 8 - 10, and for grating later for laundry, you'll want a reading of 10 - 12. Some soaps that test high initially will have lower pH levels later, so put it aside and retest in a couple of weeks. If you are using phenolphthalein, then the color you would be looking for would be clear for a mild soap, light pink for a hand soap, and dark pink for a laundry soap.

Some people use little electronic pH testers. They are considered more accurate and need to be buffered, or calibrated, before using. This method is also the most expensive.

Every so often, when not mixed properly, lye water will come to the top of the soap slab and look like harmless water or oil. This water is extremely caustic, be very careful when moving the slab around in the mold that none of this drips.