How to test the pH of soap with our water testing kits

Often customers ask, how they can test the pH of soap. Below are some simple instructions.

Testing the pH of soap is an easy way to ensure that soap is safe to use. The pH scale shows the strenght of an acid (6 and below), neutral (7) or base (8 and above).

Soap should have a reading of 7-10. Soap with a high pH (above 10) is likely to be too harsh, or lye-heavy, for use (lye has a pH of 14). Free lye in soap is just as caustic and painful as the lye water - so it is critical to test the pH of soap, especially when it is homemade.

Option 1:

What you need: wide range pH test strip 0-14 test, deionised or distilled water

Step 1: Dampen a test pad with distilled/deionised water and then touch the pad to the bar of soap for a few seconds.

Step 2: Soak the test strip in the test solution for half a second and compare it with the colour chart to read the result.


Option 2:

What you need: wide range pH test strip 0-14 test for water

Step 1: Get the bar of soap wet, and then let a drop of water run from the bar to the test area of the test strip. 

Step 2: After half a second and compare it with the colour chart to read the result.

If your soaps' pH is between 7 and 10 then it is safe to use. If it is above 10, proceed with caution. A very high pH indicates that the soap is dangerously heavy in lye, and should not be used.












Disclaimer: Only opinions based upon our own personal experience or information detailed in academic journals or other publications is cited. This has been done exclusively for anyone who is interested in this subject but is not intended to replace proper analysis. We cannot accept responsibility and liability of any kind which may result from the application of this information. We always recommend to consult an expert to discuss any test results or get a full recommendation on the specific subject and specific to your situation by an expert.

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There are strict standards for the quality of drinking water within Europe mainly laid down in the EU Drinking Water Directive (98/83/EC). These are based on advice from the World Health Organisation (WHO).