How to Test the pH of Handmade Soap, Step by Step
How to Test the pH of Handmade Soap
Cure time, simple strip testing, safe ranges.
Correct pH keeps cold-process soap gentle and effective. Follow these steps to cure, test, and confirm a skin-friendly bar.
Step-by-step pH test
- Allow to cure for 4–6 weeks. Saponification and water loss continue during this period.
- Get pH strips from a reputable retailer or chemist.
- Create a lather by wetting a small piece of the cured soap in your hands.
- Touch the strip to the lather, ensuring full contact for an accurate read.
- Compare the colour to the strip chart immediately.
Safe targets: Aim for pH 8–10. Above pH 11 is too alkaline and may irritate skin, reformulate or rebatch if readings are high.
Why pH matters
- Saponification: Oils react with lye to form soap, producing a naturally alkaline product.
- Skin’s acid mantle: Your skin barrier is slightly acidic. Well-cured soap in the 8–10 pH range cleans without excessive disruption.
- Comfort and longevity: Proper pH improves skin feel and helps bars age well.
Quality control tips
- Test multiple spots or bars from the same batch for consistency.
- Use fresh, wide-range pH strips and store them sealed, away from humidity.
- If pH is high, allow more cure time or consider rebatching.
- Record date, recipe, water %, temps, readings for your making journal.
Is neutral pH (7) better?
Not for true soap. Cold-process bars are naturally alkaline. Aiming for pH 8–10 is standard for gentle cleansing.
Safety: Wear gloves and eye protection when handling fresh soap or lye solutions. Only test fully cured bars for final pH.
Questions about testing or rebatching, message us on WhatsApp, we’re happy to help.