pH Calibration

It’s important for the cosmetic formulator to have accurate pH readings of the formulation. A pH meter will need to be calibrated. The electrode is sensitive and degrades over time and does not give an accurate pH reading. For how often to calibrate the pH meter depends on frequency of use. If it’s used frequently, it should be calibrated twice a month. If the pH meter has been inactive for awhile it should also be calibrated. It is important and simple to calibrate a pH meter.

Standard Buffer Solutions

Standard buffer solutions are used to calibrate a pH meter at room temperature (78F / 25C). Buffers are solutions of a known pH and resist changes in pH. They come in pH 4, pH 7, and pH 10  They come in standard colors so they don’t get mixed up, pH 4 is pink, pH 7 is yellow, and pH is blue. For cosmetic formulations you only need a pH4 and pH7 buffer solution. When the pH is above 7 then you will need a pH 10 buffer solution.

Easy Steps for How to Calibrate a pH Meter

Most pH meters are similar to calibrate. Refer to the pH meter manual for the model of that meter.

1. Always start with the pH 7 yellow buffer solution. Turn on the pH meter and place it in the buffer solution and press the calibrate (CAL) button, until CAL appears in the display. The pH meter recognizes the solution and calibrates to that value. The pH reading flashes on the display. When it is complete, it will display End (or SA and then End) depending on the model of the pH meter. It then returns to the normal operation mode. Remove pH meter.
2. Second is the pH 4 pink buffer solution. Turn on the pH meter and place it in the buffer solution and press the calibrate (CAL) button until CAL appears in the display. When it is complete, it will display End. Remove it.
3. If you also want to do the pH 10 blue buffer solution. Turn on the pH meter and place it in the buffer solution and press the calibrate (CAL) button until CAL appears in the display. When it is complete, it will display End. Remove it.

That’s it. The pH meter is calibrated

Always keep the pH meter electrode moist. It is recommended to store it in the pH4 buffer solution.

Tips if the pH meter is acting up:

1. Go to the website of the pH meter brand for troubleshooting, refer to the manual or contact them.
2. Sometimes it helps to remove the battery, turn the meter on, replace the battery, and calibrate it.

LEARN MORE

Learn more in-depth about pH testing and adjusting and formulating cosmetics by taking a Formulation Course here.