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Accurate ph for clay mask
I’ve had an ongoing issue measuring ph with a clay mask formulation. I understand that solids are going to pose a challenge, but did assume my readings would be consistent and somewhat accurate (not fluctuate so much during readings). The product contains Honey, Water (10%), Fuller’s Earth, Glycolic, Citric, Tartaric and Lactic acids, Glyceryl Caprylate, Glycerin, Sodium Levulinate, Sodium Anisate. The ph meter has been calibrated, and even when diluted my readings are fickle. We are shooting for a ph of 3.8-4.
Any suggestions or insights would be most appreciated.
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4 Replies
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try another meter if you can and/or cover the beaker around the electrodes when taking measurement.
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Try using a flat-surface probe, or one designed for high-viscosity products. General purpose electrodes don’t work reliably with high-viscosity/high-solids formulations.
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If dilution is still causing fluctuations something hygroscopic in formula (acids) are absorbing water from the air so try dilution and covering first.I have seen this before.
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Update: We used a 10% dilution and a new electrode. Slope was around 90, and numbers were spot-on so it appears that the electrode was the culprit. Ph turned out to be very close to our intended mark. Thank you so much for the replies - great insight and suggestions I’ll keep in mind if this should come up again.
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