Sodium Hydroxide, Pearls, 1 kg

Sodium hydroxide, microbeads

Sodium hydroxide is an alkaline substance without which it is impossible to make solid cold-process or hot-process soap. Its aqueous solution reacts with fats and oils and converts them into soap. This reaction is called saponification. A second application is as a pH adjuster: a small addition to the water phase raises the pH of rinse-off products when the resulting mixture is too acidic.

A 1 kg pack is sufficient for multiple batches of soap or for an extended period of pH adjustments.

Key properties

• Saponification of fats – a sodium hydroxide solution with vegetable oils and butters produces solid soap. The quantity is calculated from the saponification values of the fats used, not estimated.
• pH adjustment – in the water phase it raises the pH of rinse-off products that need to be shifted towards alkaline values.
• Solubility – dissolves in both water and alcohol. It is added to the formulation as a solution, not in solid form.
• Cosmetic and technical grade – suitable for soap making and for pH adjustment in cosmetic formulations.

Use in formulation

In soap making, the microbeads are first dissolved in weighed water and only the finished solution is mixed with the oil phase. The procedure is always the same: the hydroxide is poured into the water, never the other way around. The solution heats up during dissolving, so work is done in a container resistant to alkalis and the solution is left to cool to the temperature required by the specific recipe. The required quantity is calculated from the saponification value of each fat in the formulation, typically using a soap calculator, where the fat excess (superfat) is also set.

As a pH adjuster it is added in the range of 0.01 – 5 % depending on how much the pH needs to be shifted. Here too, a diluted solution is used, added drop by drop with constant stirring and continuous pH measurement. The solution is strongly alkaline (pH above 12), so even a small amount causes a large change.

Suitable for products such as

• Cold-process solid soaps – the primary application, hydroxide forms soap from oils and butters.
• Hot-process soaps – the same principle, the mass is cooked after mixing and the soap is ready for use sooner.
• Rinse-off products with pH adjustment – where an alkaline correction of the water phase is needed.

Sodium hydroxide is intended for rinse-off products. For leave-on preparations that remain on the skin, pH adjustment with sodium hydroxide is not recommended without professional oversight.

Good to know

Correctly calculated soap no longer contains free sodium hydroxide after saponification and curing. That is why cold-process soap bars are left to cure until the reaction is complete and the soap's pH drops. Whether the soap is ready is verified by pH measurement.

The white microbeads pour and weigh accurately. Weigh them just before dissolving and close the packaging tightly immediately after use.

Frequently asked questions