Chemistry | Hand dishwashing liquids

In the preparation of hand dishwashing liquids blending of water, surface-active agents, various additives, colorants and fragrances must be controlled to obtain proper cleaning characteristics and shelf stability. Anton Paar’s inline refractometer L-Rix 5100 has proven very successful in measuring the totally dissolved solids of hand dishwashing liquids and thus guarantees an accurate dissolving and blending process.


Hand dishwashing liquids are one of the most important groups of household chemicals. Even with the popularity of automatic dishwashers, a great deal of dishwashing is still performed manually. Especially items that are stubborn to clean are mostly washed by hand rather than in a dishwasher.

Formulating hand dishwashing liquids is both science and art. It requires a balance between product performance, aesthetics, safety and cost, while the customers are looking for effective cleaning, longlasting foam, mildness to skin, convenience in use and pleasant fragrance.

In terms of physics and chemistry, hand dishwashing liquids are aqueous solutions of surface-active agents and various additives including fragrances, preservatives, thickening agents and colorants. The manufacturing processes typically involves dispersive and distributive mixing, dissolution of various components, heat transfer for heating and cooling, pipeline transport, filtration and filling.

An integrated, fully-automated measurement of totally dissolved solids of the hand dishwashing liquid ensures proper dissolving and blending, both crucial for the final quality of the product. Anton Paar offers measurement of totally dissolved solids of the hand dishwashing liquid up to 100 % and up to 120 °C with the highest accuracy and reliability.

During mixing and blending, air is introduced and the arising bubbles can negatively influence the measurement. Because a refractive index measurement is unaffected by the presence of bubbles, an inline refractometer is perfectly suited to measure the dishwashing liquid.

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