Dyes

A detergent dye is chosen on five criteria: water solubility, stability at the product’s pH, light fastness, risk of staining surfaces and fabrics, and compatibility with ingredients such as oxidisers, enzymes and fragrance. Dishwashing liquids, liquid soaps and liquid laundry detergents are usually coloured with water-soluble dyes. The final choice should always be confirmed by testing in the target formula and packaging.

pH determines whether a dye keeps its shade and does not fade during storage. Some dyes change colour or fade in strongly acidic products such as toilet cleaners and descalers, others in strongly alkaline products such as drain openers and some laundry liquids. For that reason, a dye should be tested at the pH of the finished product, not in plain water, and the colour monitored under accelerated ageing conditions.

The main safeguard is choosing a dye with good light fastness and testing it in the final transparent bottle. A suitable dye level also helps, since very low concentrations lose intensity faster, as can a UV absorber in the formula or packaging. Oxidisers and fragrance components can accelerate colour loss too. Store test samples in daylight and in a light cabinet, and compare them with a control sample kept in the dark.

Staining risk is reduced by choosing a dye with low affinity for fibres and surfaces and by using the lowest concentration that gives the target colour. This matters most in laundry liquids, cleaners for grout, plastics and stone, and concentrates. In practice, run a staining test: leave a drop of product on the fabric or surface, rinse it off after a set time and check whether any colour remains.

Test the dye in the finished formula, not in water: prepare several concentrations, assess shade and clarity, then run stability tests at elevated temperature, under light and at low temperature in the final packaging, alongside a control sample. In parallel, check staining of fabrics and surfaces and any effect on fragrance and viscosity. Compare the results after several weeks before approving the dye for production.

Yes. Many water-soluble dyes used in cosmetics, such as FD&C Blue 1, tartrazine and Allura Red, also work in detergents, dishwashing liquids and liquid soaps, valued for their purity, solubility and wide shade range. Household products have no positive list of permitted colourants as cosmetics do, but the dye must meet REACH and CLP requirements, and its stability must always be confirmed in the specific formula.

In the EU, detergents fall under Regulation (EC) No 648/2004, which covers the biodegradability of surfactants and labelling, including making an ingredient list available. As a component of a mixture, a dye is also subject to REACH and to classification under the CLP Regulation (EC) No 1272/2008, which affects product labelling. That is why an up-to-date safety data sheet and technical data from the supplier are needed when selecting a dye.

Yes. ViaKosmo technologists help select a dye for a specific product, whether a dishwashing liquid, laundry liquid, liquid soap or surface cleaner, taking into account pH, packaging and the target shade. Support covers everything from concept to industrial scale-up. Describe your product in the form on this page, email sales@viakosmo.pl or call +48 88 66 78 955. Deliveries come with a TDS, SDS and batch certificate of analysis.