Detergency

What is detergency?

Detergency is the cleaning action of a solution: its ability to remove unwanted material, usually called soil, from a surface and to keep that soil in the wash liquid until it is rinsed away. The word describes a performance outcome rather than a single ingredient. In most cleaning products, surfactants do most of the work, supported by other ingredients such as builders, chelating agents, alkalis, solvents and enzymes.

How cleaning works

Removing soil involves several steps, which happen together in practice:

1. Wetting. The cleaning solution has to spread over the surface and into the soil. Surfactants lower the solution’s surface tension so that it can wet greasy or water-repellent surfaces.
2. Loosening oily soil. Surfactant adsorbs at the boundary between the oil and the surface and at the boundary between the oil and the water, lowering interfacial tension. As the solution creeps under the oil, the contact angle of the oil on the surface increases and the film retracts into droplets that detach. This is known as the roll-up mechanism.
3. Removing particles. Surfactant adsorbs on solid particles and on the surface, adding repulsion between them so particles lift away more easily.
4. Holding soil in the wash. Oily soil is held as emulsified droplets or taken up inside micelles by solubilization; particles are kept dispersed. If this fails, soil settles back onto the surface, a problem called soil redeposition.

What affects detergency

A common way to describe the variables is Sinner’s circle, which divides cleaning into four factors that can be traded against one another: chemistry, temperature, mechanical action and time. A weaker chemistry can be compensated by more heat, scrubbing or contact time, and the reverse.

Other conditions matter too:

• Water hardness. Calcium and magnesium ions reduce the effectiveness of many anionic surfactants, which is why builders and chelating agents are added.
• Type of soil. Oily soil, particulate soil, protein and mineral deposits respond to different mechanisms and ingredients.
• The surface. Hard, smooth surfaces clean differently from textiles or porous materials.
• pH. Alkaline conditions help remove fatty and oily soils; acidic conditions help remove mineral scale.

Detergency in industrial cleaning

In industrial and institutional cleaning and degreasing, the soils are often heavy oils, greases, waxes and baked-on residues, and contact time is limited. Formulators balance fast wetting, strong oil removal and good soil suspension against cost, foaming, rinsing and increasingly strict environmental requirements.

Detergency and Locus biosurfactants

Locus supplies its Amphi glycolipid biosurfactants to cleaning formulators as co-surfactants, describing them as improving wetting, soil penetration and soil suspension in heavy-duty cleaning formulations.

Frequently asked questions