Just the Right Amount of Foam

The huge amount of water needed to get rid of foam from hand-washed laundry is a major environmental problem.

Whereas the hydrophilic ends of the surfactant molecules project into the water, the hydrophobic ends extend into the air, resulting in the formation of entrapped air. Within the water, individual surfactant molecules arrange to form small, spherical aggregates – bubbles in other words – with the polar, hydrophilic end directed outward and the hydrophobic end on the inside. This is what we know as soap suds.

Even though the consumer generally associates foam with cleanliness, it does have a disadvantage: too many suds can cause a washing machine to overflow.

Essential Additive

How Silicone Defoamers Work: A defoamer spreads over the entire surface of the foam lamella, causing the surface tension to fall and hence the foam bubble to burst.

As a result, foam-control agents are added to laundry detergents to prevent excessive foaming. Antifoam agents are an indispensable process aid in detergents for washing machines. In 2016, the sector for foam-control agents generated sales of three billion US dollars – with the upward trend intact. The largest gains were seen in emerging markets such as China and India, not to mention Japan and Latin America. Besides water- and oil-based products and polyethylene oxide and polypropylene oxide copolymers, silicones are among the key foam-control technologies with a market share of some 40%.

In large parts of Africa and Asia, water does not come out of a tap in the kitchen, but has to be fetched in buckets from central wells or bodies of flowing water.

WACKER has now developed a foam-control agent that makes it a lot easier to rinse hand-washed laundry and thus significantly reduce water consumption. SILFOAM® SD 9019 is an anhydrous, low-viscosity, silicone-based antifoam agent that results in a fine dispersion in water or other highly polar systems. The remarkable feature of this new foam-control agent is its delayed defoamer technology, which does not immediately begin inhibiting foam formation. Unlike a machine wash, where the foam-control agent prevents the detergent from foaming over from the start, SILFOAM® SD 9019 only takes effect when the pH value of the detergent liquor drops. In hand washing, this is typically the case when the detergent is diluted, i.e. rinsed. Once the defoaming agent starts to work, the foam immediately collapses.

“50% of the world’s population still washes its laundry by hand – a laborious task.”