Organizations use defoamers, antifoaming agents, and air release agents as chemical processing aids to minimize or eliminate foam in industrial operations. While the terms are often used interchangeably, they employ different mechanisms, so it is worth distinguishing between them.
Defoamers are foam control agents, which operators add to a system to reduce or eliminate foam after it has been formed.
Antifoaming agents are foam control agents, which operators add to a system or formulation to prevent the appearance or emergence of foam.
Air release agents help remove entrained gases from a solution and raise them to the surface.
These categories are not strictly mutually exclusive. For instance, many chemical formulations both prevent and destroy foam, in which case they could be classified both as antifoaming agents and defoamers. Additionally, many defoamers have some effect on entrained air, while some air release agents initiate the destabilization process for surface foam.
The term “defoamer” is generically used as an industry standard when referencing any processing aid designed to control foam.
What Is Foam?
Foam occurs when a process introduces gas into a system and the gas stabilizes within a solution.
In pure liquids (e.g. water), foam is thermodynamically unstable, and any bubbles will rapidly rise to the surface and burst. Stabilization is only possible in solutions containing additional surface-active components. These components create a surface tension gradient at the gas-liquid interface (the foam lamella, foam film, or bubble wall). The surface tension then allows for much greater foam stability as air is introduced into the solution.
Gravity inherently drains the liquid from foam, which results in the formation of a “dry” polyhedral foam beginning from the top of the foam down. Individual bubbles vary in size and capillary pressure within the foam, so gas naturally diffuses from smaller, higher-pressure bubbles to larger bubbles.
However, as the foam film stretches, the concentration of surface-active ingredients decreases. This decrease in concentration causes a local increase in the surface tension of the foam film, thereby impeding the coalescence of bubbles and stabilizing the foam (Gibbs-Marangoni Effect).
How Do Defoamers Work?
To work well, a defoamer must be partial solubility. A defoamer must be “half-in, half-out.”
If it is too far “in” (i.e. too dispersible or soluble), it will not destroy foam, and may even contribute to additional foam build up. If it is too far “out” (i.e. not dispersible enough or too insoluble in the system), it can cling to equipment, contribute to surface defects or cause other issues. Engineers must intentionally formulate each defoamer formula to achieve the proper level of compatibility.
Additionally, defoamers must have a low surface tension and spread rapidly along the gas-liquid interface, achieving maximum interaction with the foam. As an effective defoamer spreads, it must be capable of displacing the foam-stabilizing surface-active components and penetrating the foam’s lamellae to allow the entrapped gas to escape and the foam to burst.
Chemistry of Defoamers
Which defoamer is most appropriate for a given solution depends on several factors, including:
- The chemical composition and physical properties of the foaming solution
- The method of foam generation
- The type of foam present
Typically, engineers formulate defoamers around a carrier fluid, which may be a hydrocarbon, silicone oil, vegetable oil, synthetic polymer, etc.
Active ingredients, which help with spreading or destabilizing foam, can include waxes, metal salts, silicas, or other hydrophobic particles.
System designers can incorporate an emulsification system to optimize spreading and compatibility of the defoamer to a given foaming system. and depending on the chemistry in the process, designers may add stabilizing agents such as cellulosic or acrylic thickeners to improve shelf stability.
Northstar maintains an extensive portfolio of defoamer chemistries. The following represent some of the broader categories of defoamer and their common uses:
Silicone & Organo-Silicone Defoamers
Silicone & organosilicone defoamers are highly efficient and broadly effective in a wide variety of applications. These products are based on silicone oils (polydimethylsiloxane or modified siloxanes), often with hydrophobic silica dispersed in solution.
Silicone oils have a very low surface tension, which contributes to rapid spreading at the gas-liquid interface and facilitates the weakening of the foam films and penetration of the bubble wall.
Northstar Chemical supplies these types of products as 100% active silicone compounds, dispersions, or as emulsions, which are readily dispersible in aqueous systems.
Non-silicone defoamers can be further broken down into several categories. The most broadly used are mineral oil based due to their optimal performance and lower cost.
Depending on the characteristics, compatibility, and requirements of each foaming system, non-silicone defoamers are also formulated with:
- Vegetable oils
- White oils
- Fatty alcohols
- Synthetic polymers
These defoamers often include hydrophobic particles (e.g. silicas, waxes, etc.) to boost performance. Northstar can supply these defoamers as insoluble or partially soluble dispersions, emulsions or self-emulsifiable, or 100% active liquids.
Within this category, Northstar Chemical also supplies VOC, APE (alkylphenol ethoxylate), and silicone-free defoamers. These products are optimal replacements for traditional mineral-oil-based products used in adhesives, defoamers for paint and coatings, and numerous other applications.
Industrial Applications for Defoamers and Antifoaming Agents
Foam is a significant issue in many material handling and processing operations. If left unchecked, it can reduce processing efficiencies or affect the quality of the products, such as inks, coatings, paints, beverages, wastewater, and textiles, among others. For industry professionals dealing with these issues, Northstar Chemical has the solution.
At Northstar, we carry a broad selection of products—our line of defoamers, antifoaming and air release agents—to suit the various foam control needs of different industrial facilities. These product solutions regularly find application in several distinct applications within the following industries and many more:
- Chemical Compounding
- Food and Beverage
- Inks and Graphic Arts
- Janitorial Supply
- Metal-Working Fluids
- Paints and Coatings
- Paper Products and Paperboard Products
- Wastewater Processes
Which defoamer is most appropriate—including the type and specific formulation—depends on several factors of a particular application. Evaluating which defoamer to select and how to incorporate it can be challenging. Partnering with an experienced foam control expert can streamline the process and facilitate better results in a quicker time.
Contact Northstar Chemical for Quality Defoaming Solutions
At Northstar Chemical, we have extensive experience in the application of defoamers, antifoaming agents, and other foam control products.
Regardless of your application, we have the experience to troubleshoot your foaming problem with one of our proven products or a custom defoaming solution.
Our defoamer line includes:
- Emulsion defoamers
We’ve worked with customers of all sizes to develop a foam control strategy to suit their needs, including developing custom defoamers for wastewater treatment, adhesive defoamers, and other applications. We’d be happy to do the same for you.
Contact our team today to learn more about our product offerings and to get started with your foam control solution.
The defoamers provided by Northstar Chemical meets the following certifications:
FDA, USDA, Kosher, Halal, non-GMO, GRAS, and NSF
For more information, visit our certifications page.