What are Defoamers and Antifoam Agents and How are They Used?

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Defoamers and Antifoam Agents and How are They Used

What are Defoamers and Antifoam Agents and How are They Used?

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Defoamers and Antifoam Agents and How are They Used

Foam is simply described as air bubbles trapped in a liquid or solid. In most cases, foam is seen as something positive. For example, whenever you use soap to wash your hands, the formation of foam is pleasing. In fact, you assume that because of the foam, your hands will be clean after you finish washing them.

However, when applying pesticide spray, the occurrence of foam is often seen as a negative aspect. Why? Because foam in the spray mixture may indicate problems with compatibility of spray mixtures, or may result in poor coverage, or wetting of target pests leading to poor control.

How does foam buildup?

Soaps contain chemicals called foaming agents which function as surfactants that reduce the surface tension of water droplets. When the surface tension of the water droplets is reduced, oils on the surface of the skin can be broken up thus allowing the dirt to be washed away.

When pesticides are applied, a surfactant is usually used to counter the surface tension properties of the spray carrier, water. To keep pesticides properly mixed in water, agitation or continual shaking of the spray tank is necessary. This could lead to buildup of foam.

Another way that foam can buildup within the spray tank is when two incompatible chemicals are mixed together. Pesticide incompatibility can cost you time and effort while you clean out the pesticide sprayer.

Is the formation of foam ever beneficial?

As previously mentioned, surfactants can create foam. Therefore, use a foaming agent to create foam if you desire the following benefits:

  1. Enhanced herbicide action, 
  2. Reduced drift, or
  3. Marking the edge of the spray swath to aid the applicator in ensuring there are no overlaps or skips during spraying.

Foam formation is an unavoidable part in several technological processes. The extensive formation of foam might cause serious problems so special additives called defoaming agents or defoamers are used to subdue the formation of foam or eliminate the foam formed.

What is a defoamer?

Defoamers are often used to reduce detrimental foaming of emulsions. Foaming can be disruptive for handling and storage purposes and can also affect the application properties of the pesticide spray mixture. 

Often used when excessive foam is produced by the spray mixture, the terms defoamer and ant-foam agent are used interchangeably. However, there is a difference between a defoamer and anti-foam agent.

Defoamer vs anti-foam agent

The key difference between defoamer and anti-foam is that anti-foam agents can prevent foam from forming, whereas defoamers can control the amount of existing foam. Therefore, anti-foam agents prevent foam formation while defoamers reduce existing foam.

Foam suppressant

  • A foam suppressant is a defoamer that is designed to quickly defoam spray solutions containing nonionic surfactants, silicone surfactants or crop oil concentrates.

How do defoamers and antifoaming agents work?

A defoamer or an anti-foaming agent is a chemical additive that reduces and hinders the formation of foam in industrial process liquids. The terms anti-foam agent and defoamer are often used interchangeably. Strictly speaking, defoamers eliminate existing foam and anti-foaming agents prevent the formation of further foam.

Types of defoamers

There are two common types of defoamers, silicone based and silicone free, with each type of defoamer being either a liquid or powder formulation.  

  1. Silicone based defoamers
    1. Liquid formulation
      • Has a silicone backbone consisting of hydrophobic silica in silica oil.
      • Chemically inert, thermally stable, low surface tension, and completely soluble in water.
    2. Powder formulation
      • Composed of a silicone antifoam compound.
      • Have excellent defoaming action and are stabile in small concentrations.

  1. Silicone free defoamers 
    1. Liquid formulation

  • Most effective in water based and solvent based systems. 
  • Controls foam regeneration and doesn’t cause discoloration. 

b. Powder formulation

  • Composed of silicone antifoam compounds.
  • Excellent defoaming action and have lasting defoaming power and stability in small concentrations. 

Why are defoamers used in spray tanks?

Defoamers are added into the pesticide spray because that is where foam can be formed. More specifically defoamers are used:

  • When there is the potential for incompatibility between two chemicals, e.g., between a herbicide and fertilizer, that can lead to excessive foaming.
    • In crop protection, it is common practice to mix pesticides and other agrichemicals such as adjuvants, fertilizers, biostimulants, and plant growth regulators.
  • When there is excessive agitation of the contents in the sprayer tank that can sometimes lead to a buildup of foam in the tank.

Foam in the sprayer tank must be addressed before the application of pesticide spray. If not addressed, the foam can affect delivery of pesticide application which leads to reduced efficacy.

When a defoamer is one of the tank mix partners, the order in which it is placed into the tank is important.  

Read the pesticide label

Always read and follow product label directions on how to handle foaming. 

Additional reading

Brewer International has been a leader in land and water chemistry since the 1980’s and for over 40 years has proudly served it’s national and regional distributors. 

Our products are used widely across the United States in agriculture, aquatics, forestry, rights of way, and land management. 

Our customers trust our dedication to quality ingredients, tried and true formulas, and positive outcomes.

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