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Defoamers Selection for Architectural and Industrial Coatings

The demands for ever-faster production times and application speeds for coatings continue to grow. These pressures intensify an inherent problem with coating formulations -- foam generation!

Today, a number of different types of foam-control agents are employed to combat foam. However, selecting the proper one, its use level and incorporation method for a specific coating or ink formulation can be quite a task. In addition to effective foam control, the compatibility of the anti-foam in the coating formulation must be balanced to avoid any surface defects as well.

Review factors that are vital while selecting anti-foaming agents for your architectural and industrial coatings. Also, understand in detail:

    » What is anti-foaming agent or defoamer
    » The various classes of defoamers and their mode of action
    » And, their strengths and limitations per application


We would like to acknowledge Johan Bieleman for providing technical information needed to develop this guide

Foaming Process & Types of Defoamers


TAGS:   Architectural Coatings     Industrial Coatings      Defoamers/Anti-foaming Agents    

Defoamers/Anti-foaming Agents Selection for Coatings Foam is a stable dispersion of a gas in a liquid medium that results when a surfactant layer forms around air bubbles and entrains them within it. Air can be incorporated into a coating:

  • By mixing during the polymer/pigment grinding and let-down steps, 
  • By pumping during package filling or 
  • By shear or spraying during application

In industrial coatings, defoamers are needed in waterborne (WB) as well as solvent borne (SB) industrial paints.

  • In case of waterborne, defoamers play major role during manufacturing as well as application
  • For solvent borne, they are primarily used to avoid foaming during application as well as craters & foamy appearance in the dried film

While, in Architectural Coatings, use of defoamers is mainly needed in waterborne systems, only by exception in solvent-borne systems.

Dispersion paints, such as wall paints, is the largest segment. Defoamers are needed to avoid foam formation during manufacturing as well as application. Waterborne paints tend to stabilize foam, mainly due to the presence of surfactants and wetting agents.

Effective foam-control agents are beneficial in preventing or reducing many common coating problems

These include:

  • Viscosity increase and loss of mechanical shearing power during milling (resulting in smaller batch sizes and poor pigment/polymer dispersion);
  • Volume increase during the letdown and mixing steps leading to overflowing;
  • Slower package-filling rates due to inefficient pumping;
  • Air incorporation during transport and handling;
  • Slower printing-press speeds or lower pressures during spraying;
  • Surface defects on coated substrates resulting in poor appearance, reduction in gloss or less substrate protection.

Stable foams occur when surfactants are present, forming an interfacial layer around air bubbles that are entrained in the coating medium. Also, the dispersing and mixing stages during manufacture cause entrapment of air. If the physical and chemical conditions that cause foam cannot be altered, the addition of foam-preventing or foam-destroying agents is the best option available to the formulator.

» View All Commercially Available Defoaming Agents Grades & Suppliers in Coatings Database

This coatings database is available to all, free of charge. You can filter down your options by suitable resin, system or application (coatings, inks...), supplier and regional availability.

Continue reading to understand how defoaming agents work or click on specific section to understand different criteria for selecting the best suitable defoamer for your application:

  » Foam-Destabilization Mechanisms - How defoamers work?
  » Architectural Coatings - Select suitable defoamer for paints, varnishes etc.
  » Selecting suitable anti-foam agent for Industrial Coatings (based on function, system, substrate...)
  » Silicone Defoaming Agents for Waterborne Coatings


Foam-Destabilization Mechanisms


Foam-control agents can be classified as antifoams or defoamers. Although the two terms are often used interchangeably, strictly speaking, antifoams prevent the formation of stable foams, while defoamers act by destabilizing already existing foams. Foam-control agents function by a variety of mechanisms to prevent or rupture foam. Individual antifoam efficiency is determined by three key factors:

  • Insolubility of the antifoam agent in the foaming medium;
  • Low surface tension, so that it can be uniformly dispersed throughout the formulation;
  • Ability to penetrate into the foam wall (or lamellae).

Uncover Set of
Do’s and Don’ts to Tackle
Foam Issues in Coatings
Tackling Foam Issues
Foam-control agents or defoamers must be insoluble in the foaming medium. They function by being more surface active than the surfactant stabilizing the foam so that they are able to enter the surface layers of the potentially foaming liquid and displace it from the gas/liquid interface.

The mixed surfactant layers now prevent close association of molecules and exhibit low elasticity. The presence of random, highly surface active, insoluble molecules in the surface film interrupts foam stabilization via the Marangoni effect, and thus foaming is prevented.

The four basic processes by which antifoams disrupt aqueous foam are:

  • Entering
  • Bridging
  • Dewetting and 
  • Rupture 

This mechanism proposes that droplets of the antifoam move to the foam lamellae where they provide a point source for rupture of first one air/water interface and then the other. An oil lens is then formed, which bridges the air-water-air foam film. Drainage in the oil lens and foam film takes place until eventually the film ruptures.

Higher bulk viscosity systems, such as formulations containing thickeners or high binder content, slow down the displacement of the liquid from the lamella and limit the mobility of the entrained air bubbles.


Select Defoamers for Architectural Coatings


There are several types of defoamers currently used in architectural coatings. Let's check out their benefits and risks in the table below:

Defoamer Families Benefits Risks
Oil-based, non dispersible
  • High defoaming efficacy
  • Lowest cost
Needing good incorporation, intercoat adhesion
Oil-based, Silicone based dope, non dispersible High defoaming efficacy
  • Some risk for (intercoat) adhesion
  • Breaking flow curtain
  • Needing good incorporation, intercoat adhesion
Easy dispersible, oil, Silicone based defoamer
  • Easy incorporation
  • Good film properties
Low risk for intercoat adhesion failure
Easy dispersible, oil-free, Si based defoamer
  • Easy incorporation
  • Good film properties
  • Meeting oil-free regulation
  • Low risk for intercoat adhesion failure
  • Low risk for haziness
High Silicone content, oil free Excellent binder compatibility, for best film appearance
Oil-free, Non-silicone defoamer, non dispersible Best adhesion
  • Risk for poor film appearance
  • Risk for loosing efficacy during storage
Wax-, Si-, and oil free, dispersible
  • Best adhesion
  • Film appearance
  • Modest defoaming efficiency
Risk for loosing efficacy during storage

One of the main aspect of selecting the right defoaming agent for architectural coating applications is based on according to the application mode for a typical class of coating, like:


Select Defoamers for Flat or Matt wall paints


In most of the cases, paints used for flat / matt wall applications are high PVC dispersion paints (PVC from approx 60 to 85), with the risk of foam formation leading to opacity issues. In flat / matt wall paints, the choice of the right defoamer is cost sensitive.

Type of Flat/Matt Wall Paint Millbase Let-down Brush and Roller Application Spraying Dipping Flow Coat Industrial
Oil-based, non dispersible goodgoodgoodgoodgood
goodgoodgoodgood
goodgoodgoodgood
goodgoodgood goodgood goodgood goodgood
Oil-based, Si dope, non dispersible goodgoodgoodgoodgood
goodgoodgoodgood
goodgoodgoodgood goodgoodgood good good goodgood
Easy dispersible, oil, Silicone based defoamer goodgoodgood goodgoodgoodgoodgood goodgoodgoodgoodgood goodgoodgoodgoodgood goodgoodgoodgoodgood goodgoodgoodgood goodgoodgoodgood
Easy dispersible, oil-free, Silicone based defoamer goodgoodgood goodgoodgoodgoodgood goodgoodgoodgoodgood goodgoodgoodgoodgood goodgoodgoodgoodgood goodgoodgoodgood goodgoodgoodgood
High Si content, oil free goodgoodgoodgood goodgoodgoodgood
goodgoodgoodgood goodgoodgoodgood goodgoodgoodgoodgood goodgoodgood goodgoodgoodgood
Oil-free, Si- free, non dispersible goodgoodgood goodgoodgood goodgoodgood goodgoodgood goodgoodgood goodgoodgoodgood goodgoodgoodgood
Wax-, Si-, and oil free, dispersible goodgood goodgoodgood goodgoodgood goodgoodgood goodgoodgoodgood goodgoodgoodgoodgood goodgoodgoodgoodgood


Select Defoamers for Satin or Eggshell Paints


Medium to high PVC dispersion paints are commonly used for Satin / Eggshell architectural coatings (around 45 to 60). In Satin / Eggshell paints, foam formation decreases the appearance, including the degree of satin.

Brush and Roller is the main procedure of application for Satin / Eggshell paints. Notably with rolling, there is a high risk of air inclusion making the choice of the right defoamer a critical step.

Type of Satin Paint Millbase Let-down Brush and Roller Application Spraying Dipping Flow Coat Industrial Baked 2-pack
 Oil-based,  non  dispersible goodgoodgood
goodgood
goodgoodgood
good
goodgoodgood
good
goodgood goodgood goodgood goodgoodgood goodgoodgood
good
goodgoodgood
good
 Oil-based,  Si dope,  non  dispersible goodgoodgood
goodgood
goodgoodgood
good
goodgoodgood
good
goodgood good good goodgood goodgood goodgood
 Easy  dispersible,  oil, Si  based goodgoodgood goodgoodgood
goodgood
goodgoodgood
goodgood
goodgoodgood
goodgood
goodgoodgood
good
goodgoodgood
good
goodgoodgood
good
goodgoodgood goodgoodgood
 Easy  dispersible,  oil-free, Si-based goodgoodgood goodgoodgood
goodgood
goodgoodgood
goodgood
goodgoodgood
goodgood
goodgoodgood
goodgood
goodgoodgood
good
goodgoodgood
good
goodgoodgood goodgoodgood
 High Si  content, oil  free goodgoodgood
good
goodgoodgood
good
goodgoodgood goodgoodgood
good
goodgoodgood
good
goodgood goodgoodgood
good
goodgood goodgoodgood
goodgood
 Oil-free, Si-  free, non  dispersible goodgoodgood goodgoodgood goodgoodgood goodgoodgood goodgood goodgood goodgoodgood
good
goodgoodgood
good
goodgood
 Wax-, Si-,  and oil  free,  dispersible goodgood goodgood goodgoodgood goodgoodgood
good
goodgoodgood
good
goodgoodgood
goodgood
goodgoodgood
goodgood
goodgoodgood
goodgood
goodgoodgood
goodgood

Select Defoamers for Semi Gloss Dispersion Paints


Main paints used for semi-gloss applications are exhibiting low to medium PVC (30 to 45). In semi-gloss paint applications, formation of foam affects film appearance, but also gloss level.

Type of Semi Gloss Paint Millbase Let-down Brush and Roller Application Spraying Dipping Flow Coat Industrial Baked 2-pack
 Oil-based,  non  dispersible goodgoodgood
goodgood
goodgood  goodgoodgood goodgood goodgood goodgood goodgood goodgood goodgood
 Oil-based,  Si dope,  non  dispersible goodgoodgood
goodgood
goodgood goodgood good good good goodgood goodgood goodgood
 Easy  dispersible,  oil, Si  based goodgoodgood goodgoodgood
goodgood
goodgoodgood
goodgood
goodgoodgood
goodgood
goodgoodgood
goodgood
goodgoodgood
good
goodgoodgood
good
goodgoodgood goodgoodgood
 High Si  content, oil  free goodgoodgood
good
goodgoodgood
good
goodgoodgood
good
goodgoodgood goodgoodgood
good
good
goodgood goodgoodgood
good
goodgoodgood goodgoodgood
goodgood
 Oil-free, Si-  free, non  dispersible goodgoodgood goodgoodgood
good
goodgoodgood
good
goodgoodgood goodgoodgood
good
goodgood goodgoodgood
good
goodgoodgood
good
goodgood
 Wax-, Si-,  and oil  free,  dispersible goodgoodgood goodgoodgood
good
goodgoodgood
good
goodgoodgood
good
goodgoodgood
good
goodgoodgood
goodgood
goodgoodgood
goodgood
goodgoodgood
goodgood
goodgoodgood
goodgood

Select Defoamers for High Gloss Paints

Typical paints used for high-gloss architectural applications are low PVC dispersions. In high gloss paints, surface disturbances resulting of foam formation are easy visible. This is thus critical to select the right defoamer in order to maintain constant gloss level.

Type of High Gloss Paint Millbase Let-down Brush and Roller Application Spraying Dipping Flow Coat Industrial Baked 2-pack
 Oil-based,  non  dispersible goodgoodgood
good
goodgood goodgoodgood goodgood goodgood goodgood goodgood goodgood goodgood
 Oil-based,  Si dope,  non  dispersible goodgoodgood
good
goodgood goodgood good good good goodgood goodgood goodgood
 Easy  dispersible,  oil, Si based goodgoodgood
goodgood
goodgoodgood
good
goodgoodgood
goodgood
goodgoodgood
goodgood
goodgoodgood
goodgood
goodgoodgood
good
goodgoodgood
good
goodgoodgood goodgoodgood
 High Si  content, oil  free goodgood goodgoodgood
good
good
goodgoodgood
goodgood
goodgoodgood
good
good
goodgoodgood
good
good
goodgood goodgoodgood
good
goodgoodgood goodgoodgood
goodgood
 Oil-free, Si-  free, non  dispersible goodgoodgood goodgoodgood
good
goodgoodgood
good
goodgoodgood goodgoodgood
good
goodgood goodgoodgood
good
goodgoodgood
good
goodgood
 Wax-, Si-,  and oil  free,  dispersible goodgoodgood goodgoodgood
good
goodgoodgood
good
goodgoodgood
good
goodgoodgood
good
goodgoodgood
goodgood
goodgoodgood
good
goodgoodgood
good
goodgoodgood
good

Select Defoamers in Clear Varnishes


In unpigmented clear varnishes architectural applications, main binders used may be dispersion or clear solution. Foam formation can affect transparency in the liquid varnish as well as in the dry film, hence the need for careful monitoring.

The highest risk in clear varnishes formulation is micro-foaming: in such cases, defoamer with de-aeration features and easily dispersible will be the best solution.

Type of Clear Varnish Let-down Brush and Roller Application Spraying Dipping Flow Coat Industrial Baked 2-pack
 Oil-based,  non  dispersible good good good good good good good good
 Oil-based,  Si dope,  non  dispersible good good good good good good good good
 Easy  dispersible,  oil, Si based goodgoodgood
good
goodgoodgood
goodgood
goodgoodgood
goodgood
goodgoodgood
goodgood
goodgoodgood
good
goodgoodgood
good
goodgoodgood goodgoodgood
 High Si  content, oil  free goodgoodgood
good
good
goodgoodgood
good
good
goodgoodgood
good
good
goodgoodgood
good
good
goodgood goodgoodgood
goodgood
goodgoodgood goodgoodgood
goodgood
 Oil-free, Si-  free, non  dispersible goodgoodgood
good
goodgoodgood
good
goodgoodgood goodgoodgood
good
goodgood goodgoodgood
good
goodgoodgood
good
goodgood
 Wax-, Si-,  and oil  free,  dispersible goodgoodgood
good
goodgoodgood
good
goodgoodgood
good
goodgoodgood
goodgood
goodgoodgood
goodgood
goodgoodgood
goodgood
goodgoodgood
goodgood
goodgoodgood
goodgood

Select Defoamers for Pigment Dispersions


Typical binders used for pigmented architectural applications are concentrated dispersions of pigments/ extenders in binder-free liquid.

The key to formulate successfully is to avoid effect of pigment dispersion in aqueous medium, usually binder free. When selecting a defoamer for pigment dispersion applications, there is a high risk of loosing defoaming action due to adsorption of defoamer onto pigment, hence the criticity of the choice.

Type of Pigment Dispersion Millbase Let-down
 Oil-based, non dispersible goodgoodgoodgoodgood goodgoodgood
 Oil-based, Si dope, non  dispersible goodgoodgoodgoodgood goodgoodgood
 Easy dispersible, oil, Si based goodgoodgoodgood goodgoodgoodgoodgood
 High Si content, oil free goodgoodgoodgoodgood goodgoodgoodgood
 Oil-free, Non-silicone defoamer, non dispersible goodgoodgood goodgood
 Wax-, Si-, and oil free,  dispersible goodgoodgood goodgoodgoodgood


Solving Foam Issues with Optimal Defoamers Selection


Select Defoamers for Industrial Coatings


Let’s have a quick overview on various types of defoamers used in industrial coatings, highlighting their risks and benefits:

Defoamer Families Key Benefits Risks
Oil-based (Non-dispersible) High defoaming efficacy
  • Needing good incorporation
  • Some risk for intercoat adhesion
  • Breaking flow curtain
Silicone-based Defoamers
(Easy Dispersible, Oil-free)
  • Easy incorporation
  • Good film properties
  • Meeting oil-free regulation
  • Low risk for intercoat adhesion failure
  • Low risk for haziness
High Si Content (Oil-free) Excellent binder compatibility for best film appearance
Wax- & Silicone-based Defoamers
(Oil-free, Dispersible)
  • Best adhesion
  • Film appearance
  • Modest defoaming efficiency
Risk for loosing efficacy during storage
Polyolefins Compound
  • Excellent film surface characteristics
  • Recoatability
Limited efficacy against micro foaming
Polysiloxane
  • Excellent de-aeration, also usually also vs microfoam
  • Best balance between compatibility and incompatibility (=defoaming activity)
May give some risk of adhesion failure and/ or recoatibility
Compounded Defoamers Often compounds of polyacrylates, with siloxanes, and/ or fluor-derivatives for lowest surface tension

Explore key factors to select defoamers/anti-foaming agents for industrial coatings applications according to:



Select Defoamers According to Coatings Function


Primers - Adhesion onto substrate is the key factor to be considered in order to avoid foam formation when formulating primers for waterborne, solvent borne or solvent-free coatings. Especially, microfoam formation can occur in case of corrosion protection.

Defoamer Families Millbase Let-down
Oil-based (Non-dispersible) good good good good good good good
Silicone-based Defoamers
(Easy Dispersible, Oil-free)
good good good good good good
High Si Content (Oil-free) good good good good good good good good good
Wax- & Si-based Defoamers
(Oil-free, Dispersible)
good good good good good good
Polyolefins Compound good good good good good good
Polysiloxane good good good good good good good good good good
Compounded Defoamers good good good good good good good


Protective Coatings - Like for Primers, the selection of the most appropriate defoamer for protective coatings applications will mainly depend on how the defoamer affects adhesion onto substrate and how it can help overcome microfoaming formation.

Defoamer Families Millbase Let-down
Oil-based (Non-dispersible) good good good good good good good
Silicone-based Defoamers
(Easy Dispersible, Oil-free)
good good good good good good good
High Si Content (Oil-free) good good good good good good good good good good
Wax- & Si-based Defoamers
(Oil-free, Dispersible)
good good good good good good
Polyolefins Compound good good good good good good
Polysiloxane good good good good good good good good good good
Compounded Defoamers good good good good good good good


Repair Coatings - In repair finishes coatings, various binder systems can be used. They are mainly applied by spray application leading to air inclusion risks and microfoaming formation. Hence, the need for persistant defoamer is critical.

Defoamer Families Millbase Let-down
Oil-based (Non-dispersible) good good good good
Silicone-based Defoamers
(Easy Dispersible, Oil-free)
good good good good good good good
High Si Content (Oil-free) good good good good good good good good good
Wax- & Si-based Defoamers
(Oil-free, Dispersible)
good good good good good good
Polyolefins Compound good good good good good good
Polysiloxane good good good good good good good good good good
Compounded Defoamers good good good good good good good


Topcoats - Topcoat applications is one of the largest group in industrial coatings, with wide options for resin selection. Critical factors for defoamers selection are include their effect on:
  • Film properties
  • Cratering
  • Pinholes
  • Levelling

Defoamer Families Millbase Let-down
Oil-based (Non-dispersible) good good good good good
Silicone-based Defoamers
(Easy Dispersible, Oil-free)
good good good good good good good good
High Si Content (Oil-free) good good good good good good good good good
Wax- & Si-based Defoamers
(Oil-free, Dispersible)
good good good good good good good
Polyolefins Compound good good good good good good good
Polysiloxane good good good good good good good good good
Compounded Defoamers good good good good good good good



Select Defoamers According to Your Coatings System


2 Component Coatings - In case of two component industrial coatings applications (2K) presence of reactive groups, such as OH could reduce mechanical film properties. The main procedure of application for this segment is brush / roller, notably with rolling high risk of air inclusion. The choice of the right defoamer must take these challenges into consideration.

Defoamer Families Millbase Let-down
Oil-based (Non-dispersible) good good
Silicone-based Defoamers
(Easy Dispersible, Oil-free)
good good good good good good
High Si Content (Oil-free) good good good good good good good good good
Wax- & Si-based Defoamers
(Oil-free, Dispersible)
good good good good good good
Polyolefins Compound good good good good good good
Polysiloxane good good good good good good good good good
Compounded Defoamers good good good good good good good


Baking Finishes Industrial Coatings - For these coatings, temperature stability is key criterium. Polyethersiloxanes are more critical for this than polyestersiloxanes. The most recommended defoamers are Wax-, Si-, and oil free, dispersible for low risk of adhesion failure.

Defoamer Families Millbase Let-down
Oil-based (Non-dispersible) good good good good good good good
Silicone-based Defoamers
(Easy Dispersible, Oil-free)
good good good good good good good
High Si Content (Oil-free) good good good good good good good good good
Wax- & Si-based Defoamers
(Oil-free, Dispersible)
good good good good good good
Polyolefins Compound good good good good good good
Polysiloxane good good good good good good good good good good
Compounded Defoamers good good good good good good good


UV Curable Coatings - In UV curable coatings, the main binders used are based on Acrylates and PE. One of the characteristics of UV Curable paints and coatings is that they contain low or no solvents. Selecting the right defoamer will be mainly a question of:

  • Compatibility with the binder system
  • Overcoming the risk linked to de-aeration effect

Defoamer Families Millbase Let-down
Oil-based (Non-dispersible) good good
Silicone-based Defoamers
(Easy Dispersible, Oil-free)
good good good
High Si Content (Oil-free) good good good good good good good good
Wax- & Si-based Defoamers
(Oil-free, Dispersible)
good good good good good good good
Polyolefins Compound good good good
Polysiloxane good good good good good good good good good good
Compounded Defoamers good good good good good good good

» Find Suitable Defoaming Agent for Your UV Curable Coatings System

Select Defoamers According to Your Substrate


Wood Coatings - Wood coatings refer to a large variation in term of binders systems. The risk of foam formation is mainly linked to inclusion of (micro) bubbles due to slow substrate wetting. Critical factors for selection would be to avoid microfoaming formation.

Defoamer Families Millbase Let-down
Oil-based (Non-dispersible) good good good good good good good
Silicone-based Defoamers
(Easy Dispersible, Oil-free)
good good good good good good good
High Si Content (Oil-free) good good good good good good good good
Wax- & Si-based Defoamers
(Oil-free, Dispersible)
good good good good good good
Polyolefins Compound good good good good good good
Polysiloxane good good good good good good good good good good
Compounded Defoamers good good good good good good

» Select Right Defoamer for Wood & Furniture Coatings

lable Defoamers for Coil Coatings Floor Finishes - Main examples of flooring coatings are Epoxy (EP) and Polyurethane (PUR) floorings, which can be solvent borne, waterborne or solvent-free.

Roller application being the main procedure of application, there is a strong risk of air inclusion, affecting appearance of final flooring coating. Another risk is microfoam formation issue due to film thickness.

Defoamer Families Millbase Let-down
Oil-based (Non-dispersible) good good good good good
Silicone-based Defoamers
(Easy Dispersible, Oil-free)
good good good good good good good
High Si Content (Oil-free) good good good good good good good good good
Wax- & Si-based Defoamers
(Oil-free, Dispersible)
good good good good good good good
Polyolefins Compound good good good good good
Polysiloxane good good good good good good good good good
Compounded Defoamers good good good good good good good


OEM Coatings – They can be base coat or clear coat, with a high risk of microfoaming, whatever the binder system is (various binders systems can be used in OEM Coatings applications). Selecting the right defoamer system will avoid unwanted side effects.

Defoamer Families Millbase Let-down
Oil-based (Non-dispersible) good good good good good
Silicone-based Defoamers
(Easy Dispersible, Oil-free)
good good good good good good good
High Si Content (Oil-free) good good good good good good good good good
Wax- & Si-based Defoamers
(Oil-free, Dispersible)
good good good good good good good
Polyolefins Compound good good good good good
Polysiloxane good good good good good good good good good
Compounded Defoamers good good good good good good good


Can Coatings - In can coatings, EP and PE systems are the most used binders. In case of direct food contact, the required approval defoamer must be selected.

Defoamer Families Millbase Let-down
Oil-based (Non-dispersible) good good
Silicone-based Defoamers
(Easy Dispersible, Oil-free)
good good good
High Si Content (Oil-free) good good good good good good good good good
Wax- & Si-based Defoamers
(Oil-free, Dispersible)
good good good good good good good good good
Polyolefins Compound good good good
Polysiloxane good good good good good good good good good
Compounded Defoamers good good good good good good good good


Coil Coatings - Coil coatings are generally cured at high temperature. Critical criteria of defoamer selection are:
  • Effect on MEK resistance
  • Effect on adhesion
  • Temperature stability

Defoamer Families Millbase Let-down
Oil-based (Non-dispersible) good good
Silicone-based Defoamers
(Easy Dispersible, Oil-free)
good good good
High Si Content (Oil-free) good good good good good good good good good
Wax- & Si-based Defoamers
(Oil-free, Dispersible)
good good good good good good
Polyolefins Compound good good good
Polysiloxane good good good good good good good good good good
Compounded Defoamers good good good good good good good good

» Check Out Commercially Available Defoamers for Coil Coatings

Select Defoamers According to Your Application


Dipping Bath Coatings - A wide variation of binder systems can be used in dipping bath industrial coatings. Though they are systems that commonly exhibit low viscosity, leading to risks for creaming and separation. As a result, there is a continuous air incorporation issue: choosing the right defoamer is a key factor of success overcome these issues.

Defoamer Families Millbase Let-down
Oil-based (Non-dispersible) good good good
Silicone-based Defoamers
(Easy Dispersible, Oil-free)
good good good good good good good
High Si Content (Oil-free) good good good good good good
Wax- & Si-based Defoamers
(Oil-free, Dispersible)
good good good good good good good
Polyolefins Compound good good good good good
Polysiloxane good good good good good good good good good
Compounded Defoamers good good good good good good good


Curtain Coatings - Various binders systems are used in curtain coatings applications. Curtain break is the main concern why using defoamers in this application.

Defoamer Families Millbase Let-down
Oil-based (Non-dispersible) good good good good good good
Silicone-based Defoamers
(Easy Dispersible, Oil-free)
good good good good good good good
High Si Content (Oil-free) good good good good good good
Wax- & Si-based Defoamers
(Oil-free, Dispersible)
good good good good good good good good good
Polyolefins Compound good good good good good
Polysiloxane good good good good good good good good
Compounded Defoamers good good good good good good good


Powder Coatings - In powder coatings, there is a vast choice for binder systems. The highest risk of foam formation is linked to air entrapment in the liquid film via powder during melting and / or polymerization stage. Criteria for defoamers selection are mainly:

  • Good temperature stability
  • Compatibility with the binder
  • Ease of incorporation

Defoamer Families Millbase Let-down
Compounded Defoamers good good good good good good


Silicone Defoaming Agents for Waterborne Coatings


The most commonly silicone defoaming agents are based on Polysiloxanes and modified polysiloxanes. Two properties of silicones make them suitable as aqueous foam-control agents are:
  • They are very hydrophobic and, therefore, incompatible with water; and
  • they are also highly surface active, with liquid surface tension values of approximately 20 mN/m 

Both these properties ensure that silicones will migrate to the air/liquid interface of bubbles within a coating.

Silicone-based Systems as Highly Effective Defoaming Agents

They are used particularly frequently in modern waterborne coatings and printing inks where high demands are made on defoaming characteristics and surface finish. The main disadvantage is that PDMS is so insoluble that it is very difficult to disperse in waterborne systems and almost inevitably causes surface defects.

Hence, silicone defoamers are typically emulsified when added to aqueous coating systems using organic or silicone-based surfactants. They assist in delivering the foam-control agent and to help with leveling/wetting of the applied coating. In addition, a hydrophobic particle may be incorporated into the fluid then used or emulsified to assist with antifoam entry and subsequent foam rupture. Blends of PDMS and silica are often referred to as silicone compounds.

However, they can cause problems!

  • They are extremely incompatible with the foaming medium, which makes them difficult to disperse
  • They are also incompatible with the resin binders leading to dewetting of the coating as it dries and leaving defects in the dried films often described as fisheyes, cissing etc. 

Hence, incorporating modified PDMS in the form of silicone-polyether copolymers into the foam-control formulations easily help meet such incompatibility challenges. The copolymers are synthesized from reactive siloxanes and polyethylene/polypropylene glycol ethers.

By varying the hydrophilic/hydrophobic nature of the silicone polyether, these materials can be used in conjunction with PDMS fluids and compounds such as emulsifiers and wetting agent components of an antifoam compound or emulsion. Silicone polyethers have also been formulated with glycols to form easily incorporated dispersions for applications such as architectural paints, but they can also be designed to function as effective antifoams alone. Potential benefits for polymeric silicone polyether used as the sole antifoam in a coating or ink include:

  • 100% active to allow greater formulation flexibility and lower use levels;
  • Self-emulsifying for easier incorporation into aqueous or polar coatings;
  • No hydrophobic particles to separate or cause surface defects;
  • Balances effective foam control and good surface appearance;
  • Stable polymer allows for incorporation under high shear, allowing for use during the pigment/polymer grind step and increases flexibility in addition point selection.

Silicone-based antifoams have progressed markedly since the first use of PDMS fluids in solventborne coatings and inks. Keeping pace with formulation changes and environmental drivers, silicone antifoams have evolved to comprise a variety of delivery systems and polymer types to meet the specific requirements of diverse formulations.

For waterborne coatings and inks, the product offerings have been expanded to include novel silicone polyether-based antifoams that offer effective foam control balanced against ease of incorporation and good coated surface appearance in several coating and ink systems.

There is no "universal" foam-control agent has been developed to date, therefore, before selecting any foam-control agent it should be evaluated in a particular formulation for suitability


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