Painting & Coating Industry (PCI) logo Powder coating summit logo
  • Sign In
  • Create Account
  • Sign Out
  • My Account
  • NEWS
  • PRODUCTS
  • MATERIALS
  • TECHNOLOGIES
  • FINISHING
  • RESOURCES
  • EVENTS
  • DIRECTORIES
  • EMAGAZINE
  • CONTACT
cart
facebook twitter linkedin youtube
  • NEWS
  • Latest News
  • Market Trends & Reports
  • Price Alerts
  • Subscribe to eNewsletters
  • Global Top 10/ PCI 25
  • Weekly Featured Article
  • COATLE Word Game
  • PRODUCTS
  • Product News
  • Must See Products and Services
  • MATERIALS
  • Additives
  • Resins/Polymers
  • Pigments
  • Equipment
  • Distributors
  • TECHNOLOGIES
  • Adhesives
  • Architectural Coatings
  • Industrial Coatings
  • Nanotechnology
  • Powder Coatings
  • Solventborne
  • Special Purpose Coatings
  • Sustainability
  • UV Coatings
  • Waterborne
  • Waterborne
  • FINISHING
  • Finishing News
  • Finishing Technologies
  • Finishing Equipment
  • RESOURCES
  • Columns
  • Blogs
  • Coatings Supplier Handbook
  • Podcasts and Videos
  • PCI Store
  • eBooks
  • Sponsor Insights
  • White Papers
  • COATLE Word Game
  • Columns
  • Ask Joe Powder
  • Did you know?
  • Distribution Dive
  • Focus on Canada
  • Formulating With Mike
  • Innovation Insights
  • Moody's Coatings Conundrums
  • Powder Coating Perspectives
  • Target the Market
  • TiO2 Insider
  • Blogs
  • Editor's Viewpoint
  • Industry Insights
  • Podcasts and Videos
  • COAT-IT! Podcast
  • Videos/PCI TV
  • EVENTS
  • Coatings Trends & Technologies Summit
  • Paint and Coatings Academy
  • Webinars
  • Calendar of Events
  • Lifetime Achievement Award
  • DIRECTORIES
  • Buyer's Guide
  • Equipment Directory
  • Materials Directory
  • EMAGAZINE
  • Current Issue
  • eMagazine Archive
  • China Issue Archive
  • Editorial Advisory Board
  • CONTACT
  • Contact Us
  • Advertise
  • Subscribe to eMagazine
  • Subscribe to eNewsletters
Painting & Coating Industry (PCI) logo Powder coating summit logo
search
cart
facebook twitter linkedin youtube
  • Sign In
  • Create Account
  • Sign Out
  • My Account
Painting & Coating Industry (PCI) logo Powder coating summit logo
  • NEWS
    • Latest News
    • Market Trends & Reports
    • Price Alerts
    • Subscribe to eNewsletters
    • Global Top 10/ PCI 25
    • Weekly Featured Article
    • COATLE Word Game
  • PRODUCTS
    • Product News
    • Must See Products and Services
  • MATERIALS
    • Additives
    • Resins/Polymers
    • Pigments
    • Equipment
    • Distributors
  • TECHNOLOGIES
    • Adhesives
    • Architectural Coatings
    • Industrial Coatings
    • Nanotechnology
    • Powder Coatings
    • Solventborne
    • Special Purpose Coatings
    • Sustainability
    • UV Coatings
    • Waterborne
    • FINISHING
      • Finishing News
      • Finishing Technologies
      • Finishing Equipment
    • RESOURCES
      • Columns
        • Ask Joe Powder
        • Did you know?
        • Distribution Dive
        • Focus on Canada
        • Formulating With Mike
        • Innovation Insights
        • Moody's Coatings Conundrums
        • Powder Coating Perspectives
        • Target the Market
        • TiO2 Insider
      • Blogs
        • Editor's Viewpoint
        • Industry Insights
      • Coatings Supplier Handbook
      • Podcasts and Videos
        • COAT-IT! Podcast
        • Videos/PCI TV
      • PCI Store
      • eBooks
      • Sponsor Insights
      • White Papers
      • COATLE Word Game
    • EVENTS
      • Coatings Trends & Technologies Summit
      • Paint and Coatings Academy
      • Webinars
      • Calendar of Events
      • Lifetime Achievement Award
    • DIRECTORIES
      • Buyer's Guide
      • Equipment Directory
      • Materials Directory
    • EMAGAZINE
      • Current Issue
      • eMagazine Archive
      • China Issue Archive
      • Editorial Advisory Board
    • CONTACT
      • Contact Us
      • Advertise
      • Subscribe to eMagazine
      • Subscribe to eNewsletters
    Paint and Coatings Additives

    What are Defoamers?

    BASF
    January 3, 2017

    Note: This article originally appeared at http://knowledge.ulprospector.com/5058/pc-defoamers-an-introduction/.

    Defoamers are chemical additives that reduce and/or prevent the formation of foam in industrial process liquids such as paints, inks, adhesives and even construction products. The terms antifoam agent and defoamer are often used interchangeably, however, antifoam agents more accurately refer to materials that inhibit the generation and formation of bubbles. Dependent upon the application and performance requirements, they consist of polydimethylsiloxanes and other silicones, insoluble oils, stearates and glycols, as well as inorganics, such as silicates and talc.

    What is Foam?

    Foam is a coarse dispersion of a gas in a liquid, where the volume fraction of gas is greater than that of the liquid. The bubbles will migrate to the surface, as their density is less than that of the liquid. As the bubbles coalesce and collect at the air/surface interface, the bubble walls thin and break. Defoamers accelerate the process and break the smaller bubbles as well. Generally a defoamer is insoluble in the foaming medium and has surface-active properties. An essential feature of a defoamer is the ability to spread rapidly on foamy surfaces.

    In industrial processes, foams pose serious problems. They cause defects on surface coatings. They prevent the efficient filling of containers. Some of the sources of foam formation include:

    • Inclusion of air through agitation during production, filling, mixing of two-pack systems (often high-viscosity (epoxies, adhesives);
    • Air inclusion on the pigment surface, resulting in poor wetting of pigments;
    • Application: roller, spraying, brushing;
    • Filtration through sieve or anything with air on the surface;
    • Generation/liberation of gases during chemical curing processes; e.g. polyisocyanates;
    • Introduction of air through substrate wetting (wood coatings, other highly porous substrates).

    It is suggested that the following is considered if you require a more thorough understanding of the subject of foam generation, defoamer composition, mechanisms, etc.:

    • Foam stabilization
    • Composition and mode of action of defoamers
    • Test methods
      • Paints
      • Inks
      • Adhesives
      • Construction products
    • Selection guidelines
      • Process
      • Application
    • Coatings defects

    Dissipating Foam

    For this article, the focus will be on the mechanical dissipation of foam as well as the chemical elimination of foam. In the former, there are several effective methods: 1) bubble consolidation is achieved with lower shear mixing, which will put the microfoam in contact, esp. at the surface (vortex), and foam will consolidate to larger bubbles that break more easily; 2) vibration using a rotosieve to reduce the surface tension at the air/liquid interface in processes such as filtration of latexes; 3) utilizing a very fine mist of water spray - the bubble walls will be disrupted and break; 4) vacuum such as a RotoVap or Ross Mill homogenizer and vacuum.

    Chemical defoamers similarly have analogous methods, which are in the form of composition rather than processes: 1) in process, they can either consolidate small foam to larger bubbles, which can then break at the air/liquid interface; and 2) break bubbles during mixing and shear. During application, they: 3) disrupt the bubble wall, or cause increased drainage. In many cases, the choice of a chemical defoamer is a balance between highest efficiency and lowest undesired side effects, coupled with a preferred mechanical process, if available.

    Choosing the Right Defoamer and Test Method

    There are many considerations in the choice of a defoamer. For paints, persistency over a long shelf life is required, but the defoamer (often mineral-oil based) cannot affect color uniformity, such as rub-up. For waterborne flexographic inks, mineral oil is not a consideration as it causes roller and plate swelling. Therefore, the preferred defoamers are based on glycols and polyglycol (ethers). Silicone defoamers are used in solventborne and high-viscosity systems, and are used more in the grind stage of pigment dispersion, rather than in the letdown.

    Choosing the correct test method that includes the appropriate substrate and perseverance upon storage is key. As an example, if formulating a waterborne polyurethane or acrylic urethane, a strong defoamer may be required, since application to a porous wood substrate will liberate microfoam, and the coating surface energy is particularly high. If a film is cast over a sealed paper chart such as a Leneta 2C card, the film may show severe crawling and fisheyes. The conclusion might be that there was an overdose of defoamer. However, testing on a Leneta R1A Birch plywood plank would show a uniform coating void of film defects and bubbles. Heat aging is a quick way to evaluate long-term storage stability, usually done at intervals of one week for a total of four at 50 °C; testing at each week. The other critical test is compatibility to ensure that the defoamer doesn’t interact or react with a component of the coating and cause seeding.

    Conclusion

    In summary, defoamers are essential ingredients in a paint formulation avoiding foam formation and stabilization in waterborne as well as solventborne paints. Proper selection of defoamer quality and quantity is essential for optimal defoamer performance. Defoamers compete with foam-stabilizing ingredients in order to be effective in a coating system. The proper defoaming results in paint quality properties, and it is important that test methodologies are appropriate for the specific application or process.

     

    1 Quantitative Performance Assessment of New Foam Control Agents in Waterborne Coatings, Ashland Specialty Ingredients 3/25/2013.

    2 Axalta Coating System, Paint Defects Manual 9/12/2013.

     

    About Prospector® from UL

    Prospector is a specialized material and ingredient search engine for product developers offered by UL, the world leader in product safety. The Prospector Knowledge Center publishes articles on materials, processes, technical challenges and more from top industry experts. For more information, visit https://www.ulprospector.com.

    By Marc Hirsch, Senior Development Scientist, M&M Hirsch & Associates, LLC, Roanoke, VA. Originally published on the Prospector® website, http://knowledge.ulprospector.com/

    proespector

    KEYWORDS: defoamers

    Share This Story

    Looking for a reprint of this article?
    From high-res PDFs to custom plaques, order your copy today!

    Recommended Content

    JOIN TODAY
    to unlock your recommendations.

    Already have an account? Sign In

    • PCI-0724-Global10-Feature-1440.png

      2024 Global Top 10: Top Paint and Coatings Companies

      Who ranks on top? PCI’s annual ranking of the top 10...
      Global Top 10 and PCI 25
      By: Courtney Bassett
    • PCI-0724-PCI25-Feature-1440.png

      2024 PCI 25: Top Paint and Coatings Companies

      PCI's annual ranking of the top 25 North American paint...
      Paint and Coating Market Reports
      By: Courtney Bassett
    • pci1022-Kinaltek-Lead-1170.jpg

      A Novel Pigment Production Technology

      Following an extensive R&D program that demonstrated...
      Paint and Coating Pigments
      By: Jawad Haidar and Nitin Soni
    You must login or register in order to post a comment.

    Report Abusive Comment

    Manage My Account
    • eMagazine
    • eNewsletter
    • Online Registration
    • Subscription Customer Service

    More Videos

    Sponsored Content

    Sponsored Content is a special paid section where industry companies provide high quality, objective, non-commercial content around topics of interest to the PCI audience. All Sponsored Content is supplied by the advertising company and any opinions expressed in this article are those of the author and not necessarily reflect the views of PCI or its parent company, BNP Media. Interested in participating in our Sponsored Content section? Contact your local rep!

    close
    • Modern arapartment complex painted in bright colors.
      Sponsored byEPS - Engineered Polymer Solutions

      Architectural Polymers Leading the Way in Coatings Innovation

    • paint sprayer in a workshop
      Sponsored byallnex

      Enabling Performance and Compliance: allnex Introduces a New Line of VOC Exempt Solvent-Borne Resins

    Popular Stories

    No. 3 AkzoNobel

    AkzoNobel to Close Two Manufacturing Sites

    Modern living room interior with green plants, sofa and green wall

    Reimagining Architectural Paints with Plant-Based Acrylic Binders

    Modern arapartment complex painted in bright colors.

    Architectural Polymers Leading the Way in Coatings Innovation



    PCI Buyers Guide

    Submit a Request for Proposal (RFP) to suppliers of your choice with details on what you need with a click of a button

    Start your RFP

    Browse our Buyers Guide for manufacturers and distributors of all types of coatings products and much more!

    Find Suppliers

    Events

    September 3, 2025

    Coatings Trends & Technologies Summit

    The Coatings Trends & Technologies (CTT) Summit is an annual conference for both liquid and powder coatings formulators and manufacturers to discuss innovations in coatings technology. This event combines high-quality technical presentations, a resource-rich exhibit hall, and dedicated networking opportunities to connect scientific minds, foster innovation, and cultivate game-changing new ideas!

    January 1, 2030

    Webinar Sponsorship Information

    For webinar sponsorship information, visit www.bnpevents.com/webinars or email webinars@bnpmedia.com.

    View All Submit An Event

    Poll

    Longest-running laboratory experiment

    What is the longest-running laboratory experiment?
    View Results Poll Archive

    Products

    CTT Summit Short Courses (Live 9/3/25)

    Coatings Trends & Technologies Summit is expanding its offerings with four short courses. These short courses will offer an extensive day of interactive learning.

    See More Products
    pci  webinar april 2025

    PCI CASE EBOOK

    Related Articles

    • FINISHING DEFENSE: Film Thickness: Are You Giving Uncle Sam What "We" Paid For?

      See More
    • Viewpoint.jpg

      What Are the Top Technologies, Markets and Drivers?

      See More
    • What Trends Are Impacting Exterior and Interior Architectural Coatings?

      What Trends Are Impacting Exterior and Interior Architectural Coatings?

      See More

    Related Products

    See More Products
    • pci january 2020

      PCI January 2020 Issue

    • Nanocoatings_150x225.gif

      Nanocoatings: Principles and Practice

    See More Products

    Related Directories

    • Enterprise Specialty Products Inc.

      ESP specializes in foam control technology. We supply defoamers and anti-foams for the ink, adhesive, paint and coatings markets.
    • Hydrite

      Hydrite offers a full line of defoamers, antifoams and air-release agents designed to assist with PCIA applications. Our defoamer solutions are formulated for solvent-borne, water-reducible, water-based and 100% active systems. Leverage our vast knowledge and lab support to help resolve defects, satisfy regulatory requirements, custom formulate, and achieve optimal performance.
    • BYK USA

      BYK USA is a leading supplier of specialty additives that are used to optimize production and application processes and visibly improve the qualities of the finished products. Additives range: wax additives, adhesion promoters, wetting and dispersing additives, surface additives, defoamers, rheological additives, surfactants, nanotechnology and more.
    ×

    Keep the info flowing with our eNewsletters!

    Get the latest industry updates tailored your way.

    JOIN TODAY!
    • RESOURCES
      • Advertise
      • Contact Us
      • Directories
      • Store
      • Want More
    • SIGN UP TODAY
      • Create Account
      • eMagazine
      • eNewsletters
      • Customer Service
      • Manage Preferences
    • SERVICES
      • Marketing Services
      • Reprints
      • Market Research
      • List Rental
      • Survey & Sample
    • STAY CONNECTED
      • LinkedIn
      • Facebook
      • Youtube
      • X (Twitter)
    • PRIVACY
      • PRIVACY POLICY
      • TERMS & CONDITIONS
      • DO NOT SELL MY PERSONAL INFORMATION
      • PRIVACY REQUEST
      • ACCESSIBILITY

    Copyright ©2025. All Rights Reserved BNP Media.

    Design, CMS, Hosting & Web Development :: ePublishing

    Painting & Coating Industry (PCI) logo Powder coating summit logo
    search
    cart
    facebook twitter linkedin youtube
    • Sign In
    • Create Account
    • Sign Out
    • My Account
    Painting & Coating Industry (PCI) logo Powder coating summit logo
    • NEWS
      • Latest News
      • Market Trends & Reports
      • Price Alerts
      • Subscribe to eNewsletters
      • Global Top 10/ PCI 25
      • Weekly Featured Article
      • COATLE Word Game
    • PRODUCTS
      • Product News
      • Must See Products and Services
    • MATERIALS
      • Additives
      • Resins/Polymers
      • Pigments
      • Equipment
      • Distributors
    • TECHNOLOGIES
      • Adhesives
      • Architectural Coatings
      • Industrial Coatings
      • Nanotechnology
      • Powder Coatings
      • Solventborne
      • Special Purpose Coatings
      • Sustainability
      • UV Coatings
      • Waterborne
      • FINISHING
        • Finishing News
        • Finishing Technologies
        • Finishing Equipment
      • RESOURCES
        • Columns
          • Ask Joe Powder
          • Did you know?
          • Distribution Dive
          • Focus on Canada
          • Formulating With Mike
          • Innovation Insights
          • Moody's Coatings Conundrums
          • Powder Coating Perspectives
          • Target the Market
          • TiO2 Insider
        • Blogs
          • Editor's Viewpoint
          • Industry Insights
        • Coatings Supplier Handbook
        • Podcasts and Videos
          • COAT-IT! Podcast
          • Videos/PCI TV
        • PCI Store
        • eBooks
        • Sponsor Insights
        • White Papers
        • COATLE Word Game
      • EVENTS
        • Coatings Trends & Technologies Summit
        • Paint and Coatings Academy
        • Webinars
        • Calendar of Events
        • Lifetime Achievement Award
      • DIRECTORIES
        • Buyer's Guide
        • Equipment Directory
        • Materials Directory
      • EMAGAZINE
        • Current Issue
        • eMagazine Archive
        • China Issue Archive
        • Editorial Advisory Board
      • CONTACT
        • Contact Us
        • Advertise
        • Subscribe to eMagazine
        • Subscribe to eNewsletters