![]() Evaporation of volatiles during cure, particularly at higher temperatures, can also form bubbles in the coating film. ![]() Additionally, chemical reactions-both intended and unintended-can form gas within a coating film that may create isolated bubbles. Porous and complex substrates, combined with inadequate wetting, can also lead to foam release into a coating film or the foam can remain trapped between coating and substrate. Poor wetting and deaeration can leave air trapped within particle agglomerates or it can be released as microfoam into the liquid. These sources dominate the concerns of foam generation, but they are not the only ones that must be considered. Mixing, pouring, or agitation of a liquid coating and its physical application using a roller, brush, or spray are the most common ways that foam is generated and remains in the system. FOAM GENERATIONįoam can enter a liquid coating from a wide variety of sources. A variety of commercial foam-control chemistries and their effects on different performance attributes were studied in this epoxy formulation, and the results will be used to provide greater clarity regarding their appropriate use in the troubleshooting of foam and achieving foam control. Results of a comparative screening in a 100% solids epoxy test system will also be discussed. This paper reviews the sources and mechanisms of foam generation, as well as the physical processes of foam release. Outside of waterborne systems, foam can still be a problem, and while the mechanisms of stabilization and control have similarities, the nuances of troubleshooting and overcoming challenges can be very different, particularly in high and 100% solids coating systems. This has led to extensive research in the development and positioning of defoamers and deaerators used to control it. 1,2 The unique nature of water and the variety of foam-stabilizing additives used to formulate waterborne coatings make foam a common issue in these types of formulations. Significant literature exists that discusses the stabilization and disruption of foam in waterborne coatings. ![]() With the wide diversity of coating chemistries, properties, processes, and application methods, foam control often requires careful consideration, modification of processes and formulations, as well as extensive time and resources to conduct the needed testing. Foam is pervasive and proper control of it is a critical aspect of preparing and applying a coating. If foam remains in the coating film after drying and curing, it can lead to visual surface defects and degrade a coating’s durability and its ability to protect the substrate below. During use, foam can disrupt continuous processes, overflow reservoirs, and cause frustration to painters during brush, roll, or spray application. During preparation of a formulation, trapped air can lead to poor mixing, low container-fill weights, and challenges in material incorporation. It can lead to reduction in efficiency and performance through all aspects of the process. Meier, Evonik Corporationįoam is a common problem in liquid coatings. Pauley, Kuo-Tsai Griffin Lai, and Ingrid K. Virginia, Pacific coast of Central and South AmericaĪntarctica, South America, Asia, Astronomerīahamas, Caribbean, Central America, South America ( Colombia and Venezuela)Īzores, Newfoundland (Possible exploration of North America in 1473) Rocky Mountains, California, Oregon, Great Basin West coast of Africa (including the Congo River) Northwest Passage (Canada), Río de la Plata, Paraná River (South America) Southwestern United States, Mexico, Argentina North America, Hawaii, Japan, Korea, China, Vietnam, Singapore, Malaysia, India, Persia, Kurdistan, Turkey, Morocco Northern Pacific Ocean, Bering Strait, Alaska (North America) Greater Syria Mesopotamia Asia Minor Arabia Northeast Passage, Novaya Zemlya, SvalbardĪbu Abdullah Muhammad Ibn Battuta Īfrica, Central Asia, China, Europe, Indian subcontinent, Middle East, Russia, Southeast Asia South Asia, Southeast Asia, Middle East, East African coast South Pole, Antarctica, Northwest PassageĪtlantic Ocean, trans-Atlantic (allegedly) Indian Ocean, Southeast Asia, possibly Australia Brazil, North America Greenland, Elephant Island, Northern Patagonian Icefield, Himalayas He led the first successful expedition to the South Pole in 1911, and eventually also reached the North Pole by air in 1926. Roald Amundsen (1872–1928) was an explorer of the polar regions.
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