Technical Corner: Flex Seal vs “Flex Seal”

Over the past two months we have seen an increase in calls to our offices regarding purchasing a new product called “Flex Seal”, a product sold in a TV informational.

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Over the past two months we have seen an increase in calls to our offices regarding purchasing a new  product called “Flex Seal”, a product sold in a TV informational.   This relatively new  product is in an aerosol can, and is promoted as a sort of “stop-leak” spray for a variety of applications.

In contrast, our company (CRT) created and developed our product Flex Seal in the 1990s.  Ours is a professional product developed to coat walls, wood, and porous materials such as insulation.  The purpose of  CRT’s Flex Seal is to a) contain and encapsulate fiberglass and similar type particles thought by many to be carcinogens, b) to meet National Fire Protection (NFPA) fire and smoke generation code standards,  c) to provide a very low volatile organic (VOC) contribution, and d) to contain an agent that helps guard against the growth of odors and prevent microbial attack on its coating.
Aerosols generally have high VOC emissions (objectionable odors).   Rubberized compounds also may have a high flammability or smoke generation, making it unsuitable for many uses.

While CRT’s Flex Seal is a flexible coating with qualities listed above, it would be the product of choice for coating insulation within HVAC units or ductwork to seal off the porous insulation, and making it possible to clean the insulation.  Its white color allows users to see immediately if there is any dirt or foreign material buildup on the coating surface, and thus clean it with a rag – something not before possible on porous materials such as insulation.

While the TV infomercial indicates that the aerosol material may be used to seal a condensate pan, this is highly undesirable for several reasons, including VOC emissions, and long term usage.  If one is to coat any surface, it is desirable to clean the surface first or coatings will not have their best adhesion.   In this case, we recommend Pancrete or T-84 to coat these types of surfaces.

Our customer service dept at or our application specialist at can assist you in helping you select the proper products for your application.

Lynn Burkhart is the founder and president of Controlled Release Technologies, Inc. located in Shelby, North Carolina. More information about the company, and its products, can be found at and by calling (800) 766-9057.

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