August 03, 2022

Why the Installation of Primer is Important for Both New Construction & Restoration of Sealant Applications

In previous blog posts, we have discussed all things sealants. From surface preparation requirements, how to apply sealants into an expansion and control joint, applying at low temperatures to how to identify causes of sealant failure, what to lookout for when painting over sealants, and providing expert advise on airport sealants. Today, we want to talk about why it is important to install primer for both new construction and restoration sealant applications.

Primers are used in sealant application to enhance and strengthen sealant adhesion to porous and nonporous substrates. They are typically applied to help ensure proper joint preparation. When using a primer, you’ll get the adhesion you require, helping you maximize efficiency and productivity. Our Technical Service Department put together the following list of some of the reasons why it is important to use a primer as well as best practices.


  1. Improves the sealant’s adhesion in many situations
  2. Priming is not a substitute for good joint design and sealant application
  3. Laboratory and/or field adhesion testing is required for verification of whether a primer is necessary for proper sealant adhesion
  4. Primers should always be used for horizontal and submerged joint applications
  5. Care must be taken to apply primer only to the surface to be sealed. Most primers stain and are difficult or impossible to remove
  6. Almost all sealants, to achieve adequate adhesion for moving joints, require cement based substrates to be primed
  7. Primers must be installed properly (e.g. use the correct primer, do not apply to thick or to thin, and requires drying or curing time before sealant application)
  8. Whenever possible prime substrates before insertion of the sealant backing
  9. Many sealants perform well without the use of primers, but is it best to consult the primer manufacturer for installation requires
  10. The most current Pecora adhesion and primer guidelines may be found online with a wide variety of building substrates located here:
    1. Silicones: 1. TB 109 Pecora Silicone Construction Sealants Adhesion and Primer Guidelines
    2. Urethanes: 1. TB 110 Pecora Urethane Construction Sealants Adhesion and Primer Guidelines

For more information about our sealants, sealant applications, or questions regarding this blog post, we recommend contacting our Technical Service Department. They can be reached by email at or by phone at (800) 523-6688.


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