How to Identify Causes of Sealant Failure in Restoration Construction


At Pecora, our extensive field experience has shown us there are seven common cause of sealant failure that occur in restoration construction. This list includes aging, incorrect sealant selection, inadequate surface preparation, excessive joint movement, early joint movement during sealant cure cycle, improper sealant application, and substrate incompatibility. For this week’s blog we discuss these causes and some ways to mitigate them.

  1. Aging
    1. Sealant has reached its maximum service life and has become dry, brittle, cracked and/or crazed and shows signs of significant aging.
    2. Unfortunately, there is no way to remediate an aging sealant. The product has reached is maximum service life and needs to be removed and replaced.

  1. Incorrect Sealant for Application
    1. Sealant installed was not appropriate for application due to inadequate performance characteristics. The correct sealant should be identified based on the nature of the sealant failures observed.
    2. Sealant failures observed include cohesive or adhesive failure, pre-mature physical degradation due to adverse environmental or service conditions beyond the capability of the selected sealant.
      1. Adhesive failure refers to failure illustrated by the adhesive pulling away clean from the substrate. Cohesive failure refers to failure within the sealant itself, that is the sealant fails leaving behind sealant on the substrate. In the architectural sealant industry, a sealant is said to have acceptable adhesion if it exhibits cohesive failure when tested according to manufactures specifications. Cohesive failure is also required when conducting field adhesion tests.

 

  1. Inadequate Surface Preparation
    1. Sealant is exhibiting adhesive failure due to dirt, dust, debris, and/or other containments present on joint face at time of sealant application.
    2. Omission of manufacturer’s required sealant primer.

 

  1. Excessive Joint Movement
    1. Actual thermal joint movement has exceeded the designed movement capabilities of the installed joint sealant causing cohesive sealant failures.

  1. Early Joint Movement During Sealant Cure Cycle
    1. Early joint movement caused by extreme temperature swings has occurred during the initial sealant cure cycle and has caused surface wrinkling and/or cracking leading to cohesive sealant failures.

 

  1. Improper Sealant Application
    1. Improper sealant dimensions (width to depth ratio) leading to excessive or insufficient sealant depth.
    2. Sealant was not properly mixed leading to insufficient cure and poor sealant performance (applicable to multi-component sealants only).
    3. Three-sided adhesion due to inappropriate or non-existent sealant backing.
    4. Inadequate sealant tooling causing lack of contact at sealant/substrate interface resulting in adhesive failures or insufficient cure.

  1. Incompatibility
    1. Sealant and substrate incompatible causing an adverse reaction at the sealant/substrate interface.

 

For more information, sealant application recommendations, information on the installation procedures, or product/substrate testing, we urge you to contact our Pecora Corporation Technical Services Group. Our expert team is highly qualified to recommend the proper solution for your project. Our Technical Services staff offers training in product technology and use, provides the technical assistance you require in the planning and implementation of your project. They can be reached by email techservices@pecora.com or by phone (800)-523-6688.

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