Dictionary of Moisture Protection & Restoration

The hourglass system Most manufacturers recommend this system. This hourglass detail allows materials to move properly and enhances the physical properties of the sealant. By maintaining this typical detail, you will avoid cohesive and adhesive failures. Cohesive failure

Sealant material applied too thickly will result in cohesive failure. When the sealant is so thick that it cannot elongate when the substrate is experiencing expansion, it literally rips itself apart, usually in the middle of the joint, when the substrate separates.

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