Sealant failures: Loss of sealant’s initial adhesion and flexibility, causing it to crack and/or pull away from the surfaces to which it is applied. Possible causes: Use of lower quality sealant. Use of wrong type of sealant for a particular application. Substrate not dry. Remedy: Use a top quality water-based pure acrylic or siliconised acrylic sealant if prolonged contact with water is not anticipated. These sealants are flexible enough to adapt to minor fluctuations in the substrate, stretching in gaps that widen slightly over time. They also adhere to a wide range of interior and exterior building materials, including wood, ceramic tile, concrete, plaster, bare aluminium, brick and plastic. With glass as the substrate siliconised sealants are most suitable. Note: Silicone sealant should not be painted.