The area to receive the GUARDIAN CRACK REPAIR SYSTEM™ must be clean and free of any dirt, mildew, chemical residue or the like. The bond of the GUARDIAN CRACK REPAIR SYSTEM™ material to areas that are not clean and free of dirt and debris may be affected. All cracks should be cleaned of any previous crack filling material, dirt, grass, etc, and refilled with a high quality crack filling material per manufacturer’s specifications. The crack filling should be complete, from the bottom of the crack to the top, not back-filled with sand. This crack filling material must be fully cured prior to the installation of the GUARDIAN CRACK REPAIR SYSTEM™. For cracks % of an inch or wider, we recommend filling them with a more substantial filler such as an asphalt cold patch product or a form of concrete patch (hydraulic, etc.). Please note, on wide cracks that experience great movement, there may be some very minor crazing of the acrylic paint. The GUARDIAN CRACK REPAIR SYSTEM™ product will not be cracked or torn; it is simply a function of the acrylic coating I paint product not being capable of expanding and contracting to such excessive degree.