For decorative-concrete contractors who install stamped concrete finishes, surface crusting is one of the most difficult problems to manage in the field. When it occurs, it can lead to large numbers of surface cracks that compromise the appearance of the decorative finish.
During the imprinting phase, surface-crusting problems manifest themselves as small rows of cracks parallel to the joints of the pattern unit. Thousands of cracks can form during one imprinting operation. And they aren't easy to close up afterwards. Surface crusting can occur on both indoor and outdoor concrete placements and is primarily the result of differing subgrade, concrete, and air temperatures. Sun intensity and wind speed also are contributing factors.