In specific circumstances, polyurea may indeed develop cracks. This is attributed to the thermoplastic nature of polyurea, similar to numerous protective coatings and liners. When subjected to a sudden or significant temperature fluctuation exceeding 40°F (22°C), polyurea has the potential to become brittle and eventually form cracks.
This cracking usually occurs in two ways – crazing or micro-fracturing. Crazing refers to the formation of small cracks in the surface of the coating due to shrinkage after application. Micro-fracturing involves deeper cracks caused by increased coating stress due to the expansion or contraction of substrate materials beneath it.
The best way to prevent polyurea coatings cracking is to prepare carefully before application and properly cure afterward. For example, make sure that all surfaces are clear from dirt, dust, grease, oil stains, etc., before applying the coating, as these can cause adhesion failure, which could lead to cracking down the line. Also, be aware that some substrates are prone to absorption when wetted: if dampness has occurred from snow melt or rainfall, for example, then additional time should be taken for adequate drying before application so as not to risk shrinkage during cure time later on, which could again result in craze cracking over time. Finally, ensure that you follow your manufacturer’s instructions and adhere strictly to their recommended drying times for optimal performance; any deviations here will also strain your polyurea.
