Cure R curing compound is for concrete, shake-on hardeners, and new concrete toppings. This VOC-compliant, ready-to-use curing agent conforms to ASTM C 309, Type 1, Class B, and local air quality regulations. Providing excellent early curing properties, it begins to naturally deteriorate after 90 days of regular exposure to sunlight and abrasion. L & M Construction Chemicals, Inc. 800-362-3331.