Flex-Coat Cement - 5 GallonBrutal Rust has developed a flexible hard coat that can be applied like thinset concrete and is flexible enough to protect your set or prop. This stuff is the real deal! One coat of Flex Coat and your prop or set will look like concrete. More than one coat and your prop or set will be protected from dings and scratches. INSTRUCTIONS 1. Flex Coat to water ratio: 1. 5 parts flex coat to 1 part water Start by adding the Flex Coat into your mixing bucket.