A tool like SXhyf's Hard Bristle Crevice Cleaning Brush can work mold and mildew remover into the tile joints and is also great for getting behind faucets. Use a wider scrub brush to remove hard water ...
Clay masonry samples and testing must be as per Test Methods for Sampling and Testing Brick and Structural clay tile ... grout employed for concrete and clay masonry units should conform to ASTM C 476 ...