HMK® R165 Terracotta Cleaner is a heavy-duty concentrated acid-based cleaning solution formulated to remove grout and cement residue, construction dirt, lime and calcium deposits, and efflorescence from unglazed terracotta, clay tiles, brick, and block paving surfaces. It can also be used on unglazed ceramic and porcelain tiles, concrete blocks, bricks, and other acid-tolerant natural or artificial stone materials. The cleaner is suitable for both interior and exterior applications and can be diluted with water depending on the level of contamination.