There expensive coating called 'cermark'. This marking compound costs $100 for a small bottle, and must be diluted with ethanol and applied to metal (not ceramics or stone) before being etched to leave behind a permanent dark black mark. | There expensive coating called 'cermark'. This marking compound costs $100 for a small bottle, and must be diluted with ethanol and applied to metal (not ceramics or stone) before being etched to leave behind a permanent dark black mark. |