How to care for old tiles
- Test any cleaning method or product in an unobtrusive corner first.
- Detailed cleaning is best done by hand.
- Never use wire wool or any hard abrasive. Power-driven abrasives can permanently damage the glaze.
- Do not let the product dry on the tile. Mild, balanced-pH, non-ionic detergents are the recommended type.
You may read that acids harm some glazes and alkalis others. We saw that only in search summaries, not on a page we could open, so we do not state it as fact. When in doubt, use plain water and a soft brush on a hidden spot, and ask a conservator for anything valuable.