
You must also take care for protecting the slate tile (it is, however, the main task of any sealant.) For better protection of slate tile, choose penetrating sealers that go deep into the tile as against the topical tile sealers that stay on the surface.
For eco friendly option, you must choose water-based polyurethane sealants that have one of the lowest levels of toxic fumes. It is also non-cracking and non-yellowing that keeps your slate tile look new for years.
For further tips, read How to Seal Slate Tile and Slate Strip