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How to Seal Outdoor Slate

Lara Webster

Sealing slate helps prevent permanent stains and cracks. When your slate is outdoors and exposed to the elements, sealing may be especially appropriate. Some sealants provide a glossy finish, while others will leave the slate with its natural matte look. Both afford the same protection, so make the choice based simply on the aesthetic you desire. Impregnating sealers penetrate the slate better and provide the best protection for outdoor tiles.

Slate is easily scratched.
  1. Allow the grout on recently set tile to dry for at least a week. Clean the tile with soap and water and allow it to dry completely.

  2. Apply a thin coat of sealer with a roller or brush. Always work in the direction of the tile's grain and do not let the product puddle.

  3. Let the product saturate the tile for 20 to 30 minutes. Wipe off any excess sealant collecting on the surface with a rag. Allow the tile to dry for two hours.

  4. Apply a second thin coat of sealant with a roller or brush. After 30 minutes, wipe the entire surface with a rag dampened in sealant to clean off excess. Allow the slate to dry for two to six hours before resuming foot traffic or placing furniture on it. If you must walk on the tile immediately, place red rosin paper down until the recommended dry time has passed.