How to Clean Slate Mildew

Fortunately, slate mildew can be cleaned using basic household products.

1. Fill a bucket or basin with warm water and add about 1/2 cup of mild laundry washing detergent.

2. Dip a sponge into the laundry detergent solution and use it to scrub the surface of the slate. Get in and around all the crevices in the slate, paying special attention to any grout between the slate tiles.

3. Rinse the slate with warm water and wipe it with a clean dry cloth. If mildew remains on the slate go to Step 4. If you have removed all the mildew from the slate move ahead to Step 7.

4. Fill a spray bottle one fifth of the way with household bleach, and add warm water until the bottle is full.

5. Spray the bleach solution on the slate and the grout making sure to get any areas of heavy mildew. Allow the solution to sit on the slate for 2 minutes.

6. Scrub the slate with a sponge dipped in warm water. Dry the slate with a clean dry cloth. Repeat this until all the visible mildew is gone from the surface of the slate.

7. Fill a spray bottle three-quarters of the way with white vinegar. Add water until the bottle is full.

8. Spray the vinegar and water solution liberally over the slate and any adjacent grout. There is no need to wipe or rinse after spraying the vinegar. The vinegar is a natural deodorant and disinfectant and will inhibit the future growth of mold and mildew.

Tip

Spot test the bleach solution in an out of the way area of the slate to make sure that it doesn't damage the color of the slate. If it does, use a bleach-free commercial household cleanser in place of the bleach solution.

Warning

Do all cleaning with bleach in a well-ventilated area; try to avoid breathing in the bleach fumes.