How to Remove Mildew From Granite

Wet the mildewed area with water. The water will wet the mildew and stain to prepare it for removal.

Mix some of the poultice with a bit of water until it is the consistency of peanut butter. Mix enough poultice to cover the mildew.

Spread the poultice onto the mildew so it is 1/4-inch thick. Avoid spreading it on unaffected areas.

Cover the poultice with plastic wrap and seal it to the granite with tape. Use a pin to prick a few holes in it so the poultice can dry. Let the poultice sit until it is dry -- up to 48 hours.

Scrape off the poultice with a plastic scraper. Rinse the area with fresh water and dry with a soft towel.