How to Remove Mildew From Stone

Written by april dowling
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How to Remove Mildew From Stone
Mildew can mar a stone bench's aesthetic appeal. (Jupiterimages/ Images)

Whether used for countertops, in showers or outdoors, natural stone adds visual appeal to home interiors and exteriors. Marble, granite and slate's durability also contribute to stone's prevalence in residential applications. Nonetheless, stone is porous and prone to mildew when exposed to damp, warm atmospheres. Stone tiles installed in bath areas and on outdoor patios are particularly susceptible to mildew. Mildew is generally a thin black or white growth on stone surfaces. Quickly remove mildew from stone surfaces to revive their natural beauty.

Skill level:

Things you need

  • Pail
  • Chlorine bleach
  • Long rubber cleaning gloves
  • 2 cleaning rags
  • ½ cup talc powder
  • Container
  • Spatula
  • Cling film
  • Plastic spoon
  • Clean towel

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  1. 1

    Fill a pail with 1 gallon of cool water. Pour 1/2 cup of chlorine bleach into the water. Mix the diluted bleach solution.

  2. 2

    Put on long rubber cleaning gloves to protect your hands from the bleach. Drench a cleaning rag in the diluted bleach solution. Wipe the drenched rag over the stone surface to kill and remove the mildew.

  3. 3

    Inspect the stone for remaining mildew. If white or black spores remain, create a poultice by mixing 1/4 cup of chlorine bleach with 1/2 cup of talc powder in a container.

  4. 4

    Spread a 1/4-inch-thick layer of the homemade poultice over the remaining mildew spores using a spatula. Seal the poultice with cling film and wait 24 hours for the poultice to dry.

  5. 5

    Remove the cling film from the dried poultice. Using a plastic spoon, lightly scrape off the poultice.

  6. 6

    Moisten another rag with water. Wipe the moistened rag across the stone to wash off any poultice residue.

  7. 7

    Dry the stone with a clean towel.

Tips and warnings

  • Substitute liquid ammonia for the chlorine bleach.
  • Mixing bleach and ammonia creates lethal gas.

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