Types of Stains and First Step Cleaning Actions

Cleaning Oil-Based Stains on Stone

Oil-based stone stains include:

  • Grease
  • Tar
  • Cooking Oil
  • Milk
  • Cosmetics

An oil-based stain will darken the stone and normally must be chemically dissolved so the source of the stain can be flushed or rinsed away. Clean gently with a soft, liquid cleanser with bleach OR household detergent OR ammonia OR mineral spirits OR acetone.

Cleaning Organic Stains on Stone

Organic stone stains include:

  • Coffee
  • Tea
  • Fruit
  • Tobacco
  • Paper
  • Food
  • Urine
  • Leaves
  • Bark
  • Bird Droppings

May cause a pinkish-brown stain and may disappear after the source of the stain has been removed. Outdoors, with the sources removed, normal sun and rain action will generally bleach out the stains. Indoors, clean with 12% hydrogen peroxide (hair bleaching strength) and a few drops of ammonia.

Cleaning Metal Stains on Stone

Metal stone stain include:

  • Iron
  • Rust
  • Copper
  • Bronze

Iron or rust stains are orange to brown in color and follow the shape of the staining object such as nails, bolts, screws, cans, flower pots, metal furniture. Copper and bronze stains appear as green or muddy-brown and result from the action of moisture on nearby or embedded bronze, copper or brass items. Metal stains must be removed with a poultice. (See section on Making & Using a Poultice) Deep-seated, rusty stains are extremely difficult to remove and the stone may be permanently stained.

Cleaning Biological Stain on Stone

Example of bilogical stone stains include:

  • Algae
  • Mildew
  • Lichens
  • Moss
  • Fungi

Clean with dilute (1/2 cup in a gallon of water) ammonia OR bleach OR hydrogen peroxide. DO NOT MIX BLEACH AND AMMONIA! THIS COMBINATION CREATES A TOXIC AND LETHAL GAS!

Cleaning Ink Stains on Stone

Ink stone stains also include:

  • Magic marker
  • Pen
  • Ink

Clean with bleach or hydrogen peroxide (light colored stone only!) or lacquer thinner or acetone (dark stones only!)