Rock Solid Clean: A Guide To Cleaning Natural Stone In And Around Your Home

Natural stone can be stunning -- whether it is part of a fireplace, a kitchen counter, a wall or outdoors in a pathway or landscape feature. However, natural stone can present some challenges when it's time to clean it. Many cleaning products are too harsh for some types of stone, while others require a stronger cleaner in order to make an impact.

Here are some tips for cleaning natural stone and keeping it clean both indoors and out.

What type of stone are you working with?

You may already know which type of stone you're working with, but it's characteristics will dictate how you clean it. Any natural stone used around a residence is either silica based or calcium based.

Silica:

  • Granite
  • Sandstone and bluestone
  • Slate
  • Gneiss
  • Schist
  • Basalt

Calcium:

  • Limestone
  • Travertine
  • Marble

Silica based stones can be cleaned with acidic or slightly acidic cleaning agents, but calcium based stones can be damaged if you use acid to clean.

Need some help figuring out which is which? Put a tiny drop of muriatic acid (sold at most hardware stores for cleaning purposes) on a hard-to-see part of the stone. Do you see or hear a fizzing sound? You have a sensitive, calcium-based stone. If there's no reaction, it's a silica-based stone.

What kind of stain is on your stone?

Older, stained stone will be easier to clean if you can determine what caused the majority of the stains.

Common sources of stains include:

  • Tire marks
  • Algae or moss
  • Mold or mildew
  • Leaf stains or tree sap
  • Oil stains
  • Hard water deposits

Look for a cleaning product designed to remove these types of stains. Some types of natural stone has patterns that might look like stains, so double check if the type of stone you're cleaning may become naturally discolored.

What types of cleaners should be used?

Outdoor stone areas may be cleanable with a pressure washer. The actual pressure should depend on the type of stone, but a typical household pressure washer with a fan tip and pressure under 1,000 psi should be sufficient for getting stone clean without causing damage. Start in a less visible area and make sure that the pressure you are using is not causing the stone to erode.

Indoor stone may be best cleaned with a product designed exclusively for that type of stone. Remember to avoid any acidic cleaners on limestone, travertine or marble. In many cases, a mild dishwashing soap like Dawn and some elbow grease can get most stains off.

Talk to a professional masonry expert like M Weiss Masonry Inc if you have questions about exactly what types of cleaners are best. You may find that your local mason has a recommended product and process that may help you get the stone clean without spending your own time and energy.


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