Hobbies And Interests

How to Weather Limestone

Limestone is a sedimentary rock that is used in many household surfaces including flooring, furniture, table tops and wall coverings. Limestone is formed at the bottom of bodies of water, both saltwater and freshwater. It is composed of calcium carbonate, or calcite -- CaCO3 -- and depending on the location of where it was formed, it will have different amounts of calcium. One of the flaws in limestone is that it has a low tolerance for acid, allowing it to weather and erode with such common natural occurrences as rain and snow.

Things You'll Need

  • Eye dropper
  • Glass beaker
  • Hydrochloric acid
  • Paper towel
  • Paint
  • Glaze
  • Sea sponge
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Instructions

    • 1

      Allow the limestone to be exposed to the elements. Rain, snow, wind, freezing and thawing will all naturally weather the limestone.

    • 2

      Keep the limestone in an area with a lot of rain. Rainwater tends to have a pH between 4.3 and 5.6, which is slightly acidic. Rain water will seep into the pores of limestone, gradually weathering it and breaking up the ions that form it.

      Acid rain contains nitric and sulfuric acids, which erode countless man-made and natural objects. This type of rain is caused by fossil fuels along with other chemicals and pollutants that are being released into the air. Acid rain will erode limestone faster than normal rain. This is called chemical weathering.

    • 3

      Artificially weather the limestone with chemicals by pouring a diluted hydrochloric acid solution on it, which will cause visible effervescence of the carbonate ions as they break down.

      Using an eye dropper, mix 10 drops of water for each drop of hydrochloric acid in a glass beaker. Drop the solution on the limestone and wipe off with a paper towel. You will notice the rock composition starting to change. Continue dropping the acid until satisfied with the results.

    • 4

      Paint the limestone to give it a "weathered" appearance. On unprotected stone, use a sea sponge to dab paint and glaze on the limestone, giving it an aged patina look. Always use sealer to protect the stone after these effects are achieved.


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