how to clean a marble headstoneKnowing how to clean a marble headstone, the one placed to commemorate a special loved one, helps you to continue the care and respect your loved one deserves.

Because marble is a crystalline, metamorphosed limestone, composed primarily of calcite and dolomite, it is more susceptible to erosion and decomposition due to exposure.

This ranges from moisture and salt to hydrocarbons and sulfur dioxide pollution all working against the calcite structure of the marble — any exterior marble can be affected.

Soiling Agents Affecting Marble Headstones

There are several different types of materials that contribute to staining a marble headstone. Each type of stain will respond differently to cleaning. These soiling agents are not exclusive to cemetery headstones and can affect all exterior marble installations. Here are some of the main offenders:

  • AIR POLLUTION, such as dirt from vehicle exhaust, can transfer to the surface of the marble. Local production facilities or industrial plants can create added pollutants leaving a crust-like residue resulting in a gray, rough stone surface.
  • BIOLOGICAL CONTAMINANTS like mold, mildew and algae can stick to marble affecting its appearance. These organisms can leave a “biofilm” on the stone that includes sugars and proteins more difficult to remove through standard cleaning processes.
  • BIRD DROPPINGS or other animal waste can penetrate porous marble leaving yellow staining.
  • TREE SAP can leave sticky resins that can be hard to remove and can contain sugars which attract insects as well as promoting the growth of mold and mildew.
  • SALT DAMAGE within the stone itself or in irrigation water or even the ground around the marble headstone can cause disintegration of the marble’s porous surface.

How to Clean a Marble Headstone

how to clean exterior marbleIn knowing how to clean a marble headstone properly you adopt the gentlest, least invasive practices to preserve the longevity of the stone. This is the opposite of an all-to-common assumption that extreme measures, given the contaminants, should be used on exterior marble cleaning.

Because marble is a network of interlocking grains of carbonate materials these grains can become loosened through aggressive cleaning. As these grains are lost over time, the surface of the marble headstone may take on a sugary-looking appearance.

As the surface roughens, it provides more opportunity for soiling agents to stick to it. This is why gentle cleaning, for any exterior marble installation makes all the difference in preserving this natural stone.

Here are the Don’ts for Exterior Marble Cleaning

  • NEVER use wire brushes or power tools such as sanders or grinders to clean the surface
  • NEVER employ harsh, aggressive scrubbing methods when cleaning and overcleaning should be avoided
  • NEVER use household bleach or bleach-containing products. AVOID products that contain the chemicals sodium hypochlorite (NaClO), sodium perborate, sodium percarbonate, sodium persulfate, tetrasodium pyrophosphate, calcium hypochlorite or urea peroxide. These chemicals will create a reaction causing the marble headstone to degrade. Check the MSDS sheets for product ingredients.
  • AVOID using muriatic acid, hydrochloric acid or other strong acids as these will dissolve the marble surface.

Here are the Do’s for Cleaning Exterior Marble

  • Minimize the number of times a cemetery headstone is cleaned in its lifetime — consider a plan to clean once a year.
  • Always test a cleaner on a dry section of marble before using it on the entire headstone. Let the area dry after cleaning to determine its effectiveness. If you are using a cleaner to remove biological stains like mold and mildew, it may take a couple of weeks for it to completely disappear.
  • CAUTION should be exercised if using high pressure washing. Commercial pressure washers generally operate between 750 and 30,000 PSI which can damage the marble’s surface — however, pressure washing at 500 PSI or below and at a distance of 12-inches from the stone face or more is acceptable.
  • Soft bristle brushes with natural or synthetic bristles should be used. Vegetable brushes and soft bristled pet brushes work well for gentle scrubbing.
  • Be sure to locate the cemetery’s water source or bring sufficient water (at least a bucket) since it takes a lot of water to properly clean a marble headstone.
  • As with interior marble cleaning, soak the cemetery headstone with water BEFORE adding a cleaner. An undiluted cleaning agent may leave a residue in the marble’s pores. Wetting the marble first will provide better cleaner spread on the surface and make rinsing easier.
  • Use a circular motion with a soft bristled brush starting from the bottom of a headstone moving to the top. The circular motion creates an agitating effect that loosens any surface soil and that in the marble’s pores.
  • Choose a mild, non-abrasive cleaner, minus the harsh chemicals noted above and be sure the manufacturer’s recommendations for water to cleaner dilution ratio are met. Lastly, rinse, rinse and rinse again to make sure no residue is left behind.