Check the weather conditions before starting the cleaning. If the stone is already warm, or the weather is set to be very warm and sunny, consider waiting until another day. Granite monuments are best cleaned on cool, shady days when the stone itself is cool; this will prevent water and cleaner from drying too quickly and staining or streaking the surface of the stone.
Check the state of the stone monument itself. If there are cracks or chips, especially in the base of the monument, do not attempt to clean it. Water and cleaner can seep into these faults and cause even more damage. If there is surface damage, fix it yourself or contact a professional stone worker for advice or help with repairs.
Begin by saturating the stone with clean water. A hose or spray bottle will work well to saturate the stone; you can also soak a rag from a bucket and apply the water. Remember, though, that once you dip the rag back into the bucket, the water is no longer pure. Wet the stone thoroughly before applying any cleaning solution, and be sure it remains wet throughout the cleaning process.
Start with plain water and a soft-tipped scrub brush to see how well they work cleaning the stone. Water alone will often be enough to clean simple problems such as grass stains, dirt and bird droppings. Progress to stiffer brush bristles as necessary. Plastic scrapers will also remove surface dirt and grime without damaging the stone.
Add detergent to your water as necessary for cleaning. Non-ionic detergents work best on granite, as the pH or acidity of the cleaner is very low and less likely to damage the stone. Products that include biocides will effectively remove mold, mildew and other organic material from the stone's surface; these are slightly harsher chemicals, but will be required for the tougher, organic stains. These products are available at stone and masonry specialty stores, and also on the Internet through websites such as jahnmortars.com. If you are unsure about your product, consult an expert.
Clean the monument in sections so the cleaner doesn't dry on the surface of the monument. Wear protective gloves and goggles when working with chemical cleaners. Rinse the granite often with clean water to check your progress, and also to make sure that you have not damaged the stone with your brush. Rinsing with clean water will also prevent the cleaner from seeping into the stone or from streaking or staining the surface of the granite.
Thoroughly rinse the monument with clean water when the washing is complete. Wipe the monument down with a mixture of baking soda and water on a soft cloth to remove any remaining chemicals from the surface.
Things You Will Need
- Safety gloves and goggles
- Bucket, spray bottle or hose
- Rag or towel
- Scrub brushes
- Plastic scraper
- Always try to clean with the softest brushes and as few chemicals as possible to avoid damaging the stone. Special cleaners may be needed to remove particular stains. For instance, cleaners with oxalic acid will be most effective in removing rust stains. Try to identify the stains on your monument before choosing a cleaning solution.