Gravestones will often deteriorate over time due to weathering; however, there are various preservation and cleaning techniques that you can use to help increase longevity and limit the effects of discolouration.
Conservair is a consolidator made by a company named Prosoco. It will penetrate into the surface of gravestones and help re-bond their structure. Most sealants will hold moisture in voids, which can cause expansion and further damage; however, Conservair will fill these voids and prevent moisture from building up. Conservair is only effective for use with sandstone, limestone and marble. For the most effective result, consolidators should be applied to gravestones before they are erected.
There’s a common myth about gravestones that states stone and tile sealer will preserve them. However, these chemicals are not recommended as they can trap moisture and cause adverse effects. Over time gravestones will accumulate deposits from hard water, dust, dirt, mould, lichens and fungus. Before you start to clean anything off it’s important to understand what cleaning methods are suitable for the gravestone. Without any knowledge you could do more harm than good. In addition, you should always check the gravestone to ensure there is no flaking on the surface, and that it’s firmly in the ground.
Limestone and Sandstone
With a hardness of only 3-4 on the Mohs Hardness Scale, limestone and sandstone are among the softest materials used for gravestones. Due to their fragility it’s important to thoroughly assess them for damage before you begin cleaning. To clean, mix a cup of non-ionic soap in a bucket of distilled water and use a natural bristled brush to wipe the surface. Do not use metal wire brushes, acidic cleaners, household cleaners or pressure washers. Doing so could cause the gravestone to crumble.
Marble has a hardness of 4-7 on Mohs Hardness Scale, making it tougher than sandstone and limestone, but not as durable as granite. Although marble is fairly tough, it’s still not a good idea to use a pressure washer To clean, mix a cup of ammonium hydroxideor in a bucket of distilled water and use a natural bristled brush to wipe it over the surface. This will remove any moss, algae and lichen. Rinse off the cleaning solution with distilled water when you have finished.
Granite is the strongest material with a hardness of 7-9 on Mohs Hardness Scale. When cleaning granite, mix a cup of non-ionic soap in a bucket of distilled water and use a non-metallic scouring pad to scrub the surface. This will remove calcium deposits. It’s okay to be a little more aggressive with granite as it’s much stronger than other materials. Feel free to use a pressure washer; however, be wary if the gravestone is coloured. The strength of the water flow could strip off paint in engraved areas, leaving little contrast for the reader.
Because bronze plaques are often mounted into a flat base, they can be more susceptible to weathering. Bronze gravestones usually have a lacquer finish, which if neglected, will deteriorate over time. Unlike other materials, bronze gravestones require waxing after they are cleaned in order to bring out the shine. Start by applying a small amount of water mixed with non-ionic soap to the bronze with a natural bristled brush. After scrubbing off any dirt, rinse the bronze with distilled water. Make sure the bronze is completely dry before you apply the wax. To speed up the process, use a flannel cloth to wipe it down. Apply the wax with a natural bristled brush. Coat the entire surface and then buff the bronze with a flannel cloth to bring out the shine. Do not clean bronze markers too frequently and remember that bronze will natural darken over time.
Slugs and snails can be used to naturally clean gravestones as they actively consume lichens, mould and algae. To utilize this cleaning method, make an artificial greenhouse by covering the gravestone with a polythene sheet. If you leave it for a few days in hot weather it will attract slugs and snails and encourage them to do the hard work for you. Regardless of which cleaning method you use, always wash the gravestone from the bottom up and make sure any bronze plaques or ceramics are covered before you begin. When you finish, make sure the cleaning solution has been completely removed – long term exposure could cause damage. Gravestones do not require cleaning on a regular basis, definitely no more than once per year. In fact, some gravestones should not be cleaned more than once every ten years. In addition, you may need to seek permission from the churchyard or cemetery before you begin as they may have a registered caretaker that will conduct the process on your behalf. If there are deep stains even after you’ve cleaned the gravestone, don’t remove them. You should also not attempt to refinish gravestones yourself.