Hello, in this video we'll be showing you the basic procedures for cleaning a stone grave marker. There are two things to remember. First, it's always exercised personal safety, and the second is to do no harm to the grave marker itself. Stone is a very durable material, however, keep in mind the stone can be affected by pollution and weathering over its lifetime, so exercise caution before proceeding with any treatments. Now, before we get started, let's briefly go over what not to do. We don't want to do anything that will remove or damage the original surface of the stone. We never recommend the use of bleach or other salt-laden cleaners. It is also never advisable to use any strong acids or bases finally we don't want to use any harsh mechanical devices such as sandblasting, high pressure power washers, or power tools, such as grinders or drills equipped with wire brushes. All of these methods can damage the grave marker. Let's look at some damage that has resulted from well intending people cleaning with poor techniques.
Okay, so now that we know what to avoid, let's get started and set down the ground rules for how to proceed in keeping with our do no harm policy. It's important to select the gentlest cleaning method possible to accomplish your tasks. The first thing we need is to select our tools before we proceed with the cleaning instructions. Always locate your nearest water supply it takes a lot of water to properly clean stone. If your cemetery does not have running water that is important to bring barreled or bucket of water to the site with you. Also, it is good to have your selected cleaner in the convenient spray bottle. As for the brushes, you always want to use soft bristle, either a natural or synthetic. The general guideline is that if your brush is safe for cleaning the hood of your car it will work well for historic stone. For chemical cleaning, acceptable products are: non ionic detergents solvents, surfactants, biocides and intermediate water misting. When looking for the right type of cleaning products to use try to find a non ionic urgent or product containing biocide with either a neutral pH or a pH similar to that of the stone in your cleaning. We can learn more about the cleaners by reading the product literature and the material of safety data sheets alright so let's get started in keeping with our do no harm policy. We're going to make some small tests to assure we're not going to damage the stone. We have evaluated the selected cleaners and we like the properties this particular one. For this stone there doesn't appear to be any damage caused by the cleaner and the appearance is satisfactory so we're good to continue. Now, we're going to want to soak the stone before we begin. Stone is a very porous material and will quickly absorb any cleaner that is applied to it. By soaking the stone first, it allows the cleaner to stay on the surface of stone this minimizes the impact of the stone and maximizes the cleaners effects. Once it's wet, we start cleaning from the bottom and slowly work our way up to the top. Starting from the bottom of the stone minimizes streaking and staining. I'm going to want to use small circular motions as we go this helps to get in all of the crevices. Sometimes it's important to switch brushes to meet the situation. On stones with a lot of biological growth or heavy soiling you may need to repeat the cleaning methods more than once. If you are using a cleaner that contains a biocide, keep in mind that the stone will continue to lighten over the next few days. Also, as we said before, we're going to use a lot of water make sure you keep the stone rinsed at all times, and there you have it, these procedures are not only useful for general cleaning but can also be performed before more complicated repairs or conservation work takes place.
Now that we've finished cleaning this headstone, we've allowed it to dry overnight to show that will lighten when it's dry. On this particular grave marker, we've used a biocidal cleaner that will continue to lighten over the next few days. Now that you've watched this video and the basic procedures for cleaning a stone grave marker, remember always exercise personal safety and to do no harm to the marker itself and good luck.