Look around the cemetery. You can see history right there in the headstones - thin, curved-top stones that are so weathered you can't see the dates; huge monuments for important town families; and modern stones still in perfect condition with a bed of beautiful flowers. The variety of stones is incredible...and the difference in the stone conditions can be upsetting.
When a headstone is installed, it shines in the sun. The monument company takes care to deeply inscribe both the lettering and any designs. Rain seems to roll off without diminishing the stone's beauty. No dirt or lichen clings to it. Even without flowers new stones are a striking, a testament to the love for the person buried beneath.
Within a few years, though, nature can really take its toll. Grass trimmings and dirt stick to the face, then the rain comes and it ends up pooling in a darkened mess on the base. Fortunately, this is relatively easy to clean off. But you need to be careful about lichen!
Lichen comes in all shapes, colors, and sizes. It is generally not harmful. But it can detract from the look of your loved one's headstone - obscuring dates and decorations. I've found sayings completely hidden until I cleaned off the thick growth!
Lichen can be round, green and flat - you've seen the circles that seem to pop up and grow wider each year. It grows everywhere: rough and smooth surfaces, in the deep crevices of designs. They're almost impossible to scrape off without using a biological cleaner. The pictures above and below show before and after photos of the top of two different headstones.
Lichen can also be gray (or yellow, or orange) and raised, looking almost like a crust or a bark on your stone. It grows on the rough spots of the stone. On most of the newer stones, this means the top and the short vertical sides (any surface where there is no lettering). Some people see this as a natural occurrence and don't mind the look. However, lichen doesn't just sit on top of the stone. It is a plant, so it has roots. It digs tiny footholds into the rough surfaces. After a few years, a brand new stone can look decades old.
If you don't want lichen on your headstone, it is possible to remove it with a little effort. All you need is a safe biological solution (like D/2), a ton of water, and a few manual tools - I use nylon grout brushes and wooden skewer sticks. Nylon brushes are key, as you want to preserve the stone - nothing that touches the stone must be rougher than the stone itself - you don't want to scratch the smooth surfaces.
As you begin, big chunks of organic material come off and you can really see the progress! By the time you're almost through, it's picky work: sometimes I feel like a dentist, using my wooden skewer to scrape off the tiniest piece of lichen inside a carved leaf. Cleaning the stone isn't difficult - you can accomplish it in just a few hours and a few days time. You can do it yourself, but patience is key!
Speaking of patience, a word of caution: be careful with power washers on stone, especially older stone. Sure, they make the process really fast, but the risk is not worth it - if the pressure is too high, you can actually damage the stone. Personally, I only use manual tools. Nylon brushes and wooden skewers can get the toughest material out of your stone, without risking a major chip. It also helps me feel more connected - and taking care of grave sites is a personal task.
I recommend cleaning a headstone once every 5 years, perhaps more if your stone is located under a tree. If you're game, you can clean it yourself, or call a professional grave care provider. Once you clean your stone, you'll wonder why you hadn't thought to have it cleaned years ago!