Sandstone coasters are a relatively new product. They are made from naturally absorbent pieces of sandstone. The sandstone is absorbent because its surface has thousands of tiny, microscopic holes that allow moisture to fall down beneath the face of the material. However these holes are so small that the liquid can’t get all of the way through a piece of stone, and so it becomes trapped within the belly of the material, waiting until it can escape by evaporating into the air.
If you overuse a set of sandstone coasters it is possible that they can become saturated. This means that the stone is so soaked through with water that it can’t absorb anymore. However this is quite rare, unless you are using your coasters out in a rainstorm. If it does somehow happen, you can just leave them out in a warm dry place for a few hours and the liquid should evaporate away on its own.
There are actually a couple of different types of sandstone coasters that are available. The original sandstone coasters were simply squares of stone, honed flat, and made from the absorbent material. These were divided into two types, the coasters made from southwestern American sandstone, and those made from imported Asian sandstone.
In general the imported sandstone was more absorbent, but this also made them more prone to stains. The imported materials were also more colorful and varied. Meanwhile the domestic coasters were stronger, and easier to print on, although originally printing destroyed the absorbency of the stone.
Over time a process was developed that allowed manufacturers to print directly on the stone in such a way that it did not interfere with the absorbency of the material. This opened the world up to a whole new collection of sandstone coasters, all in a wide variety of colors, pictures, patterns, and hues.
Today there are literally hundreds of different sandstone coasters available on the market, with almost any image you can imagine printed on them. There are also natural coasters, each with its own unique one of a kind stamp from Mother Nature.