Before You Buy Sandstone Coasters
Sandstone is an exotic natural material that is quarried from mountain ranges around the world. Being a type of stone it has a very hard surface, yet this surface is dotted with millions of tiny almost invisible pores. The result of these properties is that when liquid is placed on the surface of sandstone it tends to sink in, becoming trapped within the pores until the air has time to evaporate it away.
This makes sandstone the perfect material for a set of drink coasters. You can put your sweaty glass down on it and the moisture will simply soak into the stone, leaving table surfaces free of nasty water rings.
However this same absorbent property can also be a bit of a liability when considered against the long term maintenance of the product. While water absorbs readily enough into the stone, so do other liquids and some of these contain staining agents that could permanently alter the appearance of the coasters.
Unfortunately the only way to completely protect sandstone from stains is to use a chemical agent to clog its pores, thus eliminating the absorbency, and much of the usefulness of the product.
Clogging these pores is not a complete process; it can be done in gradients allowing the manufacturer of the coaster to choose how absorbent they want the final product to be. If you see the term natural stone coasters used when describing a product there is a chance that the stone has not been treated at all, leaving it fully absorbent. However manufacturers and retailers do vary on what exactly that term means.
There is also a method whereby images can be printed onto the sandstone allowing manufacturers to either blend natural stone with art, or to completely cover up the surface of the stone with an image. In the past this printing process would have created a layer over the stone eliminating its ability to absorb moisture. However today advances in printing technology allow sandstone coasters to be printed with vibrant images that do not completely clog up the pores of the stone. However the process does reduce the absorption of the coasters to some extent, and it also covers up stains that can occur underneath the print.
If you do spill a staining agent on a sandstone coaster that is not protected, you should wash the surface of the stone in warm water immediately. If you catch it quickly enough, you will probably be able to extract the color before it dries in the stone. Running warm water over the coaster can also flush the material out to some extent.
You should never use chemical cleansers or soaps to clean your coasters, as they can react with the stone causing further discoloration.
If a stain does occur, your only recourse is to soak the stone in a vat of warm or very hot water. This may loosen up the stain, and allow it to wash out of the material. The longer you soak the stone the more likely that you will be able to recover its original appearance, however this can cause damage to the cork or felt backing on the piece. Luckily this can be easily enough replaced with materials from the local craft store.
The other problem that you occasionally get with sandstone coasters is chipping. Sandstone is a relatively hard and durable material, and it will have to be hit pretty hard for damage to occur, but a chip is the kind of thing that is almost possible to repair. Your one option is to use sandpaper to apply a bevel along the edge of the stone, thus hiding the chip.
Sandstone beverage coasters are some of the most functional coasters that you can buy to protect your possessions, however that same absorbent property that makes them useful can also be a liability, making them susceptible to stain damage from colored liquids. However with just a little care you can protect the stone from damage and stains, and ensure that your set looks naturally beautiful for years to come.