You may have just purchased a stone counter or installed stone tile in your home and you are wondering a loud why the water you just spilled has darkened the stone. Answer, all stone is porous to some degree. That’s correct, all stone. Marble, limestone, granite, it doesn’t matter. All natural stone needs to be sealed.

I was recently reminded of the need to seal stone at a dinner party by a friend’s neighbour. My wife and I were visiting friends and while we were sharing pre-dinner drinks someone mentioned that I had a backround in stone. Suddenly one of the guests piped up and complained that water was leaving dark spots on her newly installed granite counter top. She was upset because she had been led to believe that granite counter tops are “maintenance free”. Wasn’t granite one of our earth’s most dense and imprevious stones? Did she purchase a faulty product? Worst yet, had she been misled? Yes, no and maybe a little.

It is most certainly true that certain stones are denser than others with granites leading the pack. It is also true that the denser the stone the easier it should be to maintain. However, all stones have pores and granites are no exception. There is also a large variance of the level of absorption bewteen the different granites that are available for counters and flooring so it can get a little complicated.

Not to worry. Fortunately for most of us, including the neighbour mentioned above, water is your classic canary in the coal mine. Water is a relatively small molecule and as a result it can be easily absorbed into stone darknening the colour of the stone. This is a sign for you that your stone needs to be sealed. The nice thing about plain water is the fact that it will also evaporate and leave no permenant stain.

Here’s the fix. You can address the problem of absorption in stone with a sealer. Acutally the name sealer is a misnommer. You want an impregnator which is a “sealer” that will be absorbed into the stone and not simply sit on the stone like a wax.

There are many impregnators on the market, water-based, solvent based, silicone, co-polymer, ect. Do some homework. I prefer a solvent based copolymer. I’m sure that the water based products will soon be as easy to apply and work as well as the solvent based ones but for now I’ll take the solvent based. In any case do some research and pick a product that will work well with your stone.

First read the instructions. Second test the product on a small inconspicuous spot on the stone. Most impregnators are as easy to apply as lemon oil on fine furniture. You typically apply a thin coat of the sealer to your clean dry stone with a clean dry cloth or you might apply it by low pressure spray. Then after a minute or so but before the sealer dries you then pick-up any excess impregnator with another cloth and buff the stone dry.

Apply at least two (2) coats of sealer. Again I can’t stress is enough, read the product instructions carefully. Some impregnators work best with wet on wet applications of sucessive coats. Others require a drying time inbetween the applications. In either case when you’ve finished applying the sealer wait over-night before you use the stone. Then test the stone with water. If the stone darkens you need another application of the impregnator.

Good luck and don’t forget about your old friend water, the canary in the coal mine when you talk about stone.

See you at my next post.