Right after we install any granite I can almost guarantee that very soon the question will be asked, "How often do we need to seal this?", which is always followed by, "How many coats of sealer should we use?"

 

Looking at the coating question first. If you are going to need to seal the stone, you aren't actually going to be coating it. Coating refers to something that is applied and sets up like a film or a protective coating, which really is not the case. The very nature of why a stone would require protection means that the stone is absorbent, so what you are going to be doing is applying a liquid that will be impregnating or absorbed into the stone. So it is really applications, not coatings.

 

Backing up to address the first question. "How often do I need to apply a sealer?" No two slabs of granite are alike. Part of the desirability of granite is because it is natural and it has individuality. Thinking along these lines then it is only natural to consider that no two pieces of granite will have the same absorbent qualities. Granite comes from all over the world and therefore that beautiful green granite from China will have different characteristics then the beautiful green granite from Africa.

 

So what are you to do, and why is there so much confusion? Well, first off if anyone is to blame it probably would be the stone industry itself. There is no doubt that some stone needs a sealer, but just as true there is some stone that doesn't. People get a bit insecure about this expensive stone they have just purchased and are scared of what could happen to it. You just paid all that money for it and now you certainly don't want to ruin it. Unfortunately, the stone industry instead of looking at each problem individually rather has just taken a blanket approach to it, to seal everything and seal often. I guess if you are a retailer of granite sealers you can't complain since you're selling product to everybody whether they need it or not.

 

But the reality is less than 20% of granite actually requires being sealed. That means that upwards of 80% of the granite installed in homes requires no sealer at all. 

 

So how do you know if you have a stone that falls into the 20% category or not? A simple test that is based on nature. Have you ever seen a granite stone in nature or a granite statue after a rain? Watch it carefully and see what it does. You probably will see it dry very quickly, almost instantly. What you are seeing is a granite that doesn't absorb water. This is the same principal used to test your granite. Simply putting a small amount of water on granite and letting it sit for about 15 minutes is all that is required. At the end of 15 minutes wipe the water off with a paper towel. Now examine the stone. Did is it darkened where the water was? If so your stone requires a sealer and falls into the 20% If not then you don't. In fact if you tried to seal the granite that didn't darken, the sealer would just get wiped off since the stone simply won't absorb it.

 

Now go on to test number two. Drop a drop of mineral oil on the slab and leave it for 10 minutes. Clean it off and see what you get. (Don't worry, any dark spot will lighten and disappear within 20-30 minutes and not hurt the stone) If you have a darkened spot then your stone is susceptible to a staining agent. You need to seal the stone. I recommend a solvent based sealer/impregnator. There are water based products on the market but solvent based is still the king, at least for now.

 

So the final thing to know is how often to re-apply your sealer. It's actually pretty simple, when you start to notice your stone starts to darken again and isn't repelling water like it used to, it's time for another application. How long might this be? It could be 1 year, 5 years or 15 years. As you now know all stone is different and will absorb and repel differently, but you now know that every 6 months or once a year is only a guess. Now you have the information to test and re-apply your sealer only when it is required.