QUESTIONQuality of Granite - We just purchased a new home, but not directly from the builder. We closed on the same day as the original sale from the builder, though. Our problem is that the kitchen granite is very visibly porous and has millions of mini cracks on the surface. It is not smooth and no matter how much we clean it always looks dirty. The builder sent the granite installer to "re-seal" it, but whatever they did made no difference. We have had granite before and this had never been an issue. The granite contractor says it is the nature of this granite and there is nothing they can do about it. To me, it is unsanitary as food gets stuck on the "unfinished" portions and it is very hard to clean. Could it be that this is substandard granite? Could the quality of the granite be tested? If so, how much would it costs?
ANSWERANSWER - There is a lot of natural stone sold as granite that is not true granite. Due to the large demand for stone today, stone that would not have been sold or used before is now.
You might have what is called an over-burden stone, which is quarried at the top of the mountain and it tends to be more unstable and have more voids in it.
Some of these stones that are over-burden or not true granites are very unique looking and can be very beautiful. So some people may choose to select this material knowing that it may not meet the minimum standards for that category of stone.
Every category of stone has various levels of performance depending on what type of stone it may be, which quarry it was mined from, and which part of the quarry it was mined from. Stone is a natural product and will vary in looks and performance.
Generally the same stone from the same part of quarry will vary, but relatively consistently.
There are ASTM standards for each category of stone in terms of what the minimum physical properties should be. The Marble Institute of America publishes what those minimums should be if the stone is tested per the respective ASTM standard. This series of the 5 basic tests cost approximately $1,500.
Many of the slab stone imported today is impregnated with a resin to make them more durable. There is a chance what you are seeing are cracks in the resin coating. If it is porous then it isn’t likely true granite, and it may be over-burden granite if you have voids and pits. Good Luck!