Granite is a popular, beautiful and profitable countertop material for many of today’s fabricators, and it is common knowledge there are many different types of granite available on the market. However, to my knowledge, there is no universal testing standard as to what types of granite work best for a given application. And even if there were, different granite suppliers have different names for the same or similar types of granite which adds to the confusion. When it comes to determining which types of granite are most suitable for a kitchen application, or which types should be sealed with a high-quality sealer, there are a couple of tests fabricators may want to perform on a sample of a given type of granite.
The lemon test is to determine the ability of a type of granite to resist etching. Follow the steps below:
1. Place a wedge of lemon or lime, cut side down, on a sample of the granite and leave it overnight.
2. In the morning, remove the lemon slice and wipe the sample down. Then hold it at an angle to the light.
3. Check for a rough spot where the lemon was placed.
4. If the material is subject to etching, the spot the lemon was in will appear dull and rough.
Etching normally occurs where calcium or calcite is present in the make-up of the stone. If a sample reacts to the lemon wedge, we do not recommend this for a kitchen application, or at least a high-use kitchen application.
WATER ABSORPTION TEST
You may also want to test the suitability of your granite to resist water absorption. Basically, the tighter the grain of the granite, the less absorption there will be.
To conduct a water absorption test, follow these steps:
1. Place a few small drops of water on the sample granite.
2. Let the water stand for about 15 min.
3. Wipe off the excess water.
After wiping the excess water, you may notice a dark spot. This means the granite has absorbed the water and is subject to staining. In these cases, a sealer is recommended.
If you wipe the excess water and there is no noticeable difference, then the granite has a tight grain structure and will be more resistant to staining.
If the granite sample absorbed the water IMMEDIATELY, it is very porous and extra care is needed. We recommend a high-quality sealer in these cases to help prevent staining.
Because there are different types of sealers with different procedures for use, you should use the specific sealing procedures recommended by the supplier or manufacturer of the sealant you choose.
About the author: Andy Graves is the owner of Olive Mill, a fabrication company that supplies various types of countertops including quartz, natural stone, concrete and solid surface, and runs www.TheFabricatorNetwork.com, an online association of countertop fabricators. He has been a fabricator since 1986 and can be reached at email@example.com.