What Is Granite?

• Granite is a natural stone formed of many different minerals, including quartz, biotite and various feldspar. Sometimes it even includes familiar gems such as garnet and apatite. Granite is classified as igneous rock, the oldest known type of rock. The root of the word igneous comes from the Greek word for fire, indicating that the layers of the granite were melted together millions of years ago, often within volcanic magma. Veins of granite are usually comparatively small, which means that granite remains fairly expensive and appears high-end when used in homes. The price and supply of granite is also affected by the very involved process used to remove the granite from its original location.
  
  

Why Drill Granite?

• Since granite is purchased in preformed slabs that are finished by the supplier to your specifications, you may wonder why it would ever be necessary to drill granite. One of the most common reasons is to add a fixture, such as a sink. Even if you purchased a home that already had granite countertops with preinstalled sink hardware, many people decide at some point to change from a single-handle configuration to a double-handled faucet. This necessitates drilling additional holes to accommodate the new fixture. A second purpose for holes drilled in granite is to install appliances such as under-mount dishwashers beneath a granite countertop. These appliances are generally secured with screws, but it is quite impossible to sink a screw directly into granite without cracking the countertop. Therefore, drilled pilot holes are required for adding the screws.
  
  

The Correct Drill Bits for Granite

• The correct drill bit for granite will depend primarily on the size of the hole you wish to make. Most importantly, you will need special bits for your drill to make holes in granite. Sometimes, you will need a special saw, and will forgo a drill altogether. For drilling small holes with a drill, a diamond-core bit or masonry bit is the correct choice. These bits are stronger than the standard steel drill bits, cutting through the granite with a fair amount of ease. In addition, these bits lack the sharp edges of standard drill bits that are meant to "bite" into wood and other softer materials but which simply slide around on granite. It is important not to use regular drill bits on granite, as the movement may cause accidents, and the resistance will eventually burn up your drill. Larger holes should be made with a diamond hole saw. These saws also use diamond-core bits, but can accommodate larger ones than can many drills. A diamond hole saw is the correct tool for making holes to accommodate fixtures such as faucets and handles.
  
  

Drilling Process

• When drilling small holes, you will want to keep your bit moist for ease and to minimize mess. A small plastic capful of oil will do the trick. The type of cap found on smaller laundry detergent bottles or one meant for measuring cough syrup is the perfect size. Fill the cap full of vegetable oil and place it directly over the area where you intend to drill. By drilling through the oil and the bottom of the cap and into the granite, you are ensuring that the bit stays moist with every turn. Making larger holes does not require a wet process, but does demand more preparation and care. You should always wear a paper dust mask or respirator over your nose and mouth to avoid breathing in granite particles. Apply the drill or saw evenly to the surface of the granite in a slow, controlled motion. Steady pressure is necessary to create a perfect hole, so be sure you have adequate arm strength.