Most sinks advertised as "granite" are actually made from granite composite, a less expensive, easier to work with material made of real granite suspended in a resin base. According to Astracast, a manufacturer of granite composite, these sinks can be up to 80 per cent natural stone. They provide the durability and look of granite with improved shock resistance and a wider range of shapes. Like natural granite, granite composite sinks require some special care and maintenance.
Your granite sink may include smooth, counterlike surfaces that are tempting to use as a cutting board. Routine contact with knife blades, however, can leave scratches and scores in your sink. It can also slowly dull your knives. Always place a plastic or wooden cutting board over the sink top before chopping. Avoid sharp, sudden impacts, such as dropping a metal pan or dish into the sink. It can scratch or chip the surface. Granite composite sinks are also heat-sensitive. Never place a hot pan or dish into the sink. Temperatures over 260 degrees Celsius can melt or discolour the resin binder.
Clean your granite composite sink on a regular basis, using plenty of water and a non-abrasive or mildly abrasive cleaner such as baking soda. Never use a heavy-duty scouring pad, steel wool or abrasive cleaner on granite composite. These materials can create many fine scratches that encourage stains and discolouration. Avoid ammonia or strongly acidic cleansers, as these can etch the sink surface. After cleaning, rinse the sink well and wipe it dry using a soft, clean cloth. This discourages water spots and built-up soap scum.
In areas with hard water, your sink may develop a build-up of mineral deposits, such as lime scale. These deposits can dull or discolour your sink. They may also absorb colour from beverages such as coffee, grape juice or wine, creating the appearance of a stain. Remove these mineral deposits using a mild acid, such as diluted lemon juice or vinegar. Rinse thoroughly after using acids to clean your sink. This reduces the risk of etching.
Even the best cared-for granite composite sink may develop stains over time. Biologically activated washing powder or a speciality composite sink cleaner can remove these stains. For stubborn patches, CM StoneWorks recommends a soft scouring pad. Rub the stained area gently with this pad, using many different motion patterns to decrease the risk of scratching. For very stubborn stains, soak the area in a 50 per cent chlorine bleach solution.