Structure

• Enamel sinks have a cast-iron core, which is dipped into hot porcelain enamel and then baked in a kiln at extremely high temperatures. The result is a tough, smooth surface that resists heat damage and is easy to clean. Newer enamel sinks may have a steel core instead of cast iron. These sinks tend to resist rust better, and are lighter and less expensive than iron, but look much the same when finished.
  
  

Abrasion

• While enamel is an extremely durable material, abrasive cleaners or cleaning tools can scratch its surface. To protect your enameled sink, always clean with a soft cloth or sponge, never with steel wool or a similar scratchy material. To remove caked-on food, try soaking the area, and then rubbing it with a soft tool. Abrasive cleaners can help remove the worst dirt, but they tend to scratch the surface, encouraging future staining. Avoid them whenever possible.
  
  

Impact

• Cast-iron enamel sinks are also susceptible to impact damage. Dropping a heavy utensil or pan into your sink could chip it, create cracks or even knock out chunks of the enamel. Use a rubber drain mat at the bottom of your sink, and take care when washing heavy dishes. According to Consumer Reports, some enameled cast-iron sinks will also chip when sharp objects, such as a knife, are dropped into them. Chipped or cracked enamel stains more easily, and may allow water to penetrate the sink coating, eventually rusting the sink.
  
  

Repair

• The only way to completely fix scratched or chipped sink enamel is to remove the original coating and bake on a new coat of enamel. This process is costly and inconvenient, so most homeowners go with less complete, but less expensive, fixes. Buffing the sink can remove minor scratches by taking off a minute layer of enamel. When done correctly, buffing results in a smooth sink that stains only a little more easily than it originally did. Chipped surfaces can often be filled with small amounts of acrylic repair material. More serious problems may require a full resurfacing, using epoxy. This material isn't quite as durable as the original enamel, but it blends in well and can restore your sink's original appearance.