Unveiling the Mystery of Granite Discoloration
Have you experienced your granite under appliances retaining its original color compared to the surrounding areas that have darkened over time? Here’s why and some tips to prevent and manage this issue.

Granite countertops are prized for their beauty and durability, often serving as a central piece in kitchens worldwide. However, homeowners sometimes discover a curious phenomenon: granite under appliances like toaster ovens or beneath placemats retains its original color, appearing lighter compared to the surrounding areas that have darkened over time. This article explores the causes behind this discoloration and offers tips on how to manage and prevent it.

Understanding Granite Discoloration

Granite is a natural stone composed of various minerals, including quartz, feldspar, and mica, which contribute to its color and pattern. While granite is known for its toughness, it is not wholly impervious to the effects of exposure to light, chemicals, and heat.

  • Sunlight Exposure: Constant exposure to sunlight can cause the granite’s color to fade or darken, depending on the types of minerals in the granite. If the granite has been reinforced with resins, the resins may be affected by UV rays. Areas covered by appliances or mats are shielded from these effects, hence they retain their original appearance.
  • Heat and Moisture: Heat from appliances like toaster ovens can influence the coloration around these areas. Moisture, whether from cooking, cleaning, or ambient humidity, can also seep into the stone if not properly sealed, leading to darkening due to mildew or other moisture-related reactions.
  • Chemical Exposure:  In general, granite is very resilient and will not etch from common cleaning agents or spills from acidic substances like vinegar or lemon juice, but some granites have binders that may react with certain chemicals and alter their color. Areas under appliances or mats are often protected from such exposure, preventing these chemical reactions.

Prevention and Remediation

To manage and prevent discoloration of granite countertops, consider the following tips:

  • Regular Sealing: Apply a sealant to granite countertops at least once a year to protect against moisture and chemical penetration. This barrier can help maintain the uniformity of the stone’s color.
  • Consistent Cleaning Practices: Use gentle cleaners specifically designed for natural stone. Avoid harsh chemicals and scrubbing pads that might scratch or etch the surface.
  • Sunlight Management: If possible, use blinds or curtains to minimize direct sunlight exposure on the granite surfaces, especially in areas prone to long-term sunlight exposure.
  • Rotate Accessories: Periodically move appliances, mats, and other items sitting on granite surfaces to allow uniform exposure to light and air.

By Fred Hueston. This article is one of a series of articles written and published on behalf of Surface Care PRO Partners.