QUARTZ NANOGUARD Countertop Protector is your secret defender from life’s little mishaps. Whether it’s a brand-new countertop, or one installed years ago. QUARTZ NANOGUARD Protector helps repel liquids and block stains without changing the look and feel of Quartz, Quartzite or Engineered Stone like Composite Marble.. This means you can wipe the surface clean before the mess sinks in for beautiful, long-lasting stain-free appearance for years to come.