"Surface impurities" refers to dirt, dust, or other unwanted substances that are found on the outer layer or visible part of an object or surface. Full definition
The Grapefruit Glycolic Wash gently removes surface impurities with its high concentration of Vitamin C. (kneadtocook.com)
The hooks are made of lightweight aluminum for easy crocheting and each one of the hooks undergoes a special anodizing process that eliminates surface impurities. (geekwrapped.com)
A balancing foaming cleanser for normal to combination skin that lifts away surface impurities leaving the complexion fresh and clean. (jurlique.com)