It is sometimes convenient to categorize packages by layer or function: primary, secondary, etc. 1  Primary packaging is the material that first envelops the product and holds it. This usually is the smallest unit of distribution or use and is the package which is in direct contact with the contents.
Sunscreen does not stop working the day after the expiration date. Sunscreen is usually effective for at least three years, which is usually longer than the expiration date marked. What to Look for When You have Allergies or Sensitive Skin. Skin allergies can be a common problem. For individuals with sensitive skin, try physical sunscreens. Physical sunscreen protects your skin by deflecting or blocking the sun's rays, while chemical sunscreens absorb the sun's rays.
He also recommends that every year, throw out last years sunscreen and use new. It's safe to use sunscreen and such after the expiration date (unless it smells funny or such (this also applies before the expiration date)), it's just that it might not be as effective in protecting you against the sun.