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.
Discard sunscreen that is past its expiration date. If you buy sunscreen that doesn't have an expiration date, write the date of purchase on the bottle and be sure to throw it out within three years. Also, discard sunscreen that has any obvious changes in color or consistency.