Plastic bags are made out of “film,” or thin flexible sheets of plastic. Plastic film is typically defined as any plastic less than 10 mil thick. The majority of plastic films are made from polyethylene resin and are readily recyclable if the material is clean and dry.

The resin coding system was originally intended for rigid plastic containers only. However, many manufacturers put the code on plastic films too. If no resin code is printed on the plastic film or bag, the film’s application may indicate the resin type since different resins are chosen for their unique performance or observe the film’s characteristics and appearance and compare to the descriptions below.

Resin Code

Characteristics and Examples

LDPE – Low Density Polyethylene

Resin Code #4

  • Unpigmented films have high clarity, moderate stretch and strength characteristics.
  • Bags (e.g., thicker newspaper bags, bread bags)
  • Bubble wrap (may also contain nylon)

Note: Bubble wrap recycling can be difficult without local markets due to shipping constraints.

LLDPE – Linear Low Density Polyethylene

Resin Code #4

  • Unpigmented films have moderate clarity, slightly tacky feel to the touch.
  • Bags (e.g., clear, thin newspaper bags)
  • Dry cleaning film

MDPE – Medium Density Polyethylene

Resin Code #4

  • Unpigmented films have moderate clarity, poor stretch and strength characteristics.
  • Consumer paper packaging (e.g., toilet paper, paper towel)

Note: MDPE is a variation on the production of LDPE and is often labeled #4. It’s generally used as an alternative to other resins in film applications where strength is not required.

HDPE – High Density Polyethylene

Resin Code #2

  • Unpigmented films have some opacity, crinkle to the touch, low stretch, high strength, and can tear easily.
  • Most grocery bags
  • T-shirt bags
  • Bags with sealed air for packaging (e.g., air cushions)

Note: Release air from air cushions before including with bags.