Acronym and details:  PE, low-, medium- and high-density: LDPE, MDPE, and HDPE

Group:   thermoplastic

Developed:   1933 low density but used for military purposes until 1945; 1953 high density

Trade names:   Polythene; Alkathene; Tyvek

Manufacturing process:   blow moulding; extrusion; injection moulding; rotational moulding

Cost:   very low

Colour:   any

Transparency:   naturally translucent but can be opaque

Rigidity:   semi-rigid to flexible depending on density

Feel:   varies depending on density

Smell:   wax

Other:   scratches with fingernail; currently LDPE is the plastic with the highest volume of use

Typical uses:   replaced enamelled kitchenware: bowls and other domestic wares, first squeezable bottles (e.g. for washing up liquid) and airtight food containers; road cones; ‘poppit’ beads; packaging film, e.g. carrier bags

Degradation:   yellows, stiffens, and embrittles