EVERYDAY MATERIALSAtlas
Material behaviour

Barrier performance

Keep contents and surroundings apart.

What it means

A barrier limits the passage of gases, liquids, vapour or light. These are separate demands. Small molecules can permeate some polymers, and a seam or pinhole can dominate the performance of a package. Combining layers allows each material to address a different route through the wall.

Look for it in everyday life.

Some cartons combine a fibre structure, polymer seals and an aluminium barrier.

Meet it in a material.

Zinc

A layer that protects another metal.

Metals

Soda-lime glass

The familiar glass of bottles and windows.

Glass & ceramics

Porcelain

Soft clay becomes a hard, dense vessel.

Glass & ceramics

PET

A clear bottle and a fleece share a polymer.

Polymers

HDPE

A tougher bottle from more orderly chains.

Polymers

LDPE

Branching makes a familiar flexible film.

Polymers

EPDM rubber

A flexible seal for weather and water.

Polymers

Follow the evidence

Original explanations informed by the sources below. Technical and industry sources support material behaviour; industry environmental marketing is not treated as a universal comparison. Read our editorial method.