EVERYDAY MATERIALSAtlas
Material behaviour

Density & weight

How much mass fits in a space?

What it means

Density is mass per unit volume. A lower-density material can make an equally sized solid part lighter, but equal size is not always a fair comparison. A designer may need a thicker wall, a different joint or more reinforcement to do the same job. Compare whole components that meet the same requirement.

Look for it in everyday life.

Aluminium bicycle tubes are often larger in diameter than slender steel tubes.

Meet it in a material.

Aluminium

Light enough to carry. Adaptable enough to shape.

Metals

Titanium

Strength and corrosion resistance without steel’s density.

Metals

Polypropylene

A moulded hinge that bends again and again.

Polymers

Wood

Structure grown in directions, not poured into a mould.

Natural materials

Cork

A springy material harvested from bark.

Natural materials

Carbon-fibre composite

Strength follows the direction of the fibres.

Composites

Acrylic (PMMA)

Clear plastic that can become a shaped window.

Polymers

Concrete

Stone grains held by a reacting binder.

Composites

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.