Specialist technical principles

Bamboo is promoted as a sustainable alternative to traditional hardwoods because it regrows rapidly after cutting without replanting — bamboo is a grass, so the cut stems regenerate from the existing root system, and some species grow over 1 m per day.

Compression is a pushing force that shortens a material along its axis (tries to crush along its length).

Batch production makes identical items in fixed-size groups (batches), then the line switches to produce a different product. Examples: bakery batches, a furniture range built 50 at a time.

Cast iron is brittle under impact loading, which makes it unsuitable for a portable gym dumbbell handle (impact-loaded). The cast-iron dumbbell weight is fine because the loading is static; the handle takes shock loads on drop.

Air drying timber takes longer than kiln drying but uses far less energy — kilns burn fuel or electricity to heat the chamber, while air drying relies on ambient airflow.

Annealing softens a metal by heating it above its recrystallisation temperature and then allowing it to cool slowly, increasing ductility and reducing hardness.

In the ISO A-series paper-size system, each successive size has exactly half the area of the size below it (and twice the area of the size above): A4 is half the area of A3, A5 is half the area of A4.

Anodising thickens the protective oxide layer on aluminium, improving durability and corrosion resistance. It does not coat the part with gold, make it conductive, or remove its existing oxide.

ABS (acrylonitrile butadiene styrene) is used to make LEGO bricks because of its toughness and impact resistance; "Lego bricks have primarily been made from ABS since 1963."

Carbon footprint is the total greenhouse gas emissions associated with a product's full life cycle — including raw material extraction, manufacture, transport, use and disposal — not just the emissions at the factory.