Calcário vs. incrustação
While both terms relate to hard water deposits, the distinction lies in the form and severity: calcário refers to the mineral substance itself, whereas incrustação refers to the hard physical layer or buildup that adheres to a surface.
Calcário
B1This word refers to the mineral (calcium carbonate) found in hard water. It is used to describe the substance dissolved in the water, the general concept of limescale, or the white powdery stains found on sinks and taps.
A água da torneira tem muito calcário nesta cidade.
(The tap water has a lot of limescale in this city.)
Preciso de comprar um produto para remover o calcário do duche.
(I need to buy a product to remove the limescale from the shower.)
O filtro ajuda a reduzir o calcário na água de beber.
(The filter helps reduce the limescale in the drinking water.)
Estas manchas brancas são apenas calcário.
(These white spots are just limescale.)
Incrustação
C1This refers to the act of crusting over or the resulting hard layer of scale. It implies a solid, stubborn accumulation stuck to pipes, heating elements, or machinery that is difficult to remove and causes damage.
A resistência da máquina de lavar avariou devido à incrustação.
(The washing machine's heating element broke down due to scale buildup.)
Os canos antigos estão bloqueados por uma incrustação espessa.
(The old pipes are blocked by a thick layer of encrustation.)
A limpeza regular previne a incrustação no interior do aparelho.
(Regular cleaning prevents hard scale buildup inside the appliance.)
Tivemos de raspar a incrustação do fundo da chaleira.
(We had to scrape the hard scale off the bottom of the kettle.)
Summary
Use calcário when talking about the minerals in the water or surface stains, but use incrustação when describing a hard, damaging crust or thick accumulation inside pipes and machines.