karkaistuja

Karkaistuja is a Finnish adjective form used to describe materials that have undergone karkaistus, or tempering. The term is most commonly seen in phrases such as karkaistuja laseja (tempered glass) or karkaistuja terästuotteita (tempered steel products). As a plural modifier, it indicates that multiple items of tempered material are being referred to.

Karkaistus for glass, or thermal tempering, involves heating glass to a high temperature and then rapidly cooling it. This creates a layer of compressive stress on the surface, which increases strength and resistance to thermal stress. Tempered glass is typically about two to five times stronger than ordinary glass and is used in applications where safety and durability are important, such as automotive windows, shower enclosures, and some smartphone or display screens. If tempered glass breaks, it shatters into small, blunt pieces rather than sharp shards, reducing injury risk.

Karkaistus for steel involves heat treatment, including hardening (quenching) and subsequent tempering to achieve a balance of hardness and toughness. Tempered steel is harder and more wear-resistant than untreated steel, yet retains more toughness than through-hardened forms. It is commonly used in blades, tools, springs, gears, and structural components where strength and resilience are required.

In Finnish technical usage, karkaistuja serves as the plural form in noun phrases describing tempered items, while the base forms karkaistu (tempered) or karkaistus (tempering) refer to the material state or the process itself.