What is encapsulation primarily used for?

Encapsulation is primarily used for sealing hazardous materials, particularly in situations involving asbestos or lead-containing materials. This method involves enclosing the hazardous substances in a protective barrier or sealant to prevent the release of harmful particles into the air. It effectively contains the dangers to ensure safety without the need for extensive removal processes, which can be risky and costly.

The other options, while they may have their own relevance in various contexts, do not specifically target the primary application of encapsulation. Isolation of structures may be involved in a variety of construction or engineering contexts but does not focus on hazardous materials specifically. Similarly, while removing harmful substances is crucial in environmental health and safety, it does not reflect encapsulation's primary purpose, which is about containment rather than elimination. Lastly, applying decorative finishes pertains more to aesthetics in design and construction rather than addressing hazardous material safety concerns. Therefore, sealing hazardous materials is the correct context for encapsulation.