For what purpose are straight tweezers primarily used in eyelash extensions?

Straight tweezers are primarily used in eyelash extensions to isolate natural lashes, which is a critical step in the application process. Proper isolation ensures that each natural lash is separated from its neighbors so that the extensions can be applied individually without sticking to multiple lashes. This technique is vital for achieving a clean, natural look and preventing damage to the natural lashes.

While the other options represent tasks that may be performed during the eyelash extension process, they are not the primary purpose of straight tweezers. For instance, cutting false lashes typically requires scissors designed for precision, removing excess glue may involve other tools better suited for that purpose, and combing through lashes is often done with special lash combs or brushes. Thus, the specific design and function of straight tweezers make them ideal for the isolating technique crucial to the success of eyelash extension applications.