When applying tape for mirrors, which method should NOT be used for sealing against condensation?

When installing mirrors and applying tape to seal them, trimming the tape square is not an effective method for sealing against condensation. A square cut edge can create a gap or edge where moisture may penetrate, which can ultimately lead to condensation build-up behind the mirror.

In contrast, using double-backed tape provides a strong adhesion that allows for good sealing against moisture, and sealing with silicone creates a flexible, watertight barrier that is effective in preventing water from getting behind the mirror. Trimming the tape to a point can also enhance the application by providing more overlap and reducing the chance of moisture seeping in. Therefore, avoiding a square cut provides better protection and ensures a more reliable adhesion to inhibit condensation.