Why is it better to apply finishes before assembly?

Applying finishes before assembly is advantageous because it ensures that all surfaces of the cabinetry, millwork, or trim are equally sealed. When pieces are finished separately before assembly, it's easier to cover all surfaces, including edges and hidden areas, that might be challenging to reach after the components are put together. This prevents moisture penetration and helps to protect the material more effectively from potential damage.

When the assembly happens first, there can be gaps or overlaps that are difficult to finish adequately, leading to uneven sealing. Additionally, this method allows for simpler application of the finish, as the pieces can be laid flat and maneuvered easily in a well-ventilated area. By sealing all surfaces uniformly, you also enhance the longevity of the project, as wood and other materials are better protected against wear, tear, and environmental elements.

The other options, while they may seem attractive — such as faster completion or consistent coverage — don't address the fundamental benefit tied to sealing all surfaces uniformly, which is critical in achieving a durable and visually appealing final product.