Why must end grain surfaces be sealed thoroughly?

Thoroughly sealing end grain surfaces is crucial primarily to prevent moisture entry. Wood is a natural material that can absorb moisture from the environment, and the end grain is particularly porous because it consists of the raw cut surface of the wood. When wood absorbs moisture, it can lead to swelling, warping, or even rot, which greatly affects the structural integrity and overall performance of the wooden components used in aviation.

Sealing the end grain helps create a barrier that keeps moisture out, minimizing these risks and ensuring that the wood remains stable over time. This is especially important in aviation, where weight, strength, and durability are critical factors. Proper moisture management through sealing not only preserves the material's properties but also extends its service life, making it essential for maintaining safety and performance in aviation applications.