What function do varnishes or sealants serve in wood aviation applications?

In aviation applications, varnishes or sealants play a crucial role in providing a protective barrier against environmental factors. Wood used in aircraft can be susceptible to moisture, ultraviolet light, temperature variations, and fungal or insect infestations. The application of varnishes or sealants helps to mitigate these risks by creating a surface layer that repels water and prevents absorption, which can lead to swelling, warping, or degradation of the wood. It also protects against UV light that could degrade and discolor the wood over time.

While enhancing the aesthetic appeal of wood is an added benefit, the primary function of these coatings is protection. The coatings do not inherently increase the weight of wooden components significantly, and while they may aid in adhesion to a certain extent, their primary purpose is not bonding joints. Thus, the main function of using varnishes and sealants in wood aviation applications is indeed to provide a robust protective barrier.