Why Does teak wood turn gray?
First, it is important to understand that what protects teak wood is the unique combination of the density and the natural oils and resins in the wood. The teak wood is honey brown all the way through, not just on the surface. (see https://www.atlantateak.com/our-teak/). UV light and wind will dry the surface and cause the top to turn gray. The gray color is not an indicator of lower quality. It is just cosmetic.