If you want to seal natural wood without darkening it, there are a few things you can do. One option is to use a clear sealer like polyurethane. This will protect the wood from moisture and dirt while still allowing the grain to show through. Another option is to stain the wood with a light colored stain before sealing it. This will give the wood some color without making it too dark. You can also try painting the wood with a white or light colored paint before sealing it. This will make the wood appear lighter in color while still protecting it from moisture and dirt.