Varnishes are widely used as a wood preservative and emphasize its natural beauty. Priming polyurethane varnish is mainly used to paint wood with a matte or glossy finish. You can also purchase paint that combines varnish with pigment, in different colors. There are many varieties of very resistant varnishes, like yacht varnish, used for painting decorative exterior structures. Cellulose varnish is equally durable, dries quickly and is available in pure and colorful form.
There are also a lot of preservatives, used for impregnating wooden structures standing outdoors.