Epifanes is considered by many to be the best varnish around. This is a spar varnish, with UV inhibitors built in. It is made with a combination of phenol and alkyd resins for superior protection. They also use tung oil, rather than the less expensive linseed oil. The best of everything is used in this varnish, to provide the best possible end result. Epifanes also has a number of other varnish products, including one that provides a hand-rubbed appearance.
McCloskey is actually an owned brand of Valspar, who bought them out many years ago. This is another spar varnish, designed for use outdoors. As such, it has the necessary UV protection and flexibility needed to survive the harshness of the outdoor environment. This varnish is made from tung oil, although the manufacturer’s information doesn’t say what type of resin they are using. The only thing we’re sure of is that it isn’t a polyurethane. It adheres extremely well to oily woods, such as mahogany. Available in both satin and gloss finishes.
Rockhard is a varnish specifically formulated for use on tabletops and other surfaces which are likely to receive lots of rubbing. It is very hard, being made of urethane resin, so it resists scratching well. It also resists the damaging effects of water, alcohol, foods, chemicals and detergents. This is an indoor varnish that is not UV protected for outdoor use. Being a hard varnish, it’s not flexible enough for use where changes in humidity would affect it. The low VOC formulation is great for working indoors. Available in both gloss and satin finishes.
Cabot makes another spar varnish, at a lower price than the Epifanes varnish listed above. This one uses alkyd resin. The manufacturer doesn’t mention what type of oil is used in their literature, but based upon the price, I’d say it’s probably linseed oil. Nevertheless, this varnish provides an excellent finish for both indoor and outdoor uses. It is UV protected, and being a spar varnish it is designed to be flexible and handle the effects of weather. It is also available in gloss and semi-gloss.
We couldn't put this list together without mentioning Minwax, the biggest name in varnish and stains. While they don’t produce a spar varnish, they do produce excellent polyurethane varnishes at a reasonable cost. This is an indoor varnish, designed to provide superior scratch resistance. However, it doesn't work as an exterior varnish, as it is not designed for that. Minwax calls this a “fast drying” varnish, saying that it can be recoated in four to six hours. However, many other varnishes can be recoated in the same time, so take that name with a grain of salt.