Worth a look? http://www.liutaiomottola.com/PrevPubs/WipingVarnish/WipingVarnish.htm
So what varnishes have you wiped on before?

Varnish may be used- like lacquer - as a generic term for any clear finish, but strictly speaking, a varnish is any resinous solution that cures or dries to a protective finish. Modern usage is that the solvent matters - varnishes that have an oil solvent are referred to as oil varnishes, and varnishes which use alcohol -as did many of the older instrument varnishes - are spirit varnishes. Shellac - along with a long list of other resins -- anime, benzoin, copal, damar, gum arabic, gum mastic, and sandarac to name seven common resins -- may be used singly or in combination for spirit varnishes.

Oil varnishes have their resins dissolved in oils, and date from the Middle Ages when craftsmen discovered that amber could be heated in linseed oil to produce a naturally polymerizing finish which was much more solvent and weather-resistant than other available finishes. Today, oil varnishes are the finishes which most craftsman think of when 'varnish' is mentioned, and the resins used include both natural as well as synthetic resins such as phenolic and urethane. Shellac - an insect-derived resin common in spirit varnish formulations - is not easily dissolved in most oils, so is not generally used as a resin component in oil varnishes.

Oil varnishes are further classed as long oil, medium oil, and short oil, with long oil varnishes (50 to 100 gallons of oil to every 100 pounds of dry resin) referred to as spar varnishes for their greater flexibility and ability to absorb impacts, and and some short oil varnishes (5 to 12 gallons of oil per 100 pounds of resin) referred to as table-top or rubbing varnishes due to their ability to resist scratching and to be rubbed out in a reasonable period of time to a desired level of gloss. In between are the medium-oil varnishes, with 12 to 40 gallons of oil per 100 pounds of resin, which possess some of the attributes of both spar and rubbing varnishes (reasonable flexibility with decent scratch resistance).

Wiping varnishes like TruOil and Watco use long or medium oil varnishes as a base, but add quite a bit of solvent, so while they may be padded on (versus brush or spray), it takes many, many coats to build to a finish which can be level sanded and buffed to a high gloss. Most conventional varnishes can be thinned for pad or rubbed application.

In general, oil varnishes provide a very high degree of protection once fully cured, may be brushed, sprayed, or wiped on, may be built up enough to allow the finish to be level sanded and rubbed or buffed out to a desired level of gloss, and are more sweat, solvent, and impact resistant that conventional instrument lacquers, but less so than the latest generation of finish technology such as two pack urethanes or polyester finishes. Unfortunately, classic phenolic/tung short oil formulations - easy to apply, relatively quick to cure, and easy to level sand and buff - are rapidly disappearing from the marketplace as finishes with lower or zero VOC content become available.