Watco Danish Oil and tung oil are two types of wood-finishing oils with distinctly different properties. Watco Danish Oil is a brand name of Danish oil. Both Danish oil and tung oil can achieve the result of a finish on your woodwork, but maintenance and durability as well as the amount of time invested in finishing the item vary between the two products.
Danish Oil Properties
Danish oil is an oil-varnish blend. According to the Popular Woodworking website, amateur woodworkers made boiled linseed oil easier to apply by thinning it with turpentine or white spirit, "so the proportions were about one-third linseed oil, one-third varnish and one-third thinner." This new solution also dried quickly. Manufacturers capitalised on this homemade solution by making types of Danish oil readily available in hardware stores.
Tung Oil Properties
Tung oil is derived from the nut of the tung tree, which is found primarily in China. In raw form, tung oil is an effective coating for woodwork that requires a hardened, protective seal. Tung oil can be applied in several coats to achieve a hardened seal on wood.
Application and Durability
A Danish oil application will remain durable for many years due to its blend of oil and varnish. According to Popular Woodworking, varnish is created by cooking an oil with a resin to make a blend that is durable and hardens upon drying. This makes it possible to apply Danish oil in less time and in fewer coats than tung oil.
Tung oil is to be considered a maintenance application and should be applied at least once a month to maintain a level of protection and sheen on woodwork. Applying several coats of tung oil is recommended, and it takes more time to apply tung oil because each coat should have 24 to 48 hours to soak into the wood and dry.
Food-grade Mineral Oil
Some mineral oil is considered "food grade" and can be applied safely to wood that comes in regular contact with food, such as butcher blocks and wooden utensils. According to the website Wood Finish Supply, "a cutting board surface is never 'Finished'--the oil is a continuing Treatment, not a finish." Because Danish oil is a mixture of chemical varnish and mineral oil, it should not be used on wood products that come in contact with food. Raw tung oil is safe to use in this instance.
Conscientious woodworkers use wood finishes that are appropriate for a wood item, including the amount of contact that will be made with the item over its lifetime. Tung oil may be a better choice for wood products that are often in contact with human hands. Danish oil may be a better choice for wood products that are used more for aesthetic than practical purposes.