What you need to know about
The biggest key to application of a finish of the tung oil flooring is preparation. The surface should be free of oil, dirt, grease and any other contaminates. Pure Tung Oil can not be applied over another type of finish. It can only be applied to a previous coat of Pure Tung Oil. For best results a previously finished floor should be chemically stripped of its finish, cleaned with TSP, then lightly sanded to open up the surface.
If the surface is not clean or has recently been stripped of its finish; it should be cleaned with TSP. TSP (Trisodium phospate) is a powdered heavy duty cleaner that will leave the surface free of contaminates. If you have a wood surface, which is old, and case hardened, it should be scuff sanded lightly with 150-grit sandpaper, to open up the wood to receive the oil. Sanding with too fine sandpaper will case harder the surface. If after removing finish you find black or brown stains, see Oxalic Acid wood bleach to remove them.
Finishing of Tung Oil Flooring
Following is the technique, which I found to work well, although there are many others who may have variations which work just as well.
The objective with Pure Tung Oil is to saturate the surface with as much oil as fast as possible and drive the oil into the cells of the wood getting maximum penetration but without leaving a film build on the surface. With very dense hardwood a thinner ratio than described below may be required. I can not stress enough if the oil and thinner mix is not soaking in the 40 minute application period, a thinner ratio should be used. For example: 1 part oil to 1 1/2 parts solvent. The oil to solvent ration can be variably adjusted any direction from a thicker mix to a thinner one. The difficulty is trying to find the ratio of oil to thinner with each coat so as to get the maximum oil to solvent ratio that will soak in. Also I must note, Minwax stains will not work with Pure Tung Oil. They contain varnish and will not let the oil penetrate.
Care and Maintenance of Tung Oil Flooring
To clean your tung oil flooring after the finish is cured a mild detergent such as "Ivory Dish Soap" or "Simple Green" will work. I am not fond of Murphy's oil soap as it seems to break down a finish over time. Stay away from harsh oil base cleaners and ammonia. You can use a "Scotch Bright" pad to clean tough spots every so often but try to avoid abrasion unless necessary. To clean black heel marks or paint splatter on your tung oil flooring, "Goof Off" or "Opps" work well. These products will not effect the cured finish. If you find you do scrub the finish too hard somewhere, just do a quick touch up with Pure Tung Oil thinned 1 to 1 with thinner on a nylon pad or stockings. Then let it dry for a day.
Here is a way to calculate how much Pure Tung Oil and Citrus Solvent you may need to finish the floor. This formula will assume you are cutting the oil one to one with solvent. Each gallon of oil will cover approximately 400 square feet undiluted. By diluting the oil one to one with solvent, it will cover 800 square feet. In our example we will assume you have 500 square feet to cover. This is the maximum amount of Pure Tung Oil you would need for your project and is based on using it on an Antique or old wood floor. Old wood will drink up much more oil than new wood. For new wood and hard woods (maple, birch, cherry) you should be able to reduce the amount of oil needed by 25 percent.
Day one 5 coats x 500 = 2500
Day two 3 coats x 500 = 1500
Day three 2 coats x 500 = 1000
5000 divide by 800 = 6.25
This means you would need 6.25 gallons of Pure Tung Oil and 6.25 Gallons of solvent.