"Paddles are tools, tools that should be used. Being made of wood it is inevitable that paddles wear, sometimes they get bumped and bruised while rock hopping, or scratched while learning sculling rolls. However the paddle gets worn or damaged, it is important to treat it well and take care of it like you would any other tool.
Small abrasions should be sanded down with ever smoother sandpaper, starting with maybe a 200 grade and ending with a 1000 grade. Minor nicks and bruises can either be sanded, or if they are more significant they can be smoothed out with a knife or spoke shave and then sanded. More significant damage may require epoxying or actually carpentry so in these instances I recommend consulting your paddle maker before commencing any work.
Once the surface is sanded smooth I recommend rubbing 100% pure Tung oil with a lint free cloth across the paddle surface, paying particular attention to the exposed end grain. The oil takes about 24 hours to dry. I like to do 2 or three coats of oil, twice a year. Once the final coat is dry I rub the paddle gently with bronze wire wool, this creates a silky gloss finish that is smooth to the touch.
If you take care of your paddle it will take care of you and should give you many years of service."
Be careful with the handling and disposal of the rags used to apply tung oil. The oil itself is not a problem, however the solvents used to thin the tung oil are highly flammable and combustible. Allow rags to thoroughly dry on a non-flammable surface (such as a concrete block), or washed, or soaked with water before placing in the garbage. Solvents can generate heat through an exothermic reaction with the air (oxidation), and this reaction accelerates as the rags get hotter, and this has been known to start unintended fires.
Tung oil, also known as China Wood Oil, Lumbang oil, Noix d'abrasin (fr.) or simply wood oil, is made from the seed kernels of the Tung tree (Aleurites fordii and Aleurites montana, family Euphorbiaceae). The A. fordii tree grows well in cooler climates, but can survive up to sub-tropical climates. A. montana is restricted to a more tropical climate. China, Argentina, Paraguay, Brazil and the USA are all major producers of tung oil.
Tung oil has been known about for hundreds of years in China, where it was used as a preservative for wood ships. The oil penetrates the wood, then hardens to form an impermeable hydrophobic layer (repels water) up to 5 mm into the wood. As a preservative it is effective for exterior work above and below ground, but the thin layer makes it less useful in practice.
Tung oil seeps into the grain of the wood, giving it a perpetual wet look that highly accentualizes the grain of the wood, commonly referred to as "making the grain pop". Because of this, the color of the wood is slightly darkened, giving the wood a rich, warm color that is very pleasing.
Tung oil provides a relatively hard surface finish that, as long as the surface integrity is intact, provides a waterproof finish that is impervious to dust, alcohol, acetone (nail polish remover), and various acids such as fruit and vegetable acids (orange juice).
Tung oil has a proven history in exterior applications, both above and below the soil level. Though the dried oil is relatively hard, the finish it provides is not the most durable. Tung oil is usually chosen for its aesthetic appeal rather than its wearability.
In its pure form, tung oil is a non-toxic finish that is ideal for surfaces that are expected to come into contact with food. This includes wood cutting boards, salad bowls, salt and pepper mills and any other project imagineable.
The following refers primarily to pure 100% tung oil. Please see the Variations section below for properties of those variations.
As long as the surface bearing the tung oil has not been damaged, tung oil provides the following benefits:
Tung oil produces a mildly disagreeable odor for a few days after it is applied. This odor lessens with time, however some find that it continues for quite some time afterwards. If the tung oil is to be coated with some other finish such as wax, shellac, lacquer or polyeurethane, this smell is no longer noticeable.
Tung oil takes time to dry. Today's high-tech woodworker is often in a hurry, but true tung oil takes its time to cure.
Pure tung oil has relatively poor penetration, and scratches that penetrate the finish can expose the bare wood beneath. This can be compensated for by adding up to 50% turpentine as a thinning agent to improve penetration on the first coat only. Subsequent coats should be done with un-thinned tung oil.
Pure tung oil is difficult to store. Depending on temperature, and exposure to light, the surface of the oil in the container will start to form a film or there will be gummy deposits around the container's edges. Once these symptoms appear, the entire container must be discarded, since the oil will no longer be able to cure properly if applied.
Please note that all these variations on tung oil go through processes that render the finish toxic. Only pure tung oil which has not been thinned can be considered non-toxic. Please be careful.