Tung Oil

After sanding the teak decking about a month ago I began to think about finding something that would protect the decking and prevent it from going grey.  The few products available in the boat shops seemed expensive with little information about what was actually in the material.

During an internet search I kept seeing references to tung oil, as though the percentage of tung oil was the barometer of efficacy.  That led me to a look at pure tung oil and for various reasons concluded that it was worth a try and located a supplier in the Perth area: Carbatec at 1/168 Balcatta Rd Balcatta. I elected to purchase 4 liters rather than 1 liter of "Oreganoil" tung oil for the usual reason that a 4-liter can is much more cost effective than a1-liter can.

The use of pure tung oil seems to be very rare among the local boating set so for us it would be a big learning experience.  I write "us" because Bruce's wife "Dolphie" wanted to work with me to pick up a new skill. 

We decided to use the teak work over the anchor well for our first experiment.  We laid down a coat of pure tung oil which turned out to be a mistake because it did not dry even overnight.  I did some more research and learned that the name of the game is to get as much penetration into the wood as possible by diluting the initial (or all) coats.  I made another trip to Balcatta and purchased 4 liters of Oregaoil "Citrus Turpene" which is the recommended solvent for various reasons.

The next day we used a mixture of 50% tung oil and 50% citrus turpene and got excellent results both in salvaging the initial work over the anchor well and with new section of teak in front of the companionway and the back seat in the cockpit.  On the new sections the mixture was absorbed quickly and was dry within the 20 minutes stipulated by one web site.  The next day we laid the second 3rd coat on the anchor well cover and the 2nd coat on the new sections.  On Friday morning we laid the third and final coats on the new sections.  We had discussed whether or not to use undiluted oil on the last coat as Carbatec had advised but took Bruce's advice to keep using 50-50 solutions until we were happy with the result.


The pure teak oil and thinner are obscenely expensive (but what isn't in the boating world?), but material has two thing going for it: (1) the oil and thinner go an awfully long way, (2) there is the prospect of the one treatment lasting a long time. 

Knowing what I know now, 1-liter cans would have probably been sufficient but the material will store well and I have now probably a lifetime supply without ever having to chase down the material again.

Regarding durability, Wikipedia states "The Chinese have used tung oil, also known as China wood oil, for at least 2500 years for building waterproof boats and paper parasols, wood finishing, wood waterproofing, caulking, inks and paint." Another site states "The oil penetrates into the wood, providing a relatively hard surface that repels water, giving it a waterproof finish. Another bonus is that tung oil seeps into the grain of the wood making the grain pop. ... When tung oil is not thinned, in other words, its 100% tung oil, it's a non-toxic finish." (Note that the "citrus turpene" that we are using is also non-toxic other than the wonderful citrus scent attracting bees to the boat in just minutes.)  The Carbatec site states:  "Tung oil is one of the few oils that are classified as ‘drying oils’. Other oils that fall into this category are linseed, walnut, soybean and poppyseed. A drying oil is an oil that hardens to a tough film, not through evaporation of the solvents as many finishes do, but rather they undergo a chemical reaction when exposured (sic) to air."

(Caveat emptor: One can of remarkably cheap deck oil stated "Contains pure tung oil" which is not very useful if the percentage of this pure tung oil is not stated.)

Now that I feel confident with tung I expect to treat the cockpit floor and seats with little difficulty.  All I will  require is three successive days without rain.