: I've been researching Tung Oil of late for a different purpose, but wanted to
: let you know that the chinese have used tung oil to water-proof wooden
: boats/ships for many hundreds of years. In pure form it takes a very long
: time to dry, so the new hot thing is to use citrus solvent as a 1:1
: thinner with pure tung oil (China's is reputed to be the best quality),
: get it in there, and layer it in.

The Tung tree is native to China. I don't know if it's being grown in other places (I assume so), but I doubt that there's enough difference between sources of tung oil to make a difference that would matter on a kayak paddle. We're not finishing fine furniture, after all.

: It hardens not by eveporation, but by oxidation,

That is true of all oil finishes and varnishes.

: I'd guess that for weather/waterproofing, you'd want quite a few layers.

Not necessarily. Oil finishes cannot be built up to any significant thickness, so you rapidly reach a point where all you're doing is wiping on oil, then wiping it back off again. For paddles, I find that 4 coats is about as much as I can apply before I'm just wasting my time and tung oil.

: You can also add more later without undoing everything you accomplished in
: the first job. Just a good cleaning.

A thorough fresh-water rinse, followed by a light sanding to remove any burrs, and add some "tooth" to the original finish is all that's necessary to prep for re-oiling.

: Hey, and it doesn't mildew the way linseed is famed.

Correct. While that's not an issue on paddles, it's important for SOF frames.

: Good luck... anyone find a great price on gallons in the U.S. let me know.

I've never seen it in quantities larger than a quart/liter.