In anticipation of spring sales, I've built a few paddles. I like to use western red cedar for the body, with black locust reinforcement. Its finished with my own version of "boat soup", a traditional mixture of oil, pine tar, turpentine, and whatever else the builder thinks appropriate. "Soup" is an apt moniker, given the propensity of cooks to throw everything but the kitchen sink into soup.
I use raw tung oil, turpentine, real pine tar from pine trees, and a dash of Japan drier. I plan on experimenting with adding a little beeswax too.
It comes out nice, but not as pretty as if the pine tar was omitted, which gives it a slightly dirty look. I think its worth it for the protection pine tar provides.
Some rationale regarding materials used in my paddles:
Western red cedar: Light weight, comes in clear, straight lengths, rot resistant, strong enough.
Black locust: Very strong, absurdly resistant to splitting, rot resistant.
Raw tung oil: Very tough finish, non toxic, natural. From the seed of the tung tree.
Pine tar: Excellent protection, smells great, made from "dry distillation" of resinous pine roots.
Real turpentine: Non petroleum derived thinner, somewhat renewable, distilled from pine resin. My friend Rick loves the smell.
Japan drier: Nasty stuff, but necessary for the finish to dry faster than a month or more.
Epoxy (and sometimes thickened polyurethane): Plastic glue, basically. Plastic, nuff said. But its waterproof.
Beeswax: Natural, waterproof, with propolis, which has antimicrobial properties.
With its constantly reversing and interlocking grain, black locust is among the most challenging woods to work, even in the small parts I use for paddles. I'm constantly fighting tearout. In contrast, there's nothing easier to work than clear, straight, western red cedar, and I'm lucky to live in the heart of its natural geographic range, where its plentiful.