there's an oil made for outdoors. Mc Clousky (sic)
makes it. Called Out Door Oil. It has UV protection and is just wipe on like lindseed oil. Woodcraft has it online and in their stores. Lampblack is just fine carbon particles.
Use something made for out doors or the wood will turn grey due to the UV rays, but you may want that. Lots of options.

John
Wichita Forest Woodworks


I know you believe you understand what you think I said, but I'm not sure that you realize that what you heard is not what I meant!