can I paint barnboard?
Without seeing them, I can't say for sure
But if they are what I'm picturing, you could paint them
It will be a bit of a project, as the surface will be tough to apply paint to
And you'll have to prime them first, with a white-pigmented shellac
That stuff is stinky, you'll need lots of fresh air and a respirator
For application, possibly a big nap roller, and depending on how rough, an exterior brush may work better than a traditional interior brush
Ask at your local Paint Shop (not a paint department in a big box store) what they've got available