I have the sofits and facias round our house done in black, or it might be called ebony. I did them 6 year ago and they are still good for another couple.
You apply 1 coat of Butinox no 3 which is oil based folowed by 2 coats of no 2 which is water based. Not cheap but lasts better than anything. I got mine from the local hardware shop.
AL.