On all exterior and some interior wood we spray 2 coats of primer which is a flexible undercoat which reduces cracking when there's movement in the wood. It has a high build offering a smooth finish ready for top coat. Has a tanning block which stops 99% knots bleeding through and is microporous which lets the wood breath. 
We use this on exterior windows and doors before fitted.

The topcoat is a water based paint and is made by the same company who makes the primer so the two bond together to produce a top quality finish.
It can be sprayed in any colour and any sheen.