Hi - I am renovating my barn/garage and had custom carriage doors built using seapel mahogany. Was actually less expensive than fir or any other options.

So now I have the beautiful doors that I know will take some punishment from water - especially at the bottom until I can fix my drainage problem.

I know a bit about finishing but no idea how to protect exterior wood like this. Most likely we will be painting the doors so I could just use a regular oil based stain. However I've seen some chatter about "Cetol" but not sure if that is for a stain and finish vs painted.

Can I use a stain for color, then cetol to seal, then some kind of external finish like poly? If we don't like the look can I just then paint over that?

 

A translucent stain will protect the wood but you'd need to stay on top of recoating it as needed. The same would be true if you just used a spar poly. Primer and paint gives the best protection but might not be the look you want. Coating the backside and top/bottom of the door will give extra protection from moisture.