We have an old CNC carved sign that came with our property. It is at least 17 years old and has been out in the weather constantly. I think it is oak.
I want to paint the lettering white so that you can actually read it.
I tried painting some of the lettering with a poly oil based white paint and an artist brush. The wood is so porous that it just soaks the paint up and you get almost no color deposit. I'm thinking that I need to seal the wood fairly well with an outdoor varnish like Spar Urethane, and then paint.
I don't think the technique of spraying the whole thing white and sanding off on the flat surfaces would work at all because of all the deep cracking in the wood.
Alternatively, maybe there is a very think paint designed for this exact purpose? Maybe sign painters have a special paint?