Milling cypress, and expanded pvc

hello to all, I am making a plaque out of cypress (1.5"*11.5"*18") with an arched inlay of black expanded pvc. I need to mill the piece down on the bottom where the pvc is. does anyone know how well it takes to sanding, and putting a varnish on. I.E. sanding marks disappearing.

All wood will show sanding swirls, hard wood less than soft but they’ll still be there
Just make sure go up through the grades of grit, 40, then 60, then 80, then 100 etc. You can miss out the occasional grade but not too many. Go up as high as possible, I’ll usually go to 400.
It should be fine to varnish, give it a wipe down with turps/white spirit,. Maybe even give it a light spray with some water to raise the grain, then give it the highest sand again.

its not the wood portion I’m concerned about, I build cabinets as a side job. It’s the expanded pvc that I was concerned about. I just went and passed some 320 over the whole thing and said oh well. will post pics when its done

Ah right, thought you were asking about the wood.