So, which oak is it?
If it's white oak it needs no filler because the pores are filled (by the tree) with tyloses. That's why it's the choice for wine barrels.
Thats true for the wood under the surface. As you machine the surface with a cutting tool, that tool will pull out some of that material from the surface pores. So even white oak would need some filler.
I did not use anything as a filler. i will do this on the next set. This was my first attempt and there are some small imperfections where I messed up. They did not come out bad just little things I can see that do not show up on camera. The best part of the entire process was seeing the grain come out as i went from rough shaped chink of wood to the final sanding
