Hi. I am a complete beginner when it comes to woodworking. I bought a black walnut slab almost a year ago and it has been haunting me ever since. This slab is meant to become a free standing countertop/long table.
Upon arrival I began sanding it beginning with coarse grits, working all the way up to 320. I decided I wanted to keep the bark on to keep the color contrast. Controversial I know, especially because even from the beginning I noticed small potato-bug-like beetles ending up on the ground beneath the slab accompanied by small piles of sawdust. I sanded the top and bottom probably to 180 before I filled some cracks, holes, and crevices with epoxy, the west systems stuff. By the way this is over the coarse of up to 5 months at this point, I ran into many issues and wasn't sure how to solve them so this slab stayed idle for weeks at a time sometimes. Over the winter it remained in my attic, I sanded a few times, and also began smoothing out the bark on the sides.
Throughout this whole time, holes would pop up from those critters, mainly at the joining of the bark and the wood, although since then small holes have shown up elsewhere in the wood. I finally decided to just finish it in the hopes of suffocating the bugs.
After sanding to 320 I decided to poly it using a water-based Miniwax polyurethane (polycrilic), clear satin. I didn't want to use stain of any sort as I only wanted to bring out the natural color of the walnut. I've put on between 5 and 10 coats on both sides, sanding lightly between every few coats until I began using a special water-specific applicator which left it smooth enough.
Holes! More holes kept appearing, so I injected the poly into them if they were large enough, some on the bark, some on on the wood surface. Since then it has stood idle for a week or so, then another coat or 2, then more holes, and this process keeps repeating.
Sorry for the length, it's been about a year and I wanted to detail the process so I could get some specific advice. I need the bugs to die since they keep affecting my finishing process. Once they are gone, a few more coats to fix it up and I'll be set.
Also, at some points during the finishing process poly has dripped onto the top side, creating small bumps of extra poly. These, I've found, are difficult to sand out, and sanding affects the the surrounding area, scratching it up when I only intend to get rid of the bumps. Any advice here?
Eventually I plan on drilling holes in the underside for 3-4 hairpin legs.
Pictures of the slab, and examples of holes and rough patches attached. Having trouble attaching all of them, more to come.
Thanks for any advice and insight!