End grain glue ups dont work too well here. In that situation, Id personally mechanically fasten it with some brackets and screws, while using epoxy to glue it with some dowels or biscuits. I presume youre doing an L or making a really long straight here. (EDIT: when i say "bracket" thats just a catch all term. I've seen tons of various types of mechanical fasteners for this kind of application, and im pretty sure almost any would be fine in this situation).
Silicone has a strong chance of staining the wood making it difficult, if not impossible to get a uniform finish; sometimes even prevents finish and stains from adhering/absorbing. Epoxy is fully waterproof, and has no such issues. When you go to install your sink, the wood should be finished already so silicone for the sink is acceptable there.
If youre using that baltic birch top from lowes, i wound up doing my parents kitchen with it. Worked amazing, just make sure if youre planning on staining to use a pre stain sanding sealer product first. I admittedly skipped this step at first and holy cow it was STREAKY and i had to sand back and redo it all. I finished with a catalyzed urethane in matte and it came out great in the end.
Good luck, im sure some others will chime in with other ideas too
Last edited by bob493; 11-30-2019 at 02:04 PM.