re: Filling small knots and voids

I’d probably use the medium. Sand up a pile of dust from those boards (so it’ll match), drop in some CA glue to mostly fill the voids, the scoop on some dust and kinda work it into the voids. Don’t be stingy. The glue will soak right into the dust. May need to add some more glu and more dust to top it out. You want it to end up a little proud of your surface, it’s ok if it’s not smooth or is a bit wonky, you just want to make sure there aren’t any gaps. Once it drys, then sand it back. I don’t use activator when I fill voids, just let it dry on its own. 

Some guys will pack the voids with sawdust, then add thin CA across the top to permeate the dust. I think this probably works just fine too, and maybe keeps you from glueing your fingers together! If you do this, something the liquid of the CA will settle the dust down a little and it’ll recess a bit into the void, leaving a hollow that needs to be addressed before sanding back. 

I use the medium for this because the thin is SO thin it finds ways to leak out of the wood sometimes. Anyway, that’s what I do. I’m sure there are a hundred YouTube videos too!!