Reply by Jack_Isidore

Well, despite the masking, I would still get the mixture high enough up that it gets sanded flat. I think the point is to keep it from embedding intself into the wood surrounding the knot, and being noticeable when the wood is finished.

I won’t be staining the project, just finishing with deft danish oil.

I don’t think the point is to make them invisible, so much as just flat and flush.