Here's my special technique.  I've noticed that low-viscosity CA penetrates between mineral grains very nicely, but doesn't do a good job (permanently) filling the caps between the grains.  After all, it's not meant to be gap-filling.  Thicker CAs are gap-filling, but they don't reliably penetrate between the grains, as they don't "wet" the surfaces very well.  So my trick is to wet (but not saturate) the mineral grains with thin CA  and then - before the thin CA hardens - add the thicker CA.  The thicker CA readily penetrates and fills the pores, and actually displaces much of the thin, which I then "wick up" with a piece of tissue.

By professional wood turner Don Lindsley:

Check out his web site: www.thewellturnedbowl.com