Flexible CA, I use it on every Pen I make that has wood, even the ones with Acrylic and Wood, it is a pain in the butt to do sometimes but is well worth it, the Finnish is very deep and thick looking, takes about 2 weeks to completely cure.
The way you apply it is by putting your lathe on the slowest speed you have, then hit the blank with Activator for about 2 sec. what this does is to allow the CA to dry from the inside out, next you place on of those small bags that come with your pen kit over your index finger on the bottom side of the blank, take the Flexible CA over the top of the blank and lay down a 1/8 bead of CA moving down the Blank, once you get to the end stop applying CA, now that you finger and go back down the Blank in the other direction smoothing out the CA. the smoother you get it the better, when the CA starts to set you will feel it starting to pull the bag off your finger, at that time stop smoothing , now hit it with Activator again to fully set the CA, repeat this steep 7 more times if you get a little carried away with the 1/8 bead you can use lees coats, after awhile you will get the hang of this.
Once you have applied all of the coats, hit it one more time with Activator and make sure it cover the entire Blank, now with a Skew come back and smooth out the Finnish, you will notice the part you cut down will now be dull, the object is to make the whole blank dull without cutting thru to the wood, a lot of time I will get it about 90% dull and then I will take 400 grit sand paper the rest of the way, once the entire Blank is completely smooth switch to Micro-Mesh and polish to 12000 and then put a couple of coats of Ren Wax.
I would wait 48 Hours before assembling the Pen so the CA does not separate from the blank.
A lot of work but the Finnish will look like it was dip...
