I am thinking about using some White Bohining fletch lac to make some solid white shafts.  Should I cover them with clear after the white or will they be sealed already?  I have never used Bohning before so I don't know the full properties of it yet.

I'd use the clear/blue(won't yellow on ya) over the white, although I haven't tried full length dipping. I've dipped white caps without clearing and they still seem fine, 10-15 years after making them. I don't think it's necessary to clear over the white as it should be sealed already, but it sure won't hurt and it'll add some weight...plus it will probably help with target burn to clear over the white.

Interesting question.

Ditto what wooddamon1 said

I never clear dip over the colors and think it's fine. Plenty tough finish!

I would clear coat the entire wood shaft, lightly steel wool, clear coat again. Thin the clear coat out first.

Then...just dip the shaft with the white paint, making sure you thin it out properly for good run off. Thin it out so all you need is one good white coat. Been using Bohning  for years...love the finish.