glassing on fins with UV resin - problem

I think I finally figured out why I am getting air bubbles along the base of my fins when I am glassing them on.  I glassed on a pair today and everything looked good when I put them in the sun.  I brought the board in after a minute to cut off the excess cloth.  After I did that I noticed air bubbles along the base of the fins.  I pushed on it and noticed that the resin was still really liquid in the fin rope so I guess the little bit of movement when I cut the cloth let some air into the liquid resin along the base.  Now I just need to know how to avoid that.  Any suggestions?  I was thinking of either not cutting off the cloth and just grinding it down with my sander later, or using catalyst instead so that the rope hardens along with the cloth on the fins.  What do the rest of you that glass on fins and use UV cure resin do?  Thanks

Uv with a little catalyst in it.  And let it kick hard before you start poking it…Dats what I do.