Something else that works great when you are trying to build up a fillet with CYA is baking soda. Put on your CYA then sprinkle some soda on. It cures instantly.

I know I'm sounding like the MOM here, but this is important. When you are working with CYA always have lots and lots of ventilation or preferably wear an organic vapor respirator mask. Many here on RCU (do a search) including myself have had respiratory problems with using CYA. Be careful.