Hmm... ok, this may be a toughie!! Firstly im assuming from your tech talk your creative trained??? so then im assuming you know about your mix ratio and knowing when your bead is the right consistancy.
i may be wrong but from my experience in 6 years, and from what i have seen my students do, your bead could possibly be too dry by the time it gets to perfecting your corners... your bead is 'set' in 3 minutes from bead creation so maybe you may need to work slightly quicker to get it right before it is unworkable.
when you place your bead on the nail and allow it to settle, if it drops
50% or more and/or has a ring of liquid around the bead, it is
too wet.
if it drops hardly at all and has powder still on the bead that is unabsorbed then it is
too dry.
with the correct mix ratio
(1½ parts liquid to 1 part powder for retention +) it should drop around
25% and no more than
25%, it should keep a perfect dome shape whilst settling too.
Avoid overworking your product, i.e. overly pressing and smoothing. once your bead has been placed and settled, press gently in the centre of the bead and lift brush move slightly to the left (or right, whichever you prefer) and press and lift again. (DO NOT PAT! YOU WILL PULL AIR BUBBLES INTO YOR PRODUCT...) ensure you do this until you reach the edge of your tip then smooth at the side only to seal your bead. come back to start from the middle again, and press and lift till you reasch the opposide side and smooth. feather smooth over the bead working quickly from one edge to the other, then drain excess monomer from your brush and tuck your smile line to perfect smile and corners... if it is the case that your bead has partially 'set' it will rather stick to your brush rather than the tip!!
I hope this helps and i havent confused you. if your unsure of what ive explained, let me know and i'll try to help.
xxx