Quote Originally Posted by adizziedoll
actually - not true. As long as you cut the clear plastic inbetween the black heating (zig-zagged), it'll be fine.
Well, you're not supposed to cut it. The little bit of plastic you leave by cutting in between those zig zags could melt away in certain situations and become a fire hazard.

This is directly from Calorique (Flexwatt manufacturer):

When cutting tape: 3” & 4” – never cut through the black stripe. 11” always cut on the cut line.