Tip heats instantly with the push of a button. Use instead of scissors to cut/melt thread close to the beads which also fuses the thread so it won't fray. Here's what Marg has to say about it: I use a Thread Zapper all the time and many teachers recommend them for nymo, Fireline or Wildfire. You can get in very close with the tip and the end of the thread is melted, which prevents it from fraying. I find it's faster than scissors.
The only caution is don't hold the Zapper button down for a long time or it will get so hot that the tip will actually melt and, like a burned-out light bulb, it won't be usable any more. Two or three seconds is more than long enough to cut even heavy Fireline. Battery operated - takes one AA battery, included. Caution. End gets really hot - don't burn yourself.