as you don't thread clients with broken skin — it's a fairly safe procedure. The biggest thing to be careful of is to make sure the area you're threading is tight, which we'll go over when I show you technique. If the skin isnt tight, there's a good possibility the skin will get caught in your thread and you can nick your client. This literally looks like a 1-2 mm cut in the skin. Your client might have some tiny bleeding, their cut might take a day or two to heal, but with enough experience you'll know within one or two zips if your client is stretching enough.