Nylon jaw pliers will not mar, nick, or mark your precious wires and metal sheets. They are specially manufactured for non-scratch shaping, sculpting, wrapping craft wire, jewelry wire, color coded wires, soft wires. They are also ideal for semi-precious and precious wires.
Not only will the nylon jaws not nick, mark, or damage the wires you are working with, they are also ideal for straightening wires (which work-hardens and strengthens them). Just run the nylon jaws over the wires a few times to straighten and strengthen.
This means that you can now easily undo minor mistakes just by pulling the nylon pliers over your bent wires to get rid of the kinks. And for (semi-)precious wires, you no longer have to suffer the waste of kinked expensive wires.
Being gentle on wire, these pliers and the flat square shape that they have, they are a god-sent in making design bends in your wires. Once you are done, you don't even need to refinish or rebuff the wires.
The nylon jaws will wear out over time. You can get replacement jaws. However you can get strong, durable and yet low-priced nylon jaws pliers so that you can just as easily and as cheaply replace the whole plier.
Nylon jaws have become increasing popular over the recent years. You can now find them in multiple types of pliers. They can be offered as double nylon jaws or single nylon jaw (with the other jaw in metal). Rounded nylon jaws are also available on the market which are very good for forming loops without marring.
Many of the different types of pliers are now offered in the nylon-jaw version as well. You can buy them individually or in kits.
I cannot do without my nylon jaw pliers. I use them at every turn and virtually every time I pick up wire. It feels really good to know they will not mar my wire work and they make straightening and work-hardening my sometimes squiggly wires so easy.