What voltage should I use to heat a 36 gauge nichrome wire to 100 degrees Fahrenheit?
It depends entirely on how much heat is removed by the surroundings. In a vacuum, with a small voltage across it, it will continue to rise in temperature until it nearly melts. At which point the light radiation given off starts to be a source of energy removal and the &quot;filament&quot; kind of temperature stabilizes.
In other words, by removing heat (air, flow of air etc.) it keeps the the object being heated to a finite and controllable value but, only if you understand the thermal equations for the heat being removed and, for a complex shaped material that isn't an easy thing to speculate on.
However, if you know the resistance of the wire at the temperature you want, a control system can be made to keep the wire at the right temperature within certain limits of air-movement.
Or, use a separate temperature sensor to control temperature.