During true vaporization, the heating chamber functions similar to a convection oven. The chamber will evenly heat to a controlled temperature that will bake the dry herbs and release their aromas. The dry herbs will then discolor and likely turn brown. If you heat a dry herb vaporizer to it’s highest temperature (typically 430F), the dry herbs can turn to the color black. Dry herbs will not turn to ash. True vaporization is considered a healthier way to vape. If you’d like to learn more about combustion versus convection, please read our in-depth article here.
When you use a vape pen that has combustion, the heating chamber typically has an exposed coil that provides direct heat. The temperature is not controlled and the dry herbs are heated by the touch of the coil. The direct heat will burn the dry herbs and eventually tun them into ash.