Does your herb vaporize between tokes on a portable
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that depends on the vaporizer. Vapes that use conduction (a metal element that glows red hot) and have it in the herb chamber tend to keep vaporizing between tokes while the metal is still hot.
Convection vapes have the heat source upstream and it heats air, which then flows into the chamber to vaporize the herbs. When you stop inhaling, it stops pulling this hot air--vaporizing stops.
And, some vapes are a combination of some convection and some conduction.
To your temp question about the burnt taste at 400 F---that also depends on the vaporizer. I have a miniVAP and Herbalizer, both of which will vaporize at 440 F without any burnt taste.