Prrl has a write up on here
tl;dr I tried to explain why the additional conduction opportunities between solid lumps that are introduced by light packing works so much better for me in my various vaporisers
here if anyone cares. Like when making espresso, the extraction profile can be controlled by varying the grind and the tamp for any given temperature/machine/bean....
Putting aside the complexities of how different molecules vaporise once heat arrives to warm up a lump of bud, IMHO what little that article states about
heat transfer is grossly oversimplified as if it was written by someone with a limited understanding of the physics.
Fundamentally, it does not account for the very obvious physical fact that hot air cannot flow
through any of those little solid fragments of weed or as pointed out below, the good stuff in the trichome heads sitting in your bowl. Air has to flow
around anything solid. By definition, the physical mechanism we call convection can only transfer heat to a surface directly exposed to the hot air moving past. Convection only happens at exposed surfaces. Conduction is the physical mechanism by which
some of that heat is then transferred toward the cooler interior of the solid pieces. Conduction is the only known physical mechanism for heat to get inside there from the heated surface, to make the material warm enough for the various interesting molecules to break loose and form vapour.
The point is that this remains true no matter what combination of radiation, conduction and/or convection transferred it from the device's heat source to the solid fragments and trichome heads in the bowl. Wherever fragments touch each other, heat can flow from the hotter to the cooler one by conduction. More contact, more efficient conduction so more of the mass in a lightly packed load will reach a higher temperature from any given amount of heat that is transferred from the heat source by any mechanism during a toke, compared to the same load unpacked. Of course, just like espresso, an over-fine grind and/or packing too tight by tamping will choke anything trying to move through the material. It's the balance between them that controls the extraction profile.
It was the swirling but poorly extracted weed in my very first Arizer EQ cyclone bowl tests that made me realise why it didn't work as well as elbow/DDave mod packed loads on that heat source.
With the extremely effective stream of hot air injected by a Freight Train, the need for additional conduction from touching particles is in my experience, less pronounced. It hits hard if you just hold a nug in the way! For me, it hits a little more to my liking with light packing. Everyone has different requirements of course, but I think I understand how the extraction profile is affected for any given heat source and inhalation pattern - earlier and more abundant content of the heavier, less volatile terpenes, that may be stored deeper than the bract surfaces perhaps?
www.themininail.com
