A dry herb vaporizer works by heating ground herb in a small chamber to a controlled temperature — usually 160–210°C — so the terpenes and cannabinoids in it boil off as vapour while the plant material itself never reaches the roughly 233°C point where it would burn. A heater powered by a battery, the mains or a flame warms the chamber by direct contact (conduction), by hot air (convection) or both, and when you draw, air carries that vapour through a cooling path to your mouth. What's left behind is toasted brown herb, not ash.

That's the whole mechanism in three sentences. Below is the long version, in the order the heat actually travels: heat source, chamber, heating method, temperature, airflow, control — and what's left at the end.

The Whole Process at a Glance

Step	What happens	Where
1. Power	Energy goes into a heating element (or a flame heats a metal tip)	Battery, mains, or butane/induction
2. Chamber	Ground herb sits in a small oven, typically ceramic-coated metal or glass	The bowl / oven
3. Heat transfer	Heat reaches the herb through hot walls (conduction), hot air (convection) or both (hybrid)	Chamber walls and airflow
4. Vaporisation	Compounds whose boiling point is below the set temperature turn to vapour; the plant fibre doesn't burn	Inside the herb itself
5. Airflow & cooling	Your draw pulls air through the herb; vapour cools and condenses into a fine aerosol on the way out	Airpath, cooling unit, stem, whip or balloon
6. Control	A sensor reads the temperature and the controller adjusts power to hold it	Circuit board, buttons, display or app
7. Leftovers	Brown, already-heated herb (AVB) — not ash	Back in the chamber

The Question Sarah Asked That I Couldn't Answer

About six months after I'd switched to vaporising, Sarah asked me something that should have been simple.

I couldn't answer her properly. I could say "it heats instead of burns," but when she asked what that meant — what was literally happening to the plant, where the flavour went, why it made less visible vapour — I shrugged and changed the subject. That bothered me. I work in IT. I'm supposed to understand how things work.

Too late. This is the dissertation, restructured so you can find the bit you need. Apologies in advance for the IT analogies.

The Principle: Cooking vs Burning

In one sentence: combustion destroys, vaporisation extracts.

Light a spliff and the burning tip runs far above 233°C. Past that point the plant material reacts with oxygen, big molecules break apart and new compounds get made — tar, carbon monoxide, and the rest of the list you never asked for. The compounds you actually wanted get partly destroyed in the same fire.

Set a vaporizer to 185°C and you stay well under that line. The terpenes and cannabinoids sitting on the surface of the plant simply evaporate off it, the way water evaporates off a warm pan. No flame. No ash.

My IT version: when you want data off a hard drive, you can plug it in, copy the files and eject it safely — the drive stays intact and you can go back for more. Or you can set the drive on fire and try to read the smoke. Smoking is option two. Vaporising is option one.

The number to remember: 233°C. Below that line, you're cooking and extracting. Above it, you're burning.

Step 1: The Heat Source

Something has to make the heat, and there are three ways vaporizers do it:

• A battery. Every electric portable runs on lithium-ion cells feeding a heating element. The Mighty+ and Venty each carry two internal 18650 cells; other portables use single cells, some removable, some sealed. The battery is why portables have a finite runtime per charge and, eventually, a finite lifespan. The battery and power types explainer covers the differences.
• The mains. Desktops like the Volcano Hybrid plug into the wall. Unlimited power means bigger heaters, more airflow and no battery to wear out — at the cost of staying on the table.
• A flame or induction coil. A DynaVap M7 has no battery at all. You heat its metal tip with a butane torch or an induction heater; a bimetal cap clicks when it reaches vaporisation temperature and clicks again when it cools. The flame never touches the herb — it heats the metal, and the metal heats the herb.

Step 2: The Heating Chamber

The chamber (or oven, or bowl) is where the ground herb sits. Portables usually hold somewhere around 0.15–0.3g; desktops and manual devices vary either side of that. Materials matter because the chamber touches your herb and sits at the start of the vapour's journey:

• Ceramic-coated metal — the Storz & Bickel approach in the Mighty+, Venty and friends. Heats quickly, cleans easily.
• Glass — Arizer's portables use borosilicate glass stems that double as the bowl, so the herb sits in glass rather than against metal. Flavour-first.
• Stainless steel — DynaVap's tips and many budget chambers.

How full and how finely ground the chamber is changes everything downstream. Packed too tight, air can't get through; ground to dust, it falls through the screen and scorches. The herb prep guide is where I admit how long it took me to learn that.

Step 3: The Heating Method (Conduction, Convection, Hybrid)

This is how heat gets from the element into the herb.

• Conduction: the chamber walls get hot and heat the herb touching them, like a frying pan. Fast and simple, but the herb against the wall cooks harder than the herb in the middle — hence stirring.
• Convection: air is heated as it passes the element and then flows through the herb, like a fan oven. More even, but heat only really moves when air does, so your draw matters. The Volcano Classic is pure convection.
• Hybrid: both at once. The walls pre-warm the herb and heated air evens out the extraction during the draw. Storz & Bickel's patented system in the Mighty+, Venty and Volcano Hybrid works this way; Arizer's current portables are hybrids that lean heavily on convection.

Which is best? The honest answer after years of being a convection snob about it: implementation beats category. I've done the whole argument in Conduction vs Convection, so I won't repeat it here.

Step 4: Temperature — What Boils Off, and When

This is the heart of it. Every compound in the plant has its own boiling point. Below that temperature it stays put; above it, it becomes vapour. So the number on your dial doesn't just change how much you get — it changes which compounds are in the vapour.

These are the figures we use across the site (from the temperature guide and the editorial team's terpenes and temperature piece). Treat them as approximate: they're lab values for pure compounds, and a packed chamber doesn't behave like a lab flask.

Compound	Type	Approx. boiling point	What it brings
CBG	Cannabinoid	Mid-150s°C	Present from the first draws
α-Pinene	Terpene	~155–160°C	Fresh, piney
THC	Cannabinoid	~157°C (stronger delivery across 170–210°C)	The main active compound
CBD	Cannabinoid	~160–180°C	Broad band; largely available by ~180–185°C
Myrcene	Terpene	~166–168°C	Earthy, musky, fruity
Limonene	Terpene	~176°C	Citrus
Terpinolene	Terpene	~185°C	Herbal, piney, citrus
CBN	Cannabinoid	~185°C	Heavier; joins the vapour in the upper-middle range
Linalool	Terpene	~198–199°C	Floral, lavender
CBC / THCV	Cannabinoids	~220°C	Only meaningful at the top of the range

Two terpenes are missing on purpose. Published boiling points for caryophyllene and humulene disagree wildly between sources, so we don't pin a number on them. The editorial piece explains why.

Put together, that gives you three rough bands:

• 170–185°C — the light, volatile terpenes and the early cannabinoids. Best flavour, lighter sessions.
• 185–200°C — the bulk of the extraction; heavier terpenes like linalool arrive. The all-rounder range.
• 200–210°C — the heavier compounds, denser vapour, and flavour starting to fade.

Above about 210°C, returns fall off fast. From 220–230°C the plant starts to break down from heat (pyrolysis) and you begin creating some of what you bought a vaporizer to avoid. Combustion proper starts around 233°C. My hard ceiling is 210°C, and I spent three weeks at maximum temperature learning why.

Decarboxylation: why heat is needed at all

Raw herb mostly contains THCA, the acid precursor, rather than THC. Heat knocks a carboxyl group off the molecule (releasing CO₂) and converts it — a process called decarboxylation. It starts around 104–115°C and speeds up as temperature rises, so at normal vaporising temperatures it's effectively complete. Combustion overshoots that window by hundreds of degrees. It's using a blowtorch to poach an egg.

Why your 185°C isn't my 185°C

The display shows what the sensor reads, usually near the heater — not necessarily what every bit of herb is experiencing. Research the temperature guide cites found well-designed devices holding within about 10% of their set value, and simpler ones varying far more. Chamber design, pack density, grind, room temperature and draw speed all shift the real number. That's why I tell people to find their setting by taste and by the colour of the leftovers, not by chasing a figure off someone else's device.

Step 5: Airflow and the Cooling Path

Vapour doesn't leave the chamber on its own. Your draw pulls fresh air in through an intake, through (or past) the heater, through the herb, and out towards the mouthpiece. That airflow does two jobs: it carries the vapour, and in convection-heavy devices it's the thing delivering the heat in the first place.

That's why draw speed matters so much. Pull too hard and you drag in more air than the heater can warm, the herb cools, and you get thin, wispy vapour. Draw slowly — long, gentle sips, the kind you'd take from a hot cup of tea — and the heater keeps up. Some devices, like the Venty, let you adjust the airflow resistance to suit.

On the way out, the hot vapour cools. As it cools, some of it condenses into tiny droplets — which is why vapour looks thinner than smoke and why it disappears faster in moving air. The cooling path decides how comfortable the draw feels:

• Cooling units (Storz & Bickel portables) route the vapour through a longer internal path before the mouthpiece.
• Glass stems (Arizer) cool the vapour along the length of the tube, and longer stems run cooler.
• Balloons and whips (desktops) give vapour plenty of distance and time to cool before you inhale.
• Water pipes, for devices with compatible stems or adapters, cool it further still.

Everything in that path is something the vapour touches, which is why materials matter. The editorial team covers that properly in Materials & Airpath Safety. It's also where the gunk collects — resin condenses in exactly the places vapour cools. The cleaning guide tells you where to look.

Step 6: Battery, Sensors and Control

A vaporizer's circuit board runs a simple loop, hundreds of times a session: read the temperature sensor, compare it to your setting, add or cut power to the heater. That feedback loop is what separates a vaporizer from a hot plate — and it's where a lot of the difference between cheap and well-engineered devices lives.

How you talk to that loop varies:

• Degree-by-degree control on the device, with a display showing the actual temperature (Mighty+, Venty, Solo 3 V2).
• Presets — a handful of fixed steps, sometimes with finer control through an app.
• No electronics at all — the DynaVap's click cap is a mechanical temperature signal, and your technique with the flame is the controller.

The controller also decides the heating mode. Session devices hold the chamber at temperature for several minutes; on-demand devices heat only while you're using them. Some, like the Solo 3 V2 and Arizer Go SRT, do both. That's a lifestyle choice more than a technical one — see Session vs On-Demand.

What's Left Afterwards: AVB

With smoking, the leftover is ash. With vaporising, it's AVB — already vaped bud — and its colour is the best diagnostic you've got.

What you see	What it means
Light to medium brown	Vaporising properly. Compounds extracted, plant toasted but not burnt.
Dark brown (at higher temps)	Still fine — just extracted harder.
Patchy: dark at the edges, green in the middle	Uneven heating. Stir, grind finer, or pack more evenly.
Black, ashy, crumbly	Combustion. Too hot, or a device fault. Turn it down.

Because the leftovers have already been heated past the decarboxylation window, they still contain some already-activated compounds. What people do with that is covered in The Lazy Person's Guide to AVB.

Why This Isn't How Other "Vapes" Work

Everything above applies to dry herb vaporizers only. A nicotine vape heats e-liquid on a wire coil. A concentrate device — Puffco's Peak Pro, Proxy and Pivot, for instance — heats extracts in a hotter chamber built for a completely different job. Same verb, different physics. If you're still working out which kind of device you're looking at, start with What Is a Dry Herb Vaporizer?, and the dry herb vs extracts vs e-liquid explainer covers the chemistry. The question of what vapour means for your lungs is its own article: Is Vaping Healthier Than Smoking?

Frequently Asked Questions