QWET: Quick Wash Ethanol Extraction, Step by Step

QWET is a 20 second to 3 minute wash of decarboxylated, deep-frozen cannabis in ethanol chilled to -18C (0F) or colder. The short contact time and the cold pull cannabinoids while leaving most chlorophyll behind.

Given time and warmth, ethanol dissolves cannabinoids, terpenes, chlorophyll, waxes, sugars and plant salts indiscriminately. Cold slows the polar and high molecular weight material far more than it slows cannabinoids. A quick wash exploits that gap, giving a pale gold oil instead of the dark green-black of a long soak. If you are new to solvent work, read the beginner’s guide to extractions first.

What is QWET and how is it different from a normal tincture?

QWET stands for quick wash ethanol technique. Three things define it. The material is decarboxylated first, then frozen. The ethanol is frozen to at least -18C (0F), ideally -25C (-13F) or lower. Contact time is seconds to a few minutes, never hours.

A conventional tincture does the opposite: room-temperature or warm alcohol, long contact, sometimes weeks. That pulls more of everything, including chlorophyll, which tastes grassy and darkens the oil. The trade-off is covered in why time matters in cannabis extractions.

QWET is not different chemistry. It is the same solvent run deliberately inefficiently. You give up yield to buy purity.

Those recovery figures are practical ranges reported by home producers, not lab numbers, and they vary with grind, moisture and agitation. Treat them as directional. If total recovery is what you want, RSO and FECO are the correct tools and the dark colour is the point, not a fault. See is there oil in RSO and FECO.

Why must the material be decarboxylated before the wash?

Because ethanol does not decarboxylate anything. It only dissolves what is already there.

Raw cannabis holds cannabinoids mostly in acid form: THCA, CBDA. Heat drives off a carboxyl group as CO2 and converts them. Skip this and you get an acid-form extract, which is legitimate but not what most people mean by QWET oil.

Decarboxylate at 110C to 120C (230F to 248F) for 30 to 45 minutes, thin layer, covered dish. Higher temperatures work faster but cost terpenes and degrade THC to CBN. Full detail is in the complete guide to cannabis decarboxylation.

Decarb first, cool, then freeze. Never wash warm material with cold solvent: it warms the ethanol on contact and the mechanism collapses.

What ethanol should you use, and at what proof?

Use food-grade ethanol only. Never isopropyl alcohol. Never denatured alcohol. Both contain compounds that are not safe to consume.

Proof matters because water content changes what the solvent picks up. Water carries chlorophyll, sugars and plant salts into the extract. Less water means a more selective wash.

A longer comparison of grades is in the best alcohol for making FECO, and the same reasoning applies here. One practical note: 95 percent ethanol freezes near -114C (-173F), so a domestic freezer at -18C (0F) chills it hard with no risk of solidifying.

How do you actually run a QWET, step by step?

Quantities below are for 28 g (1 oz) of decarboxylated material. Scale linearly.

You will need: 28 g decarbed cannabis, 250 to 350 ml of 190 proof food-grade ethanol (if you are evaporating in the Herb Lab, run it in two passes, each below the 250 ml MAX line), a wide-mouth glass jar, a stainless mesh strainer, a coffee filter or 25 micron bag, a Pyrex evaporation dish, a silicone spatula, a timer, nitrile gloves.

Step 1 – Decarboxylate. 110C to 120C (230F to 248F), 30 to 45 minutes, thin layer, covered. Cool to room temperature.

Step 2 – Break the material up. Coarse, not powder. Pieces roughly the size of a grain of rice. Powdering drags fine particulate through the filter.

Step 3 – Freeze both, separately. Cannabis in a sealed jar, ethanol in a separate sealed bottle. Minimum 24 hours at -18C (0F) or colder. This is the single most important step. Do not shorten it.

Step 4 – The wash. Work fast. Pour the frozen ethanol over the frozen material at roughly 10 ml of solvent per 1 g of material. Swirl gently, do not shake. Start the timer.

Step 5 – Time it. 60 seconds is the standard first wash. Under 30 seconds is very clean but low yield. Beyond 3 minutes the chlorophyll arrives in quantity. The optimum is genuinely disputed: reported sweet spots run from 20 seconds to 3 minutes, and colder solvent tolerates a longer wash.

Step 6 – Strain immediately. Pour through the mesh strainer into a clean vessel. Do not squeeze the material. Squeezing forces chlorophyll-loaded cell contents through.

Step 7 – Optional second wash. Refreeze the material for 20 minutes, then run a second 60 second wash with fresh frozen ethanol at 5 ml per 1 g. Collect it separately. It is darker and weaker. Combine it or keep it as a lower grade.

Step 8 – Polish filter. Pass the wash through a coffee filter or 25 micron bag. Allow 10 to 30 minutes by gravity.

Step 9 – Evaporate. Pour into a wide, shallow Pyrex dish to maximise surface area. Evaporate outdoors, or under a fume path with forced airflow. No electric hob element, no gas flame, no ignition source. A warm water bath at no more than 60C (140F), outdoors, speeds it up. Most of a 300 ml wash is gone in 2 to 6 hours.

Step 10 – Finish. When the oil is thick and glassy it is close. Residual solvent leaves last. A vacuum chamber at 40C to 50C (104F to 122F) is the reliable finish. Without one, extend airflow evaporation by several hours.

Expect roughly 3 to 5 g of oil from 28 g of good flower, depending on starting potency. Yield maths is covered in cannabis oil extraction efficiency.

What are the safety rules for working with ethanol?

Ethanol is flammable. Its vapour is heavier than air, so it pools at floor level and travels along surfaces to find an ignition source metres away. This is the most misunderstood fact in home extraction.

• No open flame. No candles, no pilot lights, no smoking in or near the space.
• No electric stove element. A glowing element is an ignition source, as is the thermostat spark inside a domestic oven or a fridge compressor at floor level.
• Never heat a sealed vessel. Ethanol vapour expands. A capped jar under heat becomes a pressure vessel.
• Ventilate properly. Cross-ventilation, or work outdoors. A closed kitchen with a window ajar is not ventilation.
• Evaporate outdoors or under a fume path. Vapour volume, and therefore risk, peaks here.
• Food-grade ethanol only. Never isopropyl, never denatured, never methylated spirits, for anything ingested.
• Keep a suitable extinguisher to hand. Alcohol fires are class B. Water spreads them.
• Gloves and eye protection. Cold solvent and concentrated oil are both unpleasant on skin.

If any part of this makes you uncomfortable, that instinct is correct. Do not proceed.

How do you dose and store the finished oil?

Store in a sealed amber glass jar in the fridge or freezer. Cold and dark slow the oxidation of THC to CBN. Label it with the date and the material weight.

Potency is unknown without testing, so work backwards from inputs. From 28 g at an assumed 18 percent THC, at 75 percent recovery, you have roughly 3.8 g of THC in whatever oil you collected. Run your own numbers with the potency calculator rather than guessing.

For anything you plan to eat, read the complete edible dosage guide first. QWET oil is concentrated, and a portion the size of a grain of rice can be a substantial dose.

Frequently asked questions about QWET

Is QWET the same as QWISO?

No. QWISO uses isopropyl alcohol. The technique is analogous but isopropyl is not safe to ingest and QWISO products are generally not intended to be eaten. QWET uses food-grade ethanol.

How long should the wash actually be?

60 seconds is the common default. The usable range is 20 seconds to 3 minutes. Shorter is cleaner and lower yield, longer is darker and higher yield.

Why does my QWET oil still look green?

Almost always because something was not cold enough, the wash ran long, the material was squeezed during straining, or the material was ground too fine.

Can I use vodka?

No. At 40 percent ABV it is 60 percent water, it will not chill properly, and the water carries chlorophyll and sugars straight into the extract.

Do I have to decarboxylate first?

Only if you want active THC in the finished oil. Skipping decarb gives you an acid-form extract instead.

Can I reuse the washed material?

A second 60 second wash recovers a useful amount. A third wash returns very little cannabinoid and mostly plant material. Two washes is the practical limit.

Is a vacuum chamber necessary?

Not to make the oil, but it is the only reliable way to remove residual ethanol. Without one, extend evaporation time and accept some residual solvent.

Before you start

Ethanol vapour is heavier than air and travels. Evaporate outdoors or under forced airflow, never near an element or a flame. Start with a dose far smaller than you think you need, wait at least two hours before taking more, and keep the oil labelled and away from children and pets.

The NOIDS Herb Lab is the extraction device used across the NOIDS method guides.