Why the temperature matters more than the solvent
Ethanol dissolves nearly everything in the plant. Cannabinoids, terpenes, chlorophyll, waxes, sugars and water-soluble compounds all come across if the conditions permit it. That is the problem the technique has to solve.
Chilling the solvent is the solution. At low temperature, chlorophyll and several of the other undesirable components become far less soluble, while the compounds of interest remain available. The temperature is the whole of the selectivity.
This page covers what ethanol extracts, what cold changes, how contact time affects the result, what happens to the solvent afterwards, what remains in the product, and how the route compares with the alternatives.
⚠️ Scope. This page describes a process and what can be verified from documents. It does not describe what a product does to a person, gives no amounts, and does not replace a healthcare professional.
🔴 What ethanol dissolves
The compounds of interest
Cannabinoids and terpenes dissolve readily. This is why the solvent works at all and it is the easy part.
Chlorophyll
It dissolves too, at ordinary temperatures, and it carries a strong green colour and a vegetal character into the extract.
Waxes and lipids
Plant waxes dissolve at warmer temperatures and precipitate when chilled. They are the reason winterisation exists as a separate step.
Water-soluble material
Ethanol is miscible with water, so anything water-soluble in the plant can come across. Sugars and plant acids among them.
Why cold changes the outcome
The solubility relationship
Solubility generally falls with temperature, and it falls at different rates for different compounds. That differential is what cold exploits.
What becomes less soluble
Chlorophyll markedly, and waxes substantially. Both largely stay in the plant material rather than entering the solvent.
What remains available
The cannabinoids, which remain sufficiently soluble at low temperature for the extraction to work.
The consequence
A cleaner extract requiring less refinement afterwards. It is a single-variable improvement with a large effect.
The operating temperature
The range in use
Well below freezing, typically maintained by chilling the solvent before contact and keeping the material cold throughout.
Why colder is generally better
Selectivity improves as temperature falls, up to the practical limits of the equipment and of ethanol’s own behaviour.
The equipment implication
Chilling capacity is the principal capital requirement. It is what distinguishes a cold ethanol operation from a warm one.
What warm ethanol produces
A dark green extract carrying chlorophyll and waxes, requiring substantial refinement to become saleable.
Contact time
Why it matters
Longer contact extracts more of everything, including the compounds that cold was meant to exclude. Selectivity degrades with time.
The practical approach
Brief contact, sometimes measured in minutes rather than hours, followed by immediate separation of solvent from material.
What a long soak produces
Higher yield and a considerably dirtier extract. It is a trade with the same shape as every other in this category.
The operational challenge
Handling large volumes of chilled solvent quickly. It is a logistics problem as much as a chemistry one.
🔴 Removing the solvent
The principle
Ethanol boils at a modest temperature and can be evaporated under reduced pressure, which lowers that temperature further.
The equipment
Rotary evaporators at small scale, falling-film evaporators at larger scale. Both recover the solvent for reuse.
What the temperature costs
Even under reduced pressure, evaporation removes volatile compounds along with the solvent. The aromatic profile suffers.
What remains
Residual ethanol, at a level depending on how thoroughly the removal was carried out. This is what the residual solvent panel measures.
The residual solvent question
The classification
Established guidance on residual solvents groups them by known risk. Ethanol sits in the least restrictive category, with a correspondingly higher permitted level.
What that means practically
Ethanol residues are permitted at levels far above those allowed for hydrocarbons. Compliance is easier to achieve.
Why the panel still matters
Because permitted is not the same as absent, and because the figure indicates how thoroughly the removal was done.
What to look for
The ethanol row on the residual solvent panel, with the threshold stated. Its presence is expected on this route.
Winterisation
Whether it is needed
Where the extraction ran warm, yes. Where it ran cold, much of the wax stayed in the plant material and less remains to remove.
How it is done
Dissolving the extract in ethanol, chilling it so the waxes precipitate, and filtering. It is essentially the cold step applied afterwards instead of during.
The relationship to cold extraction
Cold extraction is winterisation performed during the process rather than after it. That is the clearest way to understand what the technique achieves.
What it costs
Additional ethanol, additional handling, and additional loss of volatile compounds. Doing it during extraction avoids the second round.
The colour question
What a cold extract looks like
Amber to golden, depending on the material and the refinement. Substantially lighter than a warm extract.
What a warm extract looks like
Dark green to nearly black, from the chlorophyll that came across. It requires decolourisation to become saleable in most formats.
Decolourisation
Passing the extract through adsorbent media to remove pigments. It works and it removes other things along with the colour.
What to infer from colour
A light extract suggests cold extraction or subsequent refinement. A dark one suggests warm extraction and minimal processing.
Yield compared
Against carbon dioxide
Higher, generally. Ethanol is a more aggressive solvent and recovers more from the same material.
Against hydrocarbons
Comparable to somewhat lower, depending on conditions. Both are efficient.
Against mechanical routes
Substantially higher. Any solvent recovers material that mechanical separation leaves in the plant.
What determines it
Temperature, contact time, solvent-to-material ratio, and the number of washes. All four are adjustable.
The scale advantage
Why it dominates commercially
Ethanol systems handle large volumes with equipment that is straightforward and comparatively inexpensive. It is the volume route.
The comparison with pressure equipment
No pressure vessels, no certification of that kind, and considerably lower capital cost for a given throughput.
The consumable cost
Ethanol is recovered and reused, with losses each cycle. It is an ongoing cost rather than a one-off.
Where it sits
The route for bulk production. Most volume extract on the European market comes through it.
Safety considerations
Flammability
Ethanol is flammable, and large volumes of chilled solvent require appropriate handling, ventilation and electrical specification.
The regulatory dimension
Facilities handling flammable solvents at scale fall under industrial safety rules independent of food law.
Why this matters commercially
It excludes improvised operation, though less absolutely than pressure equipment does. Small-scale ethanol extraction is technically simple and genuinely hazardous.
What a buyer sees of it
Nothing. It is context about who can plausibly operate at scale rather than a product characteristic.
What the extract contains
Before refinement
Cannabinoids, terpenes in reduced proportion, some residual waxes and pigments depending on temperature, and residual ethanol.
After winterisation and filtration
The same without most of the waxes and with reduced pigment. This is where many products intended for sale end up.
After distillation
A purified fraction with the aromatic profile removed. Frequently re-aromatised afterwards, which belongs on the ingredient list.
What the label should distinguish
Full spectrum, broad spectrum and distillate are different products. The route does not determine which, and the refinement does.
Contaminants and concentration
What concentration does
It multiplies everything that came across, including pesticide residues soluble in ethanol.
Why ethanol is particularly relevant here
It is a broad solvent. Compounds that a more selective route would leave behind can come across in an ethanol extraction.
What the certificate should cover
Pesticides, heavy metals and microbiology on the finished product. The breadth of the solvent makes the first of those more consequential.
The common gap
Testing the input rather than the output. The two are different products with different figures.
What the technique cannot do
Improve poor input
It extracts what is there, broadly. Contaminated material gives contaminated extract, concentrated and with a wide range of compounds carried across.
Preserve the aromatic profile fully
Solvent removal requires heat, even under reduced pressure. Volatile compounds are lost at that stage regardless of how cold the extraction was.
Achieve carbon dioxide selectivity
Ethanol is a broader solvent by nature. Cold narrows what it takes and does not make it selective in the way pressure tuning does.
Substitute for testing
Every panel that matters on any concentrate matters here, and the residual solvent panel is expected rather than optional.
Reading a product description
What is usually stated
That ethanol was used, sometimes with the cold aspect emphasised. Both are accurate as far as they go.
What is usually absent
The temperature, the contact time, whether winterisation followed, and what refinement was applied.
The questions that fill the gap
What temperature, and what refinement. Two questions covering most of what the description omits.
What a specific answer indicates
Someone operating the process. Vague answers indicate a step removed, which is worth knowing.
Comparing the routes honestly
On yield
Ethanol and hydrocarbons lead, carbon dioxide follows, mechanical separation is far behind.
On residue
Mechanical introduces nothing. Carbon dioxide leaves nothing where no co-solvent was used. Ethanol and hydrocarbons both require verification.
On selectivity
Carbon dioxide leads through pressure tuning. Cold ethanol is second. Warm ethanol is the least selective.
On capital cost
Mechanical is lowest, ethanol next, carbon dioxide highest for a given throughput.
Preparing the material
Why it matters
The solvent has to reach the glands. Whole flower extracts less completely than material that has been reduced, and particle size affects both yield and contact time.
The moisture question
Ethanol is miscible with water, so moisture in the plant material comes across into the solvent. Material is generally dried below the range that would suit storage.
What excess water causes
It carries water-soluble plant material into the extract and complicates the solvent removal, because water and ethanol do not separate readily by evaporation.
The practical consequence
A step that looks like a detail determines a good deal of the result. Material preparation is where a careful operation distinguishes itself before any solvent is involved.
The solvent-to-material ratio
What it controls
How much solvent is available to dissolve the target compounds. Too little and the extraction is incomplete; too much and the solvent removal becomes the dominant cost.
The practical range
Several volumes of solvent per unit of material, adjusted according to whether one pass or several are planned.
Multiple washes
Fresh solvent on already-extracted material recovers a further fraction. Each wash yields less and carries more of what cold was meant to exclude.
Where operators stop
At the point where the additional yield no longer justifies the solvent removal cost and the quality penalty. It is a commercial judgement rather than a technical limit.
Filtration before evaporation
What is removed
Plant particulates carried over from the extraction vessel. They would otherwise concentrate in the extract during solvent removal.
The methods
Coarse filtration first, then progressively finer stages, sometimes with filter aids. It is standard process engineering.
Why it matters to the result
Particulates in the final extract affect appearance, texture and stability. Removing them is straightforward and it is skipped in careless operations.
What a buyer sees
An extract with visible sediment or cloudiness suggests inadequate filtration. It is one of the few process shortcomings visible without instruments.
Recovering the solvent
Why it is recovered
Ethanol is a substantial ongoing cost at volume. Recovering and reusing it is what makes the economics work.
How it is done
Condensing the vapour from the evaporation stage and returning it to storage, sometimes after further purification.
What accumulates
Trace material carries into the recovered solvent over cycles. Periodic purification or replacement is required.
The traceability implication
Recovered solvent carries material between batches where purification is inadequate. It is a quality question and a traceability one.
The vacuum question
Why reduced pressure is used
It lowers the boiling point of ethanol, so the solvent can be removed at a temperature that destroys less of what is being kept.
How much it helps
Substantially. The difference between evaporating at atmospheric pressure and under good vacuum is the difference between a damaged extract and a preserved one.
The equipment implication
Vacuum capacity is a real capital item and it is where operations differ. Poor vacuum means higher temperatures and a worse result.
What a buyer might notice
A thin aromatic profile on an otherwise well-made extract. It frequently traces back to this stage.
The terpene recovery option
The principle
Volatile compounds evaporate before the solvent does. Collecting them separately at the start of the evaporation preserves them.
What it produces
An aromatic fraction that can be reintroduced to the finished extract afterwards, restoring part of what processing removed.
Whether it counts as addition
Where the compounds came from the same material, it is a restoration. Where they came from elsewhere, it is an addition and belongs on the ingredient list.
What the label should distinguish
The two cases are different and they are frequently described identically. Asking which is a reasonable question.
What ends up in a finished product
The extract itself
A minority of the volume in a finished oil. Most of the bottle is carrier oil.
Residual solvent
At whatever level the removal achieved, measured on the panel and compared against the permitted threshold.
Whatever was added back
Terpenes, from the same material or from elsewhere, where re-aromatisation was performed.
What the ingredient list should show
All of it. The carrier, the extract, and any added aromatic compounds, in descending order of quantity.
Where this route dominates
Bulk supply
Most volume extract on the European market comes through ethanol. The equipment scales readily and the capital requirement per unit of throughput is the lowest of the solvent routes.
Why that matters to a buyer
The extract in an ordinary retail oil most probably came through this route, whatever the product page emphasises. It is the default rather than a distinguishing choice.
What distinguishes operations within it
Temperature, contact time, filtration and vacuum quality. Four variables, none of which appears on any consumer-facing document.
The question that reaches them
The extraction temperature. It is the single most informative thing to ask about this route and a producer answers it directly.
The distillation step afterwards
Why it follows so often
Because a purified fraction is consistent, easy to formulate with, and priced on measured content. Most volume products are built from distillate rather than from crude extract.
What it removes
The aromatic profile entirely, along with the pigments, the waxes and everything else that is not the target compound.
What it produces
A material of high purity and essentially no character. It is a commodity input rather than a finished product.
What follows commercially
Re-aromatisation, frequently, using terpenes from various sources. That is a legitimate practice and it belongs in the ingredient list.
What a full spectrum claim means here
The intended meaning
An extract retaining the range of plant compounds rather than a purified fraction.
What ethanol extraction actually retains
A good deal, before refinement. After winterisation, decolourisation and solvent removal, considerably less.
Where the claim becomes strained
On a product built from distillate with terpenes added back. It contains a range of compounds, and the range was assembled rather than retained.
What settles it
The certificate, showing the minor cannabinoids, and the ingredient list, showing whether anything was added. Both together.
Comparing this route to the alternatives honestly
Its genuine advantages
Scale, cost, and a solvent classified in the least restrictive residual category. All three are real and all three are commercial rather than qualitative.
Its genuine disadvantages
Breadth of extraction, requiring more refinement, and a solvent removal step that costs aromatic compounds.
What cold changes
It addresses the breadth problem directly and substantially. It does not address the solvent removal problem at all.
The honest summary
The volume route, improved considerably by one variable, with a residual solvent panel that is expected rather than optional.
What ethanol is elsewhere
In food processing generally
It is a standard extraction solvent across the food and flavour industries, used for vanilla, for botanical extracts and for a great many flavourings. Its classification in the least restrictive residual category reflects that history.
Why that matters here
The regulatory position on ethanol residues is settled and unremarkable. It is one of the few aspects of this sector where the framework is mature and uncontroversial.
What that does not settle
Whether a particular product’s removal step was thorough. The permitted level is generous and the measured figure still varies between operations.
The row to read
The ethanol figure on the residual solvent panel, against the stated threshold. It is a straightforward comparison and it is one of the clearer readings on any certificate.
The variable worth asking about
Which one it is
The extraction temperature. Everything that distinguishes a good result on this route from a mediocre one traces back to it, and it is an ordinary operational fact rather than a trade secret.
Why the answer is informative
A producer running the process states a figure without hesitation. A reseller passing on a description cannot, because the number was never communicated to them.
A short glossary
Selectivity
The extent to which a process extracts the compounds sought while leaving others behind. Cold is what provides it here.
Winterisation
Chilling an extract dissolved in ethanol so that waxes precipitate, then filtering them out.
Falling-film evaporator
Equipment for removing solvent at scale by flowing the solution as a thin film over a heated surface under reduced pressure.
Decolourisation
Removing pigments from an extract by passing it through adsorbent media. It removes other compounds alongside the colour.
Residual solvent panel
The analytical measurement of solvent traces remaining in a finished product, against established thresholds.
The five checks that apply to any product
The batch certificate
Request it with the number printed on the packaging. A general document for the product line does not cover this batch, and those differences are exactly what it should record.
Total THC
Delta-9-THC plus THCA multiplied by 0.877, because THCA becomes THC under heat and the limit applies to the sum, not to either value alone.
Price per milligram
A division, not an opinion. The only figure that makes two products comparable, whatever the format, process and pack size.
The claims
Without an authorisation number in the EU Register these are assertions, not data — and for cannabidiol that register contains no authorised entry to this day.
The seller’s details
Company name, address and contact. Without them there is also no counterparty to turn to if something turns out to be wrong.
How this connects to the rest
With winterisation
Cold extraction is winterisation done during the process. Understanding one explains the other.
With residual solvents
This is the route where that panel is most clearly expected. Its absence here is a gap.
With carbon dioxide extraction
Ethanol frequently appears in carbon dioxide processes at the winterisation stage, which complicates the solvent-free claim there.
With contaminant testing
The breadth of ethanol as a solvent makes the pesticide panel more consequential on this route.
What this is for in practice
When you see the claim
Cold ethanol is a real technical distinction from warm ethanol. Asking the temperature is a fair question.
When reading a certificate
Expect a residual solvent panel with an ethanol row. Its absence on this route is a substantive gap.
When judging colour
Light suggests cold extraction or refinement. Dark suggests warm extraction with minimal processing.
When comparing extracts
Route, refinement level, panels covered, and per-milligram price. In that order.
Frequently asked questions
What does ethanol dissolve? Nearly everything in the plant: cannabinoids, terpenes, chlorophyll, waxes and water-soluble material.
Why chill it? Because solubility falls with temperature at different rates. Chlorophyll and waxes become far less soluble while the compounds of interest remain available.
How cold? Well below freezing, maintained throughout. Chilling capacity is the principal capital requirement of the technique.
Does contact time matter? Yes. Longer contact extracts more of everything, including what cold was meant to exclude. Brief contact is more selective.
How is the solvent removed? By evaporation under reduced pressure, which lowers the temperature required. The solvent is recovered and reused.
Should there be a residual solvent panel? Yes. It is expected on this route, and ethanol sits in the least restrictive classification with a correspondingly higher permitted level.
Is winterisation still needed? Less so after a cold extraction, because much of the wax stayed in the plant material rather than entering the solvent.
What does a dark green extract indicate? Warm extraction carrying chlorophyll. It requires decolourisation or further refinement to become saleable in most formats.
How does the yield compare? Higher than carbon dioxide, comparable to hydrocarbons, and far higher than mechanical separation.
Why is it the volume route? Straightforward equipment, comparatively low capital cost, and high throughput. Most bulk extract comes through it.
What we check and what we do not
We check what can be checked from documents: official registers, declared contents, certificates of analysis, arithmetic. We test no products, rank nothing, and assert no effects.
This route is instructive because its selectivity comes from one variable. Not from the solvent, which is indiscriminate, but from the temperature at which it is used. Everything that distinguishes a good ethanol extract from a poor one traces back to how cold it was and for how long.
That also makes it the easiest route to ask a useful question about. The temperature is an ordinary operational fact, a producer knows it, and the answer says a great deal about what is in the bottle.