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Proper use of Vacuum Ovens

cannabis leaves and a vacuum oven in a orange banner


Dr. George Stantchev
Dr. George Stantchev

PHD, MBA, MSEE, Entrepreneur and CEO of most innovative extraction technology company.

Vacuum purging plays a crucial role in refining cannabis concentrates. It ensures they are free from residual solvents and moisture while achieving the desired consistency and texture. The vacuum oven is also an excellent tool for decarboxylating your flower while preserving the terpenes. 

Vacuum Ovens in Cannabis Extraction

Many cannabis enthusiasts are unaware that the products they love, such as waxes, shatters, and resins, owe their quality to the use of vacuum ovens in extraction laboratories like those from PURE5™. These ovens are indispensable tools for extractors, facilitating the creation of safe and flavorful cannabis concentrates.

In the liquified gas extraction process, whether using aerosol, butane, propane, or other methods, the result is potent but still saturated by gas oil. Regardless of the extraction technique, this oil may contain moisture and residual solvents.

vaccum oven purging BHO extractVacuum ovens employ a vacuum-assisted purging process to effectively eliminate impurities from the thick cannabis concentrate oil through evaporation, leaving behind a cleaner concentrate suitable for further processing. This process, crucial in purging hash oil, ensures the final product is free from solvents while preserving its rich terpene and cannabinoid profile.

The Process of Purging

The principle of purging involves raising the temperature to maintain low extract viscosity and lowering pressure to drive the undesirable gaseous compounds, particularly solvents, out of cannabis concentrate.

Reducing the pressure decreases the boiling point of water and residual solvents trapped and creates an easy way for those gasses to escape. This combination of temperature and pressure enables the removal of unwanted compounds without overheating and decarboxylating the cannabinoids.

The impact of atmospheric pressure on boiling points is critical. Lowering the pressure within the vacuum chamber reduces the temperature needed for off-gas solvents, thereby preserving sensitive cannabinoids and terpenes that would otherwise be lost at higher temperatures.

Parameters and Duration

orange cannabis shatter made with vacuum ovenThe specific parameters, temperature, pressure, and time vary depending on the boiling point of the gas that needs to be purged. For butane with a boiling point of 1C or 34F, temperatures are maintained around 100 ºF, aiming for a pressure setting close to ​​-29.92 inHG (inches of mercury) and can take up to a few days.

For aerosols with a boiling point of -27C or -15F, the temperature is 38C, close to 100F, and the process is much faster in one or two hours due to the smaller and lighter molecule that finds its way out faster.

In general, the purging process can last anywhere from a few hours to several days, with operators relying on visual clues or analytical testing to determine when impurities have sufficiently evaporated.

In producing shatter, the crude oil is spread thinly over silicone mats within the vacuum oven. Thinner layers enhance the efficiency of purging, preserving volatile terpenes. However, thicker films may be used for specific product textures.

cannabis extract in an vacuum oven with a lot of bubbles in itOperators periodically flip the extract sheets during the purge to enhance efficiency. Bubbles appearing on the surface indicate the evaporation of solvents.

The purge concludes when no further bubbles form and the texture stabilizes. Despite visual indications, analytical testing is crucial to ensure residual solvent levels meet consumer-use safety standards.

Vacuum Ovens for oil decarboxylation

Cannabis extracts often contain cannabinoids in their acidic forms, such as THCA and CBDA, which are not psychoactive. Decarboxylation is removing a carboxyl group from cannabinoids through heating, converting them into their active forms (THC and CBD). Vacuum ovens provide a controlled environment for this process, preventing the degradation of cannabinoids and terpenes due to oxidation.

You can test your decarbed oil for performance as follows: It is known that the decarb factor is .877 X THCA value by weight.  You can weigh the oil before decarb and then post-decarb. You will take the starting weight x .877, which should be close to your ending weight after decarb.

Vacuum Ovens for flower decarboxylation

Vacuum ovens help maintain consistent temperature and pressure throughout extraction, ensuring that cannabinoids and terpenes are preserved and the final product is high quality. They also help remove moisture, which can lead to microbial growth and degradation of the extract.

It is best to use a Vacuum Oven to avoid the smell and preserve the terpenes in flowers. For Cannabis, preheat the oven to the desired temperature (240 F/115C). Place the material in and set up the timer for 1 hour. For hemp, preheat the oven to the desired temperature (275 F/135C). Place the bags in and set up the timer for 1 hour. Vacuum the chamber and turn off the valve to hold a steady vacuum. By the end of the hour, the vacuum will be settled to zero, which indicates that your material has been decarboxylated. 


Vacuum ovens are indispensable tools in cannabis extraction. Compared to other methods, they can significantly reduce the time required for purging solvents and decarboxylating extracts. This efficiency is crucial for large-scale cannabis extraction operations. Vacuum ovens effectively purge impurities while preserving the integrity of cannabinoids and terpenes, ensuring the production of clean, high-quality concentrates.

PURE5™ high-temperature vacuum ovens are the pinnacle of efficiency and precision in this field. Engineered with the extractor’s needs in mind, these ovens offer exceptional performance across different scales of operation, providing extractors with the means to achieve superior results in concentrate production.

PURE5's vacuum oven with drawer for cannabis post processing banner with the units and cannabis leaves on the background

Advantages of PURE5™ Vacuum Ovens

  • Efficiency: Both the 50L and 500L models are designed for maximum efficiency, significantly reducing purging time and energy consumption.
  • Precision: Accurate temperature control and vacuum settings ensure consistent results batch after batch.
  • Quality: PURE5™ vacuum ovens guarantee compliance with safety and quality standards, producing concentrates free from residual solvents.

The 50L Vacuum Oven by PURE5™ is tailored for small to medium-scale operations. Despite its compact size, this oven boasts precise temperature control and efficient vacuum purging capabilities, ensuring the preservation of concentrate quality. It is an ideal choice for extractors looking to maintain the integrity of terpene and cannabinoid profiles.

The PURE5™ 500L Vacuum Oven is a good choice for larger-scale extraction facilities. With a substantial capacity and powerful heating element, this model enables batch processing of larger quantities of concentrate. Equipped with multiple shelves and a vacuum pump, the 500L oven ensures rapid and thorough purging, meeting the demands of high-volume operations.

Whether for boutique operations or large-scale facilities, PURE5™ vacuum ovens are indispensable tools for extractors seeking to elevate the quality and safety of their cannabis concentrates. These ovens offer a range of tailored solutions, combining efficiency, precision, and quality assurance to meet diverse extraction needs effectively.

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