Introduction

CBD hash, derived from low-THC hemp, holds a significant place in the Swiss legal cannabis product market. Thanks to Switzerland’s tolerant regulations for cannabis containing less than 1% THC, more processors and artisans are exploring different production techniques. Among these, manual pressing and hydraulic pressing are notable methods for making hash. Each method relies on well-established principles and involves key technical parameters such as pressure, temperature, and yield. This article provides a detailed overview of these two approaches, drawing on reliable sources — Swiss legislation, reports from accredited laboratories, and peer-reviewed scientific studies — to offer a clear and objective comparison.

Legal Context in Switzerland

Before delving into pressing details, it’s crucial to recall the legal framework for CBD in Switzerland:

• Hemp products whose total THC content stays below 1% fall outside the narcotics regime. That threshold appears neither in the NarcA ¹ nor in the OCStup: it is set out in Annex 1 of the OTStup-DFI ². Note in passing that the reference “OCStup, RS 812.121.11, art. 31”, which one sometimes meets, stacks three errors: the OCStup is RS 812.121.1, and Article 31 was repealed from the NarcA in 2011.

• Companies that legally process hemp are subject to periodic checks to ensure compliance with this threshold. In the case of CBD hash, this monitoring involves analyses in laboratories accredited by the Swiss Accreditation Service (SAS) to confirm that THC content remains below the set threshold.

• The quality and purity of finished products, particularly for solvent residues and contaminants, fall under the enforcement guidance published jointly by Swissmedic, the FOPH, the FSVO and the FOAG ³.

This legislative part forms the essential basis for understanding the context in which CBD hash production takes place and how regulation governs transformation parameters.

General Principles of Hash Pressing

Hash is traditionally formed by agglomerating the trichomes (parts rich in cannabinoids and terpenes) of hemp. When these trichomes are subjected to both pressure and a certain temperature, they clump together and become a compact and malleable mass — called “hash.” Two main categories of pressing processes stand out:

1. Manual Pressing.
   Traditionally used for centuries, it relies on human force (or possibly a rudimentary tool) to compress the plant material. The advantage of this technique is its simplicity.

2. Hydraulic Pressing.
   Based on machines designed to apply multiplied mechanical force, this type of pressing aims for greater precision in terms of pressure and temperature. This can result in better yield and superior consistency of the final product.

In an industrial or semi-industrial production perspective, hydraulic pressing is often preferred for its reproducibility, while manual pressing remains appreciated by enthusiasts seeking artisanal hash.

Manual Pressing: Tradition and Craftsmanship

Historical and Artisanal Techniques

Manual pressing has existed for a long time, particularly in regions where traditional cannabis cultivation is ingrained in the local culture. The oldest traces of hash production by rubbing and pressing date back several centuries, notably in Central Asia and the Middle East. However, these historical data have been mostly reported by travelers’ accounts and anthropological works.

Identified Parameters and Constraints

In the production of CBD hash in Switzerland, manual pressing remains a minority but persists for artisanal reasons. Artisans using this technique generally employ:

• Moderate pressure, achieved through hand action or a rudimentary tool (pestle or roller).

• A slight increase in heat, often produced by the friction of the raw material or simple warming in a water bath. In practice the aim is to stay low, around 40 to 50 °C, softening the resin without driving off the aromatics. That figure comes from custom: terpenes are volatile and heat-sensitive, which is established ⁴, but we know of no published study measuring the effect of a given pressing temperature on the terpene profile of a CBD hash.

• Often lower yield than mechanized pressing, as the force exerted is limited and temperature control is less precise. Yields commonly quoted by producers sit between 5 and 10% (final weight against weight of raw material), depending on flower quality, sieving method and operator dexterity. These figures circulate in the trade without any publication having established them.

Advantages and Disadvantages of Manual Pressing

Advantages:

• Artisanal and authentic aspect.
• Low-cost starting material and simple technique to implement.
• Direct control of texture by the operator.

Disadvantages:

• Limited pressure force, potentially lower yield.
• Difficulty maintaining stable temperature.
• Unpredictable repeatability, complicating product standardization.

Hydraulic Pressing: Precision and Consistency

Operating Principles

Hydraulic pressing relies on a mechanical system (hydraulic press) that applies considerable force via a piston, often adjustable in pressure. In the case of CBD hash, the compression plate’s temperature can also be controlled. What varies concretely is the combination of pressure-temperature-application time.

Pressure and Temperature Data (According to Reports and Studies)

• Pressure:
  The presses used commonly develop 1 to 5 tons of force. Applied over a few square centimetres, that corresponds to a pressure of several hundred to a few thousand psi. These orders of magnitude come from equipment datasheets and workshop practice, not from a study.

• Temperature:
  The ideal temperature for hydraulic pressing can vary between 50 and 70 °C to slightly soften the trichomes without degrading cannabinoids or deteriorating volatile terpenes. This range reflects practice. The underlying principle, the volatility and heat sensitivity of terpenes, is well documented ⁴; the precise 80 °C figure often quoted is not.

• Duration:
  Pressing time generally varies between 30 seconds and 2 minutes. Beyond that, the risk of overheating increases, which can alter the organoleptic profile (taste, smell) of the hash. Additionally, too long a duration can release more lipids and plant compounds that can affect the purity of the final product.

Yield

Thanks to the consistently applied force and perfectly controlled temperature, hydraulic pressing tends to offer better yield. Precise figures largely depend on the quality of the raw material (trichome percentage, hemp variety, moisture). Yields quoted for hydraulic pressing generally sit between 8 and 15%, again from trade custom rather than a published source. Trichome-rich varieties sometimes reach higher rates, while others, less resinous, struggle to exceed 6% yield.

Advantages and Disadvantages of Hydraulic Pressing

Advantages:

• Regularity and reproducibility of the process.
• Better control of temperature, pressure, and contact time.
• Often higher yield than manual pressing.
• Easier to industrialize for larger-scale production.

Disadvantages:

• Significant initial investment to acquire the hydraulic press.
• Specific maintenance required (cylinders, hydraulic fluids, etc.).
• Personnel training needed to optimize parameters and avoid damaging the material.

Key Optimization Factors: Pressure, Temperature, and Yield

1. Pressure

• Why is it important?
  Pressure ensures the agglomeration of trichomes and promotes partial resin extraction. However, excessive pressure can lead to over-extraction, incorporating more undesirable plant materials (chlorophyll, waxes).

• General Recommendations:
  A pressure of about 1 to 3 tons for 10 to 20 grams of trichomes is the setting most often recommended by press manufacturers, beyond which you risk crushing the material rather than agglomerating it. We have set aside here an “internal note” from a university of applied sciences that is sometimes cited: a document the public cannot consult is not a source.

2. Temperature

• Why is it essential?
  Cannabinoids and terpenes are heat-sensitive. Subjecting them to too much heat destroys some of their volatile compounds, while too low a temperature limits resin fusion and complicates hash cohesion.

• Optimal Temperature Zones:

  • Between 40 and 50 °C for slower manual pressing.
  • Between 50 and 70 °C for controlled hydraulic pressing.
  • Beyond 80 °C: increased risk of terpene degradation, according to trade practice rather than a published measurement.

3. Yield

• Definition:
  Yield is the ratio between the amount of hash obtained and the amount of raw material used. It closely depends on the selected hemp variety (resin-rich or not), sieving fineness, mastery of pressing parameters, and product freshness.

• Manual vs Hydraulic Comparison:

  • Manual pressing: 5 to 10% according to trade custom.
  • Hydraulic pressing: 8 to 15%, sometimes more (same source).

In summary, pressure and temperature strongly influence operation efficiency. By mastering these two parameters, producers manage to optimize yield without sacrificing overall hash quality.

Preservation and Stability of Hash

Storage conditions have a notable impact on the long-term quality of hash, whether produced manually or hydraulically:

• Relative Humidity:
  Excessive humidity can promote mold growth, while too dry an atmosphere could accelerate cannabinoid oxidation. According to the FOPH, for finished CBD cannabis products, a relative humidity between 55 and 62% is often considered satisfactory.
  This 55 to 62% window is the range retained by the trade. It is a window, not a minimum: below it the resin dries out and terpenes evaporate, above it the risk of mould rises.

• Storage Temperature:
  It is recommended to store hash in a cool place, between 15 and 21 °C, away from light. Higher temperatures accelerate terpene degradation and can alter product consistency.

• Containers:
  Airtight, opaque, or amber glass packaging helps protect hash from UV rays and external contamination. SAS-accredited laboratories often recommend storing reference samples in vacuum-sealed containers to maintain their integrity over the long term.

Consumption Modes and Usage Precautions

Whether hash is obtained by manual or hydraulic pressing, users generally prefer two consumption modes:

1. Low-Temperature Vaporization:
   Vaporisation is generally practised between 160 and 180 °C, below the point of combustion. The reference study on a hot-air vaporiser worked at 200 °C and showed reproducible cannabinoid delivery, comparable in efficiency to smoking but without the combustion products ⁵.

2. Infusion / Cooking:
   Some consumers incorporate hash into infusions or recipes. Since cannabinoids are liposoluble, they infuse more effectively in a fatty base (butter, oil) at a moderate temperature (around 100 °C).

Moreover, even if the THC level is below 1%, it is advisable to respect dosages and check one’s tolerance level. CBD is not psychotropic in the sense THC is, but neither is it inert: the WHO notes reported effects such as somnolence, and marked individual variability ⁶.

Health Aspects and Controls

Transforming hemp into hash involves adhering to strict sanitary standards:

• Contaminant Analyses:
  SAS-accredited laboratories regularly conduct tests to ensure the absence of pesticide residues, heavy metals, or molds in the final product.
  The relevant accreditation is to ISO/IEC 17025, issued by the Swiss Accreditation Service, whose register is public ⁷. There is no separate “cannabis” accreditation.

• Traceability:
  Swiss legislation requires precise documentation of flower origin (variety, production batch, THC and CBD levels) as well as hash manufacturing methods. This traceability facilitates controls and can guarantee consumer safety.

• Hygiene and Good Manufacturing Practices (GMP):
  Production facilities must comply with hygiene guidelines to avoid product contamination. These standards are often inspired by pharmaceutical recommendations for handling any medicinal plant-based product.

Economic Elements and Sustainability

Economies of Scale

• Initial Costs:
  Manual pressing requires little material investment, while hydraulic pressing involves a significant budget for acquiring professional equipment. However, at medium and large scales, hydraulic automation generates more stable and often superior yield, making the operation more profitable in the long term.

• Labor:
  Manual pressing is very labor-intensive. Therefore, for large volumes, labor costs become high, and overall productivity remains limited. In contrast, hydraulic pressing can be operated by fewer people while maintaining higher production.

Environmental Impact

From an ecological standpoint, each method has its advantages and disadvantages:

• Manual Pressing:
  Consumes little energy but can be less efficient and sometimes requires artisanal heating of plant material (fire, water bath), involving less controlled combustion or heat source.

• Hydraulic Pressing:
  Requires electricity to power the press and control temperature. However, energy is better targeted and can come from renewable sources if the operator is equipped accordingly. Higher yields also reduce the amount of plant waste relative to the amount of hash produced.

Advice for Choosing the Right Method

For artisans wishing to start CBD hash production in Switzerland, the choice between manual and hydraulic pressing depends on:

1. The amount of raw material to process.
   On a small scale (less than a few kilograms of flowers per month), manual pressing may suffice. However, beyond that, investing in a hydraulic press is often justified.

2. The level of control sought.
   If standardization and reproducibility are priorities, the hydraulic machine is preferable. For an artisan focusing on authenticity and flexibility, manual pressing is acceptable.

3. The available budget.
   Specialized hydraulic presses for cannabis can represent a significant cost (several thousand Swiss francs), which may not be accessible to all structures.

4. Market demand.
   Some consumers value the “handmade” aspect. Others prefer a product with homogeneous and stable characteristics, a sign of seriousness for medicinal or wellness use.

Conclusion

The choice between hydraulic and manual pressing for CBD hash production in Switzerland is closely linked to considerations of quality, yield, and legal compliance. Manual pressing, rooted in tradition, appeals with its artisanal side but remains limited in terms of pressure exerted and temperature precision. Hydraulic pressing, on the other hand, allows for increased standardization, greater reproducibility, and generally higher yield, although it requires a higher initial investment and technical expertise.

In the Swiss environment, where the legal framework tolerates up to 1% THC in cannabis-based products, quality and traceability are imperatives. SAS-accredited laboratories play a fundamental role in controlling hash purity, verifying cannabinoid levels, and ensuring the absence of contaminants. Pressure, temperature, and pressing time parameters are the subject of ongoing research, both by industries seeking to optimize efficiency and scientists evaluating the integrity of active compounds.

Ultimately, the decision to use manual or hydraulic pressing depends not only on the technique itself but also on production strategy, brand philosophy, market demand, and financial resources. As demonstrated by various studies published in specialized journals, the key lies in adhering to good manufacturing practices, respecting the Swiss legal framework, and committing to providing a high-quality product to consumers, whether it is artisanal hash or from a sophisticated industrial process.

With growing demand for CBD-derived products, innovation continues. New electric presses with digital control are emerging, as well as prototypes combining automated sieving extraction and sequential pressing. Undoubtedly, this technological evolution will continue to improve the quality, consistency, and safety of CBD hash in the Swiss market, always respecting current standards and traditional know-how.

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Sources

Footnotes

1. Swiss Confederation. Federal Act on Narcotics and Psychotropic Substances (NarcA), RS 812.121. https://www.fedlex.admin.ch/eli/cc/1952/241_241_245/en ↩

2. Swiss Confederation. FDHA Ordinance on the Lists of Narcotics, Psychotropic Substances, Precursors and Chemical Adjuvants (OTStup-DFI), RS 812.121.11, Annex 1. https://www.fedlex.admin.ch/eli/cc/2011/363/fr ↩

3. Swissmedic, FOPH, FSVO, FOAG. “Products containing cannabidiol (CBD): overview and enforcement aid”. https://www.swissmedic.ch/dam/swissmedic/fr/dokumente/marktueberwachung/abrenzungsfragen/produkte_mit_cannabidiolcbdueberblickundvollzugshilfe.pdf.download.pdf/produits_contenantducannabidiolcbdvuedensembleetaidealexecution.pdf ↩

4. Brenneisen R. “Chemistry and Analysis of Phytocannabinoids and Other Cannabis Constituents”, in ElSohly M. A. (ed.), Marijuana and the Cannabinoids, Humana Press, 2007, ch. 2, pp. 17–49. https://doi.org/10.1007/978-1-59259-947-9_2 ↩ ↩²

5. Hazekamp A., Ruhaak R., Zuurman L., van Gerven J., Verpoorte R. “Evaluation of a vaporizing device (Volcano) for the pulmonary administration of tetrahydrocannabinol”, Journal of Pharmaceutical Sciences, 2006, vol. 95, no. 6, pp. 1308–1317. https://doi.org/10.1002/jps.20574 ↩

6. World Health Organization. “Cannabidiol (CBD): Critical Review Report”, Expert Committee on Drug Dependence, 2018. https://cdn.who.int/media/docs/default-source/controlled-substances/whocbdreportmay2018-2.pdf ↩

7. Swiss Accreditation Service (SAS), register of laboratories accredited to ISO/IEC 17025. https://www.sas.admin.ch/sas/en/home.html ↩