Hemp fibre processing is the bottleneck of the entire hemp fibre industry. Without adequate processing capacity, raw hemp stalks cannot become saleable bast fibre or hurd. Three steps stand between a harvested stalk and saleable fibre, and each one shapes the economics of everything downstream.
The processing chain
Hemp fibre processing transforms harvested hemp stalks into separated bast fibre (for textiles, rope, paper) and hurd (for hempcrete, animal bedding, biocomposites). The process broadly involves:
- Cultivation of fibre-specific hemp varieties
- Harvesting at peak fibre maturity
- Retting, controlled biological breakdown of stem material
- Drying the retted stems
- Decortication, mechanical separation of bast from hurd
- Refinement, further processing for specific end markets
Retting: the bottleneck step
Retting is the controlled microbial decomposition of the pectins that bind the bast fibre to the hurd. Without proper retting, mechanical separation is essentially impossible. Several methods exist:
Dew retting
The hemp stalks are cut and left in the field for several weeks. Natural microbes from the soil and rain break down the pectins gradually. This is the simplest, lowest-cost method but produces variable results based on weather and is unpredictable in timing.
- Time: 2-6 weeks
- Quality: Variable
- Cost: Low
- Weather dependence: High
- Suitable for: Lower-value fibre markets, animal bedding, hempcrete hurd
Water retting (tank or pond retting)
Stalks are submerged in water tanks or ponds for controlled microbial decomposition. Produces higher quality fibre than dew retting but generates wastewater requiring treatment. Less common today due to environmental concerns about effluent.
- Time: 10-14 days
- Quality: High
- Cost: Higher than dew (water/effluent costs)
- Suitable for: Premium textile fibre
Enzymatic retting
Industrial process using purified enzymes to break down pectins. Produces consistent, high-quality fibre but requires significant infrastructure investment. Used at some industrial-scale processing facilities in Europe.
- Time: Hours to days
- Quality: Very high, consistent
- Cost: High (enzyme costs, equipment)
- Suitable for: Industrial textile applications
Chemical retting
Uses alkaline chemicals to dissolve pectins. Fast but harsh on the fibre and produces chemical effluent. Rarely used today due to environmental and product-quality concerns.
Decortication: the mechanical separation
After retting, the stalks pass through decorticator machines that mechanically separate the bast fibre from the hurd. Modern decorticators use:
- Crushing rollers to break the hurd into smaller pieces
- Beating drums to dislodge bast fibre from the hurd
- Air separation to remove fines and dust
- Sieving to grade the output into different fibre lengths and hurd sizes
Decorticator throughput varies dramatically by machine size:
- Small farm-scale decorticators: 100-500 kg/hour
- Mid-scale industrial: 1-3 tonnes/hour
- Large industrial: 5-15 tonnes/hour
Refinement and grading
After decortication, the bast fibre is further refined for specific end markets:
For textiles
- Hackling (combing) to align fibres
- Cottonization or steam treatment to soften the fibre
- Carding to prepare for spinning
- Spinning into yarn
For rope and cordage
- Cleaning and grading by length
- Twisting into ropes of various sizes
For paper
- Pulping (chemical or mechanical)
- Bleaching (optional)
- Sheet formation
For composites
- Cutting to specific length
- Optional surface treatment to improve resin compatibility
- Drying to controlled moisture content
Hurd processing
The hurd (woody core) requires different processing for its various end markets:
- For hempcrete: sizing into specific particle ranges (typically 5-25mm), dust removal
- For animal bedding: drying, sometimes treating for absorbency
- For mulch: minimal processing beyond size grading
- For biocomposites: milling to specific particle size, drying
Why Canada lags in fibre processing
Canada has significant hemp grain processing capacity but limited fibre processing infrastructure. Several factors:
- Capital cost. Industrial decorticators cost $5-25 million; complete fibre processing facilities $25-100+ million
- Throughput requirements. Decortication is only economic at scale, requiring consistent fibre supply
- Market development. End markets for Canadian-processed fibre are still developing
- Risk profile. Investors hesitant about hemp fibre infrastructure given historical industry volatility
- Geographic dispersion. Fibre supply transportation costs are significant due to bulky low-value raw material
Investment trajectory
Several Canadian projects are addressing the processing gap:
- Prairie-based decortication facilities (Manitoba, Saskatchewan)
- British Columbia hemp processing initiatives
- Eastern Canadian niche processors serving regional markets
The trajectory is positive but slower than the demand growth, meaning Canadian hemp fibre continues to be partially exported as raw material for processing elsewhere.