Recycled wool Research
A Comparative Study on the Physical and Performance Properties of Pre-consumer Recycled and Virgin Merino Wools
MSc Textile Science Project
University of Alberta
2024
Recycled wool is widely recognised as a more sustainable alternative to virgin wool. However, whether recycled wool garments remain environmentally beneficial depends not only on the recycled fibre content, but also on how they perform throughout their service life.
This project examined whether pre-consumer recycled wool could perform similarly to virgin Merino wool in apparel applications. The study compared 50% virgin wool / 50% recycled wool blend yarns and fabrics with 100% virgin wool materials through physical testing, performance testing, and tactile sensory evaluation. The project explored not only whether recycled wool can reduce environmental impact, but also whether its durability and handle can support long-term use.
Research Question
Can recycled wool textiles achieve similar performance to virgin wool textiles?
How does recycled wool differ in fibre structure?
How does it perform in knitted fabric?
How do people perceive its handle and comfort?
Why This Matters
Recycled wool can reduce the environmental burden of wool production, but its value depends on whether the final garment can still be worn, accepted, and kept in use. If a recycled wool garment performs poorly or is uncomfortable, its active use length may be shortened, reducing its overall eco-effectiveness.
Most previous studies focused on material properties. This project extends the discussion by connecting textile performance with consumer perception and garment lifespan.
Methodology
Material Preparation
Pre-consumer recycled wool and virgin Merino wool yarns and knitted fabrics were sourced from the same manufacturer. Two fabric/ yarn groups were compared: 100% virgin wool (YV/FV) and 50% virgin / 50% recycled wool blend (YR/FR).
Test yarns
Test fabrics composed from test yarns
Physical & Performance Testing
Standard textile testing methods were used to evaluate the physical and durability-related properties of both yarns and knitted fabrics.
Physical Characterisation | Standard | Objective |
|---|---|---|
Yarn Linear Density | Gravimetric Method | Compare yarn fineness |
Yarn Twist | ASTM D1423 | Measure yarn twist level |
Fabric Mass | ASTM D3776 | Determine fabric weight |
Fabric Thickness | ASTM D1777 | Measure fabric thickness |
Loop Length | Internal Method | Compare knitted loop structure |
Cover Factor | Calculated | Evaluate fabric compactness |
Fibre Diameter | Light Microscopy (40×) | Measure fibre fineness |
Fibre Length | Manual Measurement | Compare fibre length |
Fibre Morphology | Light Microscopy (40×) | Observe fibre surface characteristics |
Performance Testing | Standard | Objective |
|---|---|---|
Yarn Tensile Strength | ASTM D2256 | Evaluate yarn strength and elongation |
Fabric Bursting Strength | ASTM D6797 | Measure knitted fabric strength |
Fabric Pilling Resistance | ASTM D4970 | Assess abrasion resistance and pilling behaviour |
Dimensional Stability | ISO 6330 | Evaluate shrinkage after repeated laundering |
Sensory Evaluation
18 participants
Touch Assessment
Hand & forearm contact
Virgin wool vs Recycled wool blend
Evaluation Setup
Blind Assessment
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Fabric identity concealed
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Random presentation order
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Participants unable to see the samples
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Hand and forearm evaluated separately
Evaluation Attributes
Prickliness
Feeling individual fibre ends against the skin.
Fuzziness
Soft, fluffy and downy surface sensation.
Stiffness
Perceived rigidity and resistance to bending.
Volume / Fullness
Perceived thickness and body of the fabric.
Participants also indicated which fabric they would prefer when considering a garment purchase.
The magnitude scale that was simplified from the original version was presented to the participants.
Assessment Procedure
The fabric specimen was pulled repeatedly on the participants’ volar forearm at approximately 90 degrees. Modified from Santee et al. (2006)
Palm Assessment
Participants freely handled the fabrics using their dominant hand.
Forearm Assessment
Each fabric was repeatedly drawn across the volar forearm using a consistent testing procedure to evaluate tactile comfort under movement.
Why Forearm?
The volar forearm is widely used in textile comfort research because its sensitivity better represents the skin contact experienced during garment wear.
Data Analysis
Experimental data were analysed using descriptive statistics and inferential statistical methods to compare the performance of virgin and recycled wool materials. Statistical analyses were conducted using IBM SPSS Statistics (Version 29), with appropriate tests selected according to the characteristics of each dataset.
Analysis | Purpose |
|---|---|
Descriptive Statistics | Summarise the mean, standard deviation and data distribution |
Independent Samples t-test | Compare differences between virgin and recycled wool groups |
Pearson Correlation | Examine relationships between strength and extension |
Wilcoxon Signed-Rank Test | Compare paired sensory evaluation scores |
Mann–Whitney U Test | Compare sensory responses between palm and forearm assessments |
Key Findings
Fibre Characteristics
Key Takeaway
Recycled wool blend yarn:
Fibre Length: Shorter on average, but not statistically significant
Fibre Diameter: Significantly coarser (p ≤ 0.001)
Fibre Morphology: More damaged and irregular fibre surfaces
The recycled wool blend (YR) exhibited distinct fibre characteristics compared with the virgin wool yarn (YV). While the average fibre length of YR (30.3 ± 16.3 mm) was shorter than YV (41.7 ± 9.2 mm), the difference was not statistically significant (p = 0.07). However, recycled wool fibres showed substantially greater variability, with a higher proportion of short fibres observed.
In contrast, the recycled wool fibres were significantly coarser, with an average diameter of 21.4 ± 4.0 μm, compared with 17.0 ± 3.4 μm for virgin wool (p ≤ 0.001).
Microscopic observation further revealed damaged fibre surfaces and irregular fibre morphology in the recycled wool blend, suggesting that the mechanical recycling process altered the physical characteristics of the fibres.
A microscopic image of a single fibre typical of wool fibres in YV, similar fibres were observed in YR
Selected defective appearances of fibres in YR showing: a) fibre fracture or cracking; b) flattened fibre; c) fibre breakage; d) fibre breakage and irregular fibre diameter; e) impurities spun with recycled fibres; f) impurities attached with recycled fibres; g) ruptured scales; and h) yarn breakage with peeling
The shorter, coarser fibres in YR may be due to mixed sources during collection and to cutting and pulling during mechanical recycling (Baloyi et al., 2023).
These short fibres could not provide sufficient inter-fibre friction due to the short fibre-fibre overlap distance (Mwasiagi et al., 2007); these drawn rovings could be fractured during the spinning steps under the tension and pressure exerted by the rollers (Elhawary, 2015).
Hence, it would be a challenge to spin 100% recycled wool yarn efficiently, and it was suggested that it be blended with other longer fibres.
Yarn Tensile Strength
Key Takeaway
Breaking Force: Comparable between recycled and virgin wool
Elongation: Significantly higher in recycled wool blend
Breaking Time: Significantly longer in recycled wool blend
Interpretation: Higher yarn twist likely compensated for recycled fibre characteristics
The recycled wool blend yarn (YR) demonstrated comparable tensile strength to the virgin wool yarn (YV), despite containing mechanically recycled fibres. The average breaking force was 3.08 N for YR and 3.01 N for YV, with no statistically significant difference observed.
Although the breaking strength was similar, the recycled wool blend exhibited significantly greater elongation before failure and required a longer time to break. These results indicate that the recycled yarn was able to withstand similar loads while deforming further under tension.
The comparable tensile strength may be attributed to the higher yarn twist of the recycled wool blend, which likely compensated for the shorter and more irregular recycled fibres by increasing fibre cohesion within the yarn structure.
Tensile strength of YR and YV yarns showing: a) breaking force; b) maximum load at extension; and c) time to break
Fabric Bursting Strength
Recycled wool blend:
Key Takeaway
Bursting Strength: Significantly lower in recycled wool blend
Time to Failure: Shorter than virgin wool fabric
Extension at Failure: Lower than virgin wool fabric
Interpretation: Reduced resistance to concentrated multidirectional stress
The recycled wool blend fabric (FR) exhibited a significantly lower bursting strength than the virgin wool fabric (FV). On average, FR withstood 185.9 N, compared with 235.6 N for FV, indicating that the recycled wool fabric was more susceptible to rupture under concentrated loading.
In addition to bursting force, the recycled wool fabric reached its maximum load more quickly and exhibited lower extension before failure, suggesting reduced flexibility under multidirectional stress.
Unlike the yarn tensile test, which evaluates a single yarn under uniform tension, the bursting test measures how the knitted fabric behaves under a concentrated force. This better simulates stresses experienced during daily wear, such as pulling garments over the head, stretching sleeves, or movement around elbows and shoulders.
Although the recycled wool blend achieved comparable yarn tensile strength, this performance did not translate directly to fabric durability. The findings suggest that fabric performance depends not only on yarn strength, but also on fibre quality, fibre cohesion, and the way forces are distributed within the knitted structure.
Bursting strength of FR and FV fabrics: a) bursting force; b) time at maximum load; and c) fabric burst extension at maximum load
Tensions applied on the testing materials placed on the testing equipment of a) tensile strength and b) bursting strength tests
Fabric Pilling Performance
Key Takeaway
Pill Formation: Developed progressively with abrasion for both fabrics
Initial Pilling: Appeared later on recycled wool blend
Final Surface Appearance: Fewer attached pills remained on recycled wool blend after 5,000 cycles
Recycled wool did not prevent pilling—it changed how pills behaved.
The recycled wool blend fabric (FR) demonstrated slightly better pilling resistance than the virgin wool fabric (FV). Although both fabrics showed progressive pill formation throughout the 5,000 Martindale abrasion cycles, pill development occurred later on the recycled wool fabric and fewer pills remained attached to the surface at the end of the test.
Both fabrics eventually reached severe pilling after prolonged abrasion. However, the recycled wool blend consistently maintained slightly higher pilling grades during the later stages of testing.
The improved pilling performance was likely not due to fewer pills forming, but to the pills detaching more readily from the fabric surface. The shorter, mechanically damaged recycled fibres were more likely to break during abrasion, allowing pills to wear off rather than remain attached to the fabric.
This finding demonstrates that pilling performance depends not only on pill formation, but also on pill retention.
Average pilling grades of FR and FV in 5000 Martindale cycles
Images of FR (left) and FV (right) after selected cycles
Fabric Dimensional Stability
Key Takeaway
Recycled Wool Blend: Approximately 3% shrinkage after five wash cycles
Virgin Wool: Slight dimensional growth after laundering
Overall Performance: Lower dimensional stability in recycled wool blend
Shrink-resistant finishing may not have been consistently present on the recycled fibres.
The recycled wool blend fabric (FR) exhibited greater dimensional change after repeated laundering than the virgin wool fabric (FV). After five washing cycles, FR shrank by approximately 3% in both the wale and course directions, whereas FV showed a slight dimensional growth rather than shrinkage.
These results indicate that the recycled wool blend was less dimensionally stable during laundering, supporting the hypothesis that recycled wool fabrics are more susceptible to shrinkage.
The greater shrinkage observed in the recycled wool blend may not be solely due to the recycled fibres themselves. A more likely explanation is the absence or inconsistency of shrink-resistant finishing on the recycled fibre component, together with fibre damage introduced during the mechanical recycling process.
These findings highlight that post-processing and finishing treatments remain critical when developing recycled wool textiles, and recycled fibre content alone does not determine dimensional stability.
The average fabric dimensional changes of a) FR and b) FV compared with the original (grey square) after five washing cycles
The average changes in length in wales and courses on FR and FV
Fabric Handle & Tactile Perception
Key Takeaway
Prickliness: Significantly higher in recycled wool blend
Stiffness: Significantly higher in recycled wool blend
Fuzziness: No significant difference
Volume / Fullness: No significant difference
Laboratory performance alone cannot determine the suitability of a textile for apparel. To understand how users experience recycled wool, a blind tactile sensory evaluation was conducted using both palm and forearm assessments.Overall, participants perceived the recycled wool blend (FR) as significantly pricklier and stiffer than the virgin wool fabric (FV). No significant differences were found in the perception of fuzziness or volume/fullness between the two fabrics.
Participants consistently reported stronger tactile sensations when fabrics were assessed using the forearm rather than the palm. Perceptions of prickliness and stiffness increased in the forearm, suggesting that different body areas vary in sensitivity to wool textiles. This highlights the importance of considering garment-body interactions when evaluating textile comfort.
The sensory evaluation suggests that consumer perception is closely related to fibre characteristics. The coarser fibre diameter and mechanically damaged fibre surfaces observed in the recycled wool blend likely increased skin-fabric friction, resulting in a stronger perception of prickliness and stiffness.
These findings demonstrate that improving the tactile comfort of recycled wool depends not only on fibre recycling technologies but also on fibre quality, yarn engineering, and finishing processes.
Overall Preference: 16 of 18 participants preferred virgin wool
Total attribute score, which was grouped in colours by fabric
Overall responses from the participants on each attribute, including responses perceived from the palm and forearm showing: a) prickly, b) fuzzy, c) stiffness, and d) volume/fullness,
The score of each fabric attribute on the palm (left) and forearm (right)
What This Means
Recycled wool is often considered a more sustainable alternative to virgin wool because it reduces the environmental impacts associated with fibre production. However, this research suggests that recycled content alone does not determine sustainability. Instead, the environmental value of a garment depends on how material performance, user experience, and product lifespan work together throughout its use phase.
Eco-effectiveness: Sustainability is More Than Recycled Content
The environmental benefits of recycled wool are typically calculated based on material production, assuming that recycled and virgin wool garments have the same service life. This research suggests that such an assumption may not always reflect real-world use.
Although incorporating recycled wool can reduce greenhouse gas emissions, energy consumption, water stress, and freshwater use during production, these benefits can be diminished if garments fail prematurely because of lower durability, reduced dimensional stability, or poorer user acceptance.
Rather than evaluating sustainability solely by recycled fibre content, eco-effectiveness should also consider whether the finished garment remains wearable and desirable over time.
Active Use Length: Why Garment Lifespan Matters
Environmental benefits decrease if garments are discarded earlier. Based on the scenario adopted in this study, the recycled wool blend garment would need to remain in use for approximately 100 wears to maintain lower environmental impacts than an equivalent virgin wool garment. If the active use length falls substantially below this level, the environmental advantage is progressively reduced.
Factors identified in this study that may shorten garment lifespan include reduced bursting strength, higher laundering shrinkage, and lower tactile comfort. These factors influence not only physical durability but also whether consumers continue wearing the garment.
Environmental impacts per wear of the 100% virgin wool sweater with an active use length of 109 wears, compared to the YR knitted sweater with active use length of 109, 100, 90, 80, and 70 wears for a) GHG emissions; b) Fossil energy consumption; c) Waterstress; d) Freshwater Consumption
Performance Influences Sustainability
The results demonstrate that textile performance should not be evaluated through a single property. While the recycled wool blend achieved yarn tensile strength comparable to virgin wool, differences became evident at the fabric and user levels.
The recycled wool blend exhibited lower bursting strength, greater dimensional change after laundering, and was perceived as pricklier and stiffer by participants. At the same time, it demonstrated slightly better pilling behaviour because pills detached more readily from the fabric surface.
The study also demonstrated that consumers perceived fabrics differently depending on where the textile contacted the body. This suggests that garment comfort cannot be fully assessed by touching fabric with the hand alone.
Together, these findings show that fibre characteristics, yarn construction, fabric performance, and user perception are interconnected. Improving the sustainability of recycled wool, therefore, requires consideration of the entire product system rather than recycled fibre content alone.
Future Directions
Improving Recycled Wool Performance
This research identified several opportunities to further improve the performance and longevity of recycled wool garments.
Future developments may include:
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Better fibre sorting and traceability to reduce variability in recycled fibres.
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Improved shrink-resistant treatments suitable for recycled wool.
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Alternative spinning systems, such as cotton spinning, to better utilise short recycled fibres.
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Knitted structures that improve bursting resistance while maintaining comfort.
Expanding Future Research
This study focused on woollen-spun Merino wool and tactile comfort. Future research could explore:
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100% recycled wool yarns with different spinning methods.
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Blends incorporating recycled synthetic fibres.
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Consumer behaviour beyond tactile perception, including aesthetics, pricing, and garment design.
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The relationship between product design and active use length.
This project fundamentally changed how I think about sustainable textiles. Rather than asking whether recycled wool can replace virgin wool, I became more interested in understanding how textile performance, user behaviour, and product longevity interact to influence environmental impact. This research continues to shape my work in textile science, circular fashion, and material-led design.
If you are interested in this research paper, you are welcome to contact me for further information
Mak, W.S., McQueen, R.H. & Batcheller, J.C. A Comparative Study on the Physical Properties of Pre-Consumer and Virgin Wools, AATCC Textile Discovery Summit, Greenville, SC. 12-14 September, 2023.