Knitted fabric relaxation before cutting means unrolling and flat-laying knitted rolls to release winding and processing tension before spreading, marking, and cutting. Knitted loop structures are elastic, so they distort during roll winding and stenter finishing.
If cutting starts immediately after unrolling, the loops can contract later. Finished panels may shrink, twist, or become dimensionally unstable. Relaxation protocols should normally be set from 24 to 48 hours depending on fiber composition.
Skipping or shortening the relaxation process is a primary cause of quality disputes between apparel brands, garment factories, and textile mills. When a garment fails inspection because the chest width is too narrow or the body length is too short after washing, the fabric’s inherent shrinkage is often blamed first. In many cases, however, the root cause is that the fabric was cut under tension.
The Physics of Roll Winding Tension and Fabric Relaxation
Knitted fabrics consist of interlocking yarn loops that behave like small physical springs. During dyeing, washing, stenter heat-setting, and roll winding, the fabric receives continuous lengthwise tension.
This tension stretches loops into a temporary elongated shape. Once the fabric is tightly wound onto a cardboard roll, roll pressure holds those loops in the stretched state.
When the roll is opened, the pressure releases and the loops begin elastic recovery or viscoelastic creep recovery. In elastane spandex blends, segmented polyurethane chains need time to contract and settle.
If panels are cut before this recovery happens, the fabric can contract after cutting. The result is smaller panels, measurement failure, and twisted side seams before sewing is complete.
Technical Matrix: Relaxation Times by Fiber Composition
To help quality control managers establish correct cutting-room protocols, the table below details the minimum relaxation times, maximum laying heights, and target conditions for various knitted fabric types.
| Knitted Fabric Type | Elastane/Spandex Content | Min. Relaxation Time | Max. Lay Height (Thickness) | Cutting Room Conditions | Primary Control Check |
|---|---|---|---|---|---|
| 100% Cotton / Polyester Jersey | 0% Spandex | 24 Hours | ≤ 10 cm (approx. 20 plies) | 20°C – 24°C, 60% – 65% RH | Stitch count per inch (CPI) stability |
| Nylon / Polyester Spandex Jersey | 8% – 20% Spandex | 48 Hours | ≤ 5 cm (approx. 10 plies) | 20°C – 24°C, 60% – 65% RH | Elastic recovery, width shrinkage |
| Cotton Spandex Rib / Interlock | 3% – 10% Spandex | 48 Hours | ≤ 8 cm (approx. 15 plies) | 20°C – 24°C, 60% – 65% RH | Wale vertical alignment |
| Warp-Knit Tricot / Raschel Mesh | 0% – 15% Spandex | 24 Hours | ≤ 10 cm (approx. 20 plies) | 20°C – 24°C, 60% – 65% RH | Aperture shape & mesh stability |
Dimensional Control Standards: ISO 5077 & ISO 6330 Laundering Tests
Mills and garment makers verify stabilization with standard laboratory testing. The ISO 5077 dimensional change standard measures sample length and width before and after washing.
Use the ISO 6330 domestic washing and drying test standard. It controls variables such as water temperature, detergent type, and drying method.
CottonWorks'shrinkage and skewing reference also frames dimensional change as a response to force, energy and environment. This supports controlling relaxation time, room condition, and tension-free spreading before cut panels are assessed.
- Sportswear tolerance: dimensional change is often controlled within ± 3% or ± 5%.
- Failure signal: fabric cut under tension often exceeds those limits after washing.
- Technical record: confirm pre-shrinkage values on the mill technical data sheet.
At the mill, residual shrinkage is controlled mainly through stenter heat-setting. Positive overfeed lets loops relax and contract under heat, but roll winding still adds tension. Cutting-room relaxation therefore remains mandatory even when the fabric is pre-stabilized.
Skewness and Spirality Controls: ASTM D3882 Bow and Skew Tolerances
Beyond simple shrinkage, tension causes structural distortion in the form of bowing and skewing. Bowing occurs when the knit courses form an arc across the fabric width, while skewing occurs when they lie at a diagonal angle relative to the wales. These distortions are measured using the ASTM D3882 standard test method for bow and skew. For high-quality apparel, the skew tolerance must be kept under 2% to 3%. High skewness causes garment twisting (spirality), where a t-shirt or sweatshirt’s side seams rotate toward the front or back after washing.
To control skewness during spreading, the cutting room must utilize tension-free automatic spreading machines or spread the fabric manually without pulling. The fabric layers must be aligned with the wales running parallel to the table edge. Additionally, the laying height (total thickness of the spread fabric) must be limited. If the fabric pile is too thick, the weight of the top layers compresses the bottom layers, preventing them from contracting. For spandex-rich activewear fabric, the laying height should be limited to 5 cm or 10 plies to ensure uniform relaxation across all layers of the pile.
FAQ: 3 critical cutting-room questions
Q1. How do cutting room temperature and humidity affect the relaxation of nylon spandex fabrics?
Nylon and spandex are highly sensitive to environmental conditions. Nylon is hydrophilic and absorbs moisture from the air, which plasticizes the fibers and allows them to relax. If the cutting room is too dry (relative humidity < 50%), the fibers remain stiff, slowing the relaxation process. The cutting room must maintain a stable temperature of 20°C to 24°C and a relative humidity of 60% to 65% to ensure uniform relaxation within the 48-hour window.
Q2. Is flat-laying always required, or can rolls be relaxed on horizontal pipe racks?
Flat-laying on tables is the most effective method because it eliminates all gravitational pull on the fabric. However, if table space is limited, the rolls can be unrolled and hung over horizontal pipe racks. Ensure the fabric is draped loosely and not pulled tight over the bars, as hanging tension can still introduce lengthwise stretch, particularly in heavy knit structures.
Q3. Can a fabric mill supply “zero-shrinkage” knitted fabric that requires no relaxation before cutting?
No. While mills can pre-shrink and stabilize fabric through sanforizing or stenter overfeeding, the process of rolling the fabric onto cardboard tubes under tension is required for shipping. Without tension, the rolls would be loose, leading to creasing and damage during transit. Therefore, even if the fabric is highly stable, it will always accumulate some winding tension that must be released before cutting.
Q4. What should be fixed before relaxation approval?
Before relaxation approval, the relaxation time, lay height, room condition and post-relaxation measurement rule should be fixed.
For more details on dimensional stability testing, consult the ISO 5077. For details on domestic washing procedures, refer to the ISO 6330, and for bow and skew measurement, review the ASTM D3882 specifications.
Changle Textile manufactures pre-stabilized warp-knitted tricots and high-elastic circular meshes under strict stenter controls to minimize residual shrinkage. Review our high-performance structures in our mesh fabric catalog or contact our engineers to discuss specific fabric applications. For customized development inquiries and tolerance targets, submit the request through the fabric inquiry form.
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