分类： Application guides

There is no universal sample count for checking fabric stretch ratio. The selected test method determines the required laboratory specimens, while the buyer's sampling plan must separately cover the rolls, dye lots, fabric directions, and locations needed to represent the sourcing decision.

Define what “stretch ratio” means before sampling

Suppliers and buyers may use “stretch ratio,” “elongation,” and “stretch percentage” differently. The test request should define the calculation and reporting unit instead of relying on the phrase alone.

For percentage stretch:

Stretch (%) = (extended length − initial length) ÷ initial length × 100

Illustrative calculation — not a ClothFactory test result: a marked length that increases from 100 mm to 150 mm has:

(150 mm − 100 mm) ÷ 100 mm × 100 = 50% stretch

The same result could be described as an extended-length ratio of 1.5:1, so the report must state which convention it uses. It should also distinguish maximum extension from force at a specified extension, recovery after release, and residual growth. These values answer different procurement questions.

Separate laboratory specimens from production coverage

Stretch testing involves several sampling levels:

• Production lot: the quantity covered by one acceptance decision.
• Rolls or production groups: represent dye lots, knitting positions, finishing groups, dates, or other traceable sources.
• Locations within a roll: reveal variation along the roll length or across its usable width.
• Fabric directions: normally require separate evaluation because coursewise and lengthwise behavior can differ.
• Test specimens: pieces prepared and measured according to the selected method.

Several specimens cut beside each other improve repeatability for that sampled location, but they do not demonstrate consistency across multiple rolls. Ten specimens from one roll still represent one roll.

Let the test method set the specimen count

Stretch methods differ in specimen dimensions, gauge length, load or force, extension rate, cycling, hold time, recovery time, and calculation. Select the method first, then complete its required specimen set for every sampling group in the buyer's plan.

The report should state:

• method identifier and edition;
• specimen count and direction;
• conditioning and relaxation procedure;
• gauge length and specimen dimensions;
• applied load or target extension;
• extension rate, hold time, and number of cycles;
• recovery interval and residual-growth calculation;
• pre-wash or post-wash condition;
• individual results, average, range, and specimen origin.

Do not divide one method-required specimen set among unrelated rolls unless the method and purchase agreement explicitly permit that design.

Adjust production coverage to the sourcing stage

The plan should state how to handle an outlying roll or group. Options may include adjacent resampling, expanded roll coverage, investigation, segregation, reprocessing, or rejection. A passing overall average should not automatically release a roll with unacceptable recovery or force behavior.

Use an illustrative sampling calculation correctly

The following is a hypothetical buyer-defined plan, not an industry standard or ClothFactory test result. Suppose a buyer selects four representative rolls and samples two locations per roll:

4 rolls × 2 locations = 8 sampling groups

If both principal directions are evaluated separately:

8 sampling groups × 2 directions = 16 direction-specific groups

Each group must then supply the complete number of specimens required by the selected method. If that number is n, the total is:

16 direction-specific groups × n method-required specimens

The correct number of rolls depends on lot size, dye-lot structure, color and finish groups, earlier quality history, construction risk, and the purchase agreement. The example shows the calculation logic, not a default requirement.

Measure more than maximum stretch

Maximum elongation alone does not show whether a fabric will provide support or maintain fit. For leggings, sports bras, underwear, or shapewear, buyers may also need:

• force at the extension expected in the garment;
• recovery after a defined hold and relaxation period;
• residual growth after repeated cycling;
• results after the intended wash and drying procedure;
• appearance, cover, or print integrity under an agreed extension.

Spandex percentage is not a substitute for these measurements. Yarn size, knit geometry, spandex feeding, heat setting, finishing, and specimen direction all influence the result.

Keep every comparison condition consistent

Stretch results are comparable only when the conditions match. Use the same specimen direction, dimensions, conditioning, gauge length, load or extension, rate, cycles, hold time, recovery interval, and laundering condition across candidates.

Record the exact fabric code, color, finish, roll, dye lot, and sampling location. Test the finished construction rather than relying only on greige fabric or an unfinished development swatch. Dark colors, special finishes, or different heat-setting conditions may need separate confirmation when they create a different production risk.

Interpret variation before averaging

Review individual and group results, not only the mean. A wide range can indicate variation by roll, direction, location, finish, or test preparation. Investigate that source before adding more results to an average.

Retesting adjacent material can help determine whether an unusual result is local or representative, but the original result should remain in the record. The purchase agreement should define whether acceptance applies to each roll, each production group, or the lot as a whole.

Information buyers should include in the request

Provide the supplier or laboratory with:

• fabric code, composition, knit construction, finished GSM, and usable width;
• intended garment, body zone, fit, and expected extension;
• selected test method and reporting convention;
• specimen directions and production sampling locations;
• conditioning, cycling, hold, recovery, and wash requirements;
• required force, stretch, recovery, or growth limits;
• lot definition and roll-selection rule;
• report format showing individual results and full traceability.

Procurement next step

Choose the stretch method and reporting convention first. Then build a separate production sampling plan that covers the rolls, dye lots, directions, and locations relevant to the order. ClothFactory can prepare identified nylon-spandex or polyester-spandex specimens, but the buyer and supplier should agree the method, sampling coverage, garment extension, recovery interval, and acceptance limits before using the results for bulk approval.

Free-cut fabric can be used without a sewn hem only when the raw edge remains stable, comfortable, and durable in the finished garment. Buyers should approve the actual fabric construction, cut method, edge treatment, garment zone, and wash cycle together; a nylon-spandex or polyester-spandex label alone is not enough.

Treat free-cut as a construction decision

In this context, free-cut means a panel is cut to its final outline without a traditional folded hem. The edge may remain raw, or it may be stabilized by laser cutting, heat sealing, ultrasonic bonding, binding, or another process. These methods are not interchangeable. A raw knitted edge and a bonded edge have different failure risks and must be specified separately.

The correct question is not whether a fabric is “free-cut.” It is whether the chosen edge can maintain its shape and appearance at the garment’s actual extension, abrasion points, and care conditions.

Check the fabric before choosing the edge treatment

Composition and knit construction

Nylon-spandex and polyester-spandex knits are common candidates for activewear, but composition does not determine edge performance. Record the knit type, yarn information available from the supplier, finished GSM, usable width, stretch direction, and any finishing treatment. Compare samples from the same construction and finish when evaluating edge behavior.

Curl, fray, and recovery

Inspect cut strips in both principal directions. Record whether the edge rolls, curls, ladders, frays, or develops a hard line after cutting. Then extend the strip to the level expected at the waistband, leg opening, bra armhole, or shapewear opening and check whether the edge returns without permanent distortion.

GSM and edge stability

GSM can help compare mass and cover, but it is not an acceptance rule. A heavier fabric may still curl if the knit structure is unstable, while a lighter fabric may perform well when the edge is bonded or placed in a low-stress zone. Confirm edge behavior on the finished fabric rather than approving by weight alone.

Match the edge method to the garment zone

This table is a screening framework, not a blanket approval. A design that works on a sports-bra armhole may fail at a leg opening because the extension, friction, and seam forces are different.

Separate raw edges from bonded or enclosed edges

Heat sealing and ultrasonic bonding can stabilize an edge without a folded hem, but they introduce their own development variables: equipment settings, adhesive or film compatibility where applicable, line strength, hand feel, and wash durability. Overlock and flatlock stitching secure an edge through sewing and should not be described as an unprocessed free-cut edge.

Ask the garment factory to identify the edge process on the tech pack. The fabric supplier should then evaluate the matched fabric and process combination, not an isolated swatch cut with an unrelated tool.

Use a defined edge-approval test

1. Cut specimens in the main and crosswise directions using the intended production method.
2. Record the initial edge length, width, GSM, and visual condition after relaxation.
3. Extend the edge to the garment’s intended strain and record curl, fray, laddering, and residual growth.
4. Launder the specimens using the planned care cycle, then repeat the relaxed and extended inspection.
5. Expose the edge to the relevant abrasion or repeated-extension condition.
6. Make a garment or seam mock-up and inspect comfort, appearance, and edge stability at the actual placement.
7. Approve a sealed reference sample with the cut method, edge treatment, tolerances, and wash condition recorded.

Illustrative calculation — not a ClothFactory test result: if a 100 mm raw edge is extended by 30%, its temporary length is:

100 mm × (1 + 0.30) = 130 mm

After release, measure the remaining length and edge shape. This calculation defines the extension condition; it does not establish a universal pass limit. The buyer and supplier must agree the acceptable residual growth and appearance for the garment zone.

When hemming or reinforcement is usually safer

Use a hem, binding, enclosed seam, or another edge reinforcement when:

• the knit is open, lightweight, or visibly prone to laddering or fraying;
• the edge carries high tension, repeated abrasion, or concentrated seam load;
• the edge will contact skin and a raw or bonded line feels harsh;
• the design requires a precise visible edge or stable opening dimension;
• the cut process or bonding method is not controlled in bulk production;
• wash or wear testing shows permanent curl, growth, delamination, or distortion.

Information to include in a sample request

Send the supplier and garment factory the same brief:

• garment type and exact edge location;
• fabric composition, knit construction, finished GSM, and usable width;
• stretch direction and expected extension at the edge;
• intended cut tool or edge process;
• wash method, number of cycles, and any abrasion or wear condition;
• required appearance, comfort, recovery, and dimensional tolerances;
• reference sample or pattern section showing the edge geometry.

Do not approve a free-cut construction from a relaxed fabric swatch alone. A successful sample must represent the production fabric, cut method, edge process, garment pattern, and care cycle.

Procurement next step

For a free-cut activewear request, send a pattern section or edge sketch together with the target composition, GSM, extension, finish, cut process, and care requirements. Ask for cut-edge specimens and a small garment or seam mock-up before bulk approval. ClothFactory can compare a suitable nylon-spandex or polyester-spandex construction, but the final decision should remain tied to the tested edge process and garment placement.

When reviewing gym shorts fabric samples, buyers should approve the finished construction against the garment brief—not just the fiber blend or hand feel. The critical checks are stretch and recovery, coverage and weight, moisture and air behavior, surface durability, colorfastness, and consistency after the agreed care cycle.

Define the gym-shorts brief before judging the swatch

Gym shorts may use a loose outer shell, a close-fitting liner, or both. A shell intended for high-sweat training has different priorities from a liner that must stay opaque and recover after repeated extension. Before comparing samples, record the garment layer, body coverage, target fit, climate, color range, wash method, and whether the fabric will be used next to skin.

For example, a buyer developing a close-fitting training short should review the fabric at the extension expected around the seat and thigh, not only in its relaxed state. A looser shell may place more weight on drape, air exchange, and abrasion at the hem. These are application decisions; no single GSM or composition is correct for every gym-short design.

Check composition and construction together

Nylon-spandex and polyester-spandex knitted fabrics are both reasonable starting points. Nylon-spandex may be shortlisted when a smooth hand and close-to-skin comfort are important. Polyester-spandex may be considered for constructions targeting quick drying or repeated-use durability. Neither conclusion is automatic: yarn, knit geometry, finishing, color, and garment design can change the result.

Ask the supplier to state the fiber composition, knit construction, finished GSM, usable width, and any finishing treatment on the sample sheet. Do not treat a reference color card or a blend name as proof of a finished performance property.

Evaluate stretch and recovery under defined conditions

Hand-stretching a swatch is useful for screening, but it cannot replace a comparable measurement. Request stretch and recovery in the main and crosswise directions, with the extension level, hold time, recovery time, conditioning, and wash history recorded. A fabric can feel flexible while still showing unwanted growth after wear.

Review the sample both relaxed and extended. Look for loss of cover, distorted courses, shine, or a recovery delay that could affect the waistband, leg opening, or liner fit. Approve the final construction only after a garment sample confirms that the fabric response matches the pattern and seam design.

Use GSM to compare weight and consumption, not to promise comfort

GSM helps estimate garment mass, marker consumption, and the amount of material used in each size. It does not independently establish breathability, opacity, or durability. Thickness, cover, yarn size, loop structure, and finishing must be reviewed with it.

Illustrative calculation — not a ClothFactory test result: assume a finished gym short uses 0.9 m² of one fabric before cutting waste. At 180 gsm, the fabric contribution is:

0.9 m² × 180 g/m² = 162 g

At 220 gsm, the same area contributes approximately 198 g, a difference of 36 g before seams, trims, waste, and any lining. Use this calculation to compare weight and costing. Confirm comfort and coverage with the finished garment rather than inferring them from GSM alone.

Check moisture behavior, surface durability, and color

If the product brief includes moisture-management language, request a defined test on the finished fabric. A topical treatment or a supplier description is not enough to support a garment claim. Record the test method, conditioning, and pass requirement so results from different samples remain comparable.

For repeated gym use, review pilling, abrasion, snagging, dimensional stability, and seam-area distortion. Inspect the fabric after the agreed wash procedure and compare the surface before and after laundering. Confirm colorfastness for the actual shade range; one approved color does not automatically represent every dark, bright, or neon color.

Request evidence that can be compared

Send identical requirements to each candidate supplier. Comparing one supplier’s finished GSM with another supplier’s greige GSM, or comparing recovery values from different test conditions, produces misleading conclusions.

Use a controlled sample-approval workflow

1. Confirm the garment brief, pattern intent, color standard, and care label.
2. Record each sample’s composition, construction, GSM, width, finish, and supplier reference.
3. Screen hand, drape, stretch, recovery, and coverage in relaxed and extended states.
4. Run the agreed laboratory and wash checks on matched specimens.
5. Make a garment sample and inspect waistband, leg opening, seams, opacity, and post-wash shape.
6. Approve a sealed reference swatch and written tolerances before bulk production.

Avoid common sample-review mistakes

• Approving by touch alone. A soft hand does not confirm recovery, coverage, or durability.
• Treating fiber content as a complete specification. The same blend can behave differently at different GSMs, constructions, and finishes.
• Using GSM as a comfort guarantee. Added mass may increase weight without improving airflow or wear comfort.
• Testing only a relaxed swatch. Gym shorts experience extension at the waistband, seat, and leg opening.
• Assuming one color represents the range. Dye depth and finishing can affect hand, stretch response, and fastness.
• Leaving test conditions open. Results cannot be compared reliably when extension, wash, conditioning, or recovery time changes.

Procurement next step

Send the supplier a one-page brief stating the gym-short layer, target composition, GSM and width, fit, color, finish, care cycle, and required tests. Ask for identified swatches and a specification sheet, then approve the fabric only after the garment sample and test conditions match the intended product. ClothFactory can use that brief to compare an existing nylon-spandex or polyester-spandex construction with a development option without treating an unverified performance claim as a finished specification.

For thermal underwear, compare nylon-spandex and polyester-spandex against next-to-skin comfort, moisture conditions, insulation targets, stretch recovery, and the planned care cycle. Fiber composition alone cannot predict warmth or fit; GSM, knit construction, finishing, and test conditions should be approved together before bulk sourcing.

Start with the garment brief

A close-fitting base layer worn under another garment has different requirements from a standalone winter top. Before requesting samples, record the intended climate, layering position, body zones that need coverage, target fit, color range, and wash instructions. These inputs determine whether the priority is a light hand and low bulk, a more stable surface, moisture transfer, or additional insulation.

For example, a brand developing a thin base layer for indoor-to-outdoor commuting may prefer a lower-bulk construction that fits under a sweater. A heavier winter layer may accept more fabric mass if the added coverage and air volume justify it. This is a product brief decision, not a conclusion that one fiber family is universally warmer.

Compare composition without treating it as a performance guarantee

Nylon-spandex and polyester-spandex are both viable starting points for stretch thermal underwear. Use composition to narrow the candidate list, then compare the finished fabric under the same test conditions.

This comparison prevents a common sourcing error: approving a composition name while leaving the construction and acceptance conditions undefined.

Use GSM to estimate garment mass, not to claim warmth

GSM is useful for costing, marker planning, and garment-weight estimates. It is not a standalone thermal rating. Yarn size, loop geometry, thickness, air volume, surface treatment, and garment coverage can change the warmth and moisture behavior of fabrics with similar GSM.

Illustrative calculation — not a ClothFactory test result: if the finished fabric area in a garment is assumed to be 1.2 m², a 180 gsm fabric contributes approximately:

1.2 m² × 180 g/m² = 216 g

A 240 gsm option would contribute approximately 288 g under the same area assumption, a difference of 72 g before seams, trims, cutting waste, and any panels in other materials. Use the calculation to compare garment mass and consumption; verify warmth through the finished construction and garment sample.

Specify knit structure and finishing separately

The same fiber blend can produce very different thermal underwear depending on how it is knitted and finished. Ask the supplier to identify the construction, finished width, GSM, thickness if relevant, and any surface treatment. If a brushed or other thermal finish is proposed, confirm whether it is part of the standard specification or an optional development step.

Finishing may change hand feel, moisture behavior, pilling, color appearance, and dimensional stability. A fabric that feels suitable before washing may not provide the same surface or recovery after the agreed care cycle. Approval should therefore use finished, laundered samples where the end product will be sold with a care label.

Build a comparable sample request

Send the same brief to each candidate supplier. At minimum, request:

• target composition and any permitted tolerance;
• finished GSM range, usable width, and knit construction;
• stretch and recovery requirements by direction, including extension, hold time, and recovery time;
• dimensional stability and spirality after the specified wash procedure;
• pilling, abrasion, colorfastness, and snagging requirements relevant to the end use;
• hand-feel reference, target shade, and whether the finish is required or optional;
• sample identification that links each swatch to its specification sheet.

Do not compare one supplier’s finished GSM with another supplier’s greige GSM, or compare recovery values produced with different extension levels and recovery times. The numbers may look comparable while describing different tests.

Avoid these approval mistakes

• Selecting by blend name alone. A nylon-spandex label does not specify knit density, finish, GSM, or recovery.
• Using GSM as a warmth guarantee. Higher mass may increase coverage or weight without delivering the expected insulation.
• Approving one color for every color. Dye depth and finishing can affect hand, stretch response, and colorfastness; confirm the production shade range separately.
• Treating a fabric test as a garment result. Fit, seam placement, paneling, and laundering can change the wear outcome.
• Leaving the care cycle open. Test conditions should reflect the intended label and the buyer’s quality threshold.

Procurement next step

Prepare a one-page brief with the end use, layering position, target composition, GSM and width, fit intent, shade, finish, care cycle, and required tests. Ask for identified samples and a specification sheet, then approve the fabric only after the construction and test conditions match the product brief. ClothFactory can use that information to compare an existing nylon-spandex or polyester-spandex base fabric with a development option, while keeping any unconfirmed performance requirement open for sampling and verification.

Shortlist a nylon-spandex double-knit with a matte face or a smooth double-sided interlock. Approve the fabric only after checks on a legging sample at the intended fit. Catalogue descriptions help select candidates, but opacity and compression under stretch remain sample decisions.

Candidate Constructions for High-Compression, Four-Way-Stretch Yoga Leggings

Use H2894 Matte Performance Double-Knit as the catalogue matte double-knit reference. The table compares it with a smooth-surfaced interlock and a ribbed option. These are sampling candidates, not interchangeable approvals: the ribbed face suits a different surface brief.

Catalogue parameters and listed features for sampling candidates; features are descriptions, not measured garment results.

Select the knit face before comparing quotes. A flat, matte appearance points toward the double-knit; a sleek surface makes the interlock worth sampling. Keep the ribbed construction only if visible texture is acceptable.

How Weight, Density, and Stretch Conditions Drive Opacity

Catalogue weight describes fabric mass per area. It does not tell a buyer how much coverage remains when the panels stretch across the seat and thigh. Knit structure and the extension imposed by the pattern also affect what the wearer sees. Inspect each candidate over a consistent backing at the extension expected in the intended size and fit. Record the viewing conditions and approve coverage on that basis, including during a squat. A heavier catalogue option may change hand feel or material use without resolving show-through.

Surface Finish: Matching Matte, Smooth, or Ribbed Character to the Design Brief

Use H113 Shark-Skin Double-Sided Interlock as the catalogue smooth-surface comparison. Its description also calls the face shark-skin textured, so compare an actual swatch with the matte double-knit under the lighting used for approval. Check sheen after stretching the panel; a surface that looks suitable at rest may look different on the garment.

Recovery and Compression Trade-Offs Across Candidate Elastane Levels

Catalogue elastane percentages and listed recovery features identify candidates, but they do not establish the pressure or fit of a finished legging. Stretch each sample in both fabric directions, release it, and compare its return with the approved fit target after repeated extensions. Use H3827 LULU High-Stretch Rib Fabric as a catalogue ribbed recovery reference only when that texture fits the design. If the standard constructions miss the target, a supplier development brief can specify the required structure, hand feel, stretch, and recovery.

Sample and Pre-Production Checks Before Bulk Commitment

Set the fit target, backing, lighting, and surface reference when the sample is approved. The same conditions give the factory a clear pre-production comparison. Hold a candidate for adjustment when coverage, recovery, or appearance misses the agreed target; approve bulk only against the accepted fabric and garment sample.

Proposed pre-production checks against the buyer’s agreed legging target; no results are implied.

Cost and MOQ Implications of Each Candidate Construction

Catalogue parameter: the minimum order quantity is 200 KG for each candidate. Catalogue parameters: stated yields are 2.6m/kg for the matte double-knit, 2.7m/kg for the interlock, and 3.0m/kg for the ribbed fabric. These figures do not rank cost per legging. Compare supplier prices and marker consumption on the same pattern, size mix, and quality requirement; usable cutting width and actual fabric use determine the purchase estimate.

Modal is a rayon-family cellulosic fibre known for a soft, breathable handle, but for activewear sets requiring stretch, elastic recovery, quick drying, and body-hugging coverage, a synthetic knit such as a nylon and spandex performance double-knit is the more dependable specification. Modal suits low-intensity lifestyle pieces where softness and airflow outweigh elastic recovery. Keep in mind that fibre-level characteristics always require physical confirmation on the actual garment pattern.

Modal’s Advantages and Drawbacks for Activewear Sets

When evaluating modal for activewear sets, buyers must weigh its natural comfort against mechanical limitations. Modal offers superior heat management and breathability compared to standard polyester. As a cellulosic option, it is stronger and lighter than viscose, making it better suited for garments requiring durability alongside softness. However, modal provides limited elastic recovery on its own and dries slower than engineered synthetic performance knits. Without blending, it cannot support high-movement fit retention.

Modal’s Advantages and Drawbacks for Activewear Sets

How Modal and Synthetic Knits Compare on Stretch, Recovery, and Fit

High-performance activewear sets rely heavily on elongation and fit retention. Synthetic options deliver superior 4-way elastic recovery and compression architecture. For example, a catalogue parameter of 75% nylon and 25% spandex at a 230 GSM weight provides opaque, second-skin coverage and high recovery compression. While blended modal fabrics may add some stretch, they do not inherently match the permanent vertical structure of synthetic double-knits or rib constructions.

Comparing Modal Fibre Profiles to Synthetic Performance Knits

Applying the Choice to Leggings, Tops, and Matching Sets

The garment pattern dictates the final fabric specification. For high-compression leggings and matching sets needing complete coverage and fit retention, specify a synthetic knit like the H2894 Matte Performance Double-Knit or the H3827 LULU High-Stretch Rib Fabric. For premium yoga tops or lightweight lifestyle sets where a silky handfeel is the primary goal, a nylon blend mimicking modal such as the H949 Lyocell-Touch Technical Grid can succeed. Note that drying behaviour and opacity follow the specific knit construction and fabric weight, not the fibre name alone.

Sampling, Approval, and the Selection Rule

Before bulk production, confirm elongation, recovery, drying speed, and coverage by sampling the selected fabric on the actual garment pattern. Use standard test methods to evaluate stretch and recovery rather than relying on supplier reference ranges or fibre reputation alone. The final selection rule is straightforward: specify synthetic performance knits for high-movement, high-fit-retention activewear sets, and reserve modal for low-intensity applications where softness and breathability dictate the purchase.