“Leading” is not something you can verify from a website. What you can check is whether a manufacturer is right for your product: it has made similar styles in similar fabrics, it has the machines those styles need, it can show test results on bulk fabric rather than on a sample, and it is careful about performance claims such as moisture-wicking, UV protection or anti-odour. The sections below turn that into questions you can ask before you pay a deposit.
Match the factory to the product
Sportswear covers very different products. A factory that makes good training tees may not be ready for compression leggings or swimwear.
| Product | Typical fabric | Construction to look for | Key checks |
|---|---|---|---|
| Leggings and shorts | Nylon or polyester with elastane | Flatlock or coverstitch seams, gusset, wide waistband, sometimes silicone grippers | Stretch and recovery, opacity when squatting, waistband roll |
| Sports bras | Nylon or polyester with elastane, power mesh | Elastic bands, cup pockets or moulded cups, bound edges | Support after washing, chafing at seams and edges |
| Compression tops | High-elastane knits | Close-to-body patterns graded by body measurement | Pressure and fit across sizes, seam strength |
| Training tees and tanks | Polyester or poly-cotton jersey, mesh panels | Standard cut and sew, often heat transfers or sublimation | Shrinkage, pilling, colour fastness to sweat |
| Team jerseys | Polyester knits | Sublimation printing, cut and sew after printing | Print colour accuracy, names and numbers, size range |
| Swimwear | Nylon or polyester with elastane | Lined panels, elastic edges | Colour fastness to chlorinated water, elastic durability |
Ask which of these processes are done in house and which are sent out. Sublimation, bonding, laser cutting and some printing are often subcontracted. That is normal, but you should know where the work happens and who checks it.
Fabric performance: ask for test results, not adjectives
Words such as “breathable” or “high-performance” mean little without a method and a result. Agree the methods in your specification and ask for results on the bulk fabric lot.
| Property | Common test methods | What it tells you |
|---|---|---|
| Stretch and growth | ASTM D2594 (knits with low-power stretch) | How far the fabric stretches under a set load and how much it fails to recover. ASTM notes the method is not recommended for acceptance testing of commercial shipments because results vary between labs, so use it to compare and develop fabrics. |
| Moisture management | AATCC TM195 | How liquid moves into and through the fabric; the basis for any wicking claim |
| Colour fastness to perspiration | ISO 105-E04 | Whether colour changes or stains other fabrics when exposed to sweat |
| Colour fastness to chlorinated water | ISO 105-E03 | Important for swimwear |
| Pilling | ISO 12945-2 | Surface fuzz and pills from rubbing, for example between the thighs |
| Dimensional change | ISO 6330 with ISO 5077, or AATCC TM135 | Shrinkage or growth after home laundering |
| UV protection (if claimed) | AATCC TM183, labelled to ASTM D6603 | The ultraviolet protection factor (UPF) and how it may be labelled |
Related guides: what makes fabric moisture-wicking, four-way stretch and how to test it, leggings that turn see-through and flatlock or overlock seams.
Be careful with performance claims
- Anti-odour and antimicrobial. In the U.S., EPA explains that an article treated with an antimicrobial to protect the article itself can be exempt from pesticide registration, but claims may only describe protecting the product, not protecting the wearer from germs. Ask the factory which treatment is used and whether it is registered for that use (see what an anti-odour gym tee can claim).
- UV protection. If you print a UPF rating, base it on a test such as AATCC TM183 and follow a labelling standard such as ASTM D6603 (see what a UPF 50+ label must show).
- Recycled content. The FTC Green Guides (16 CFR 260.13) require recycled claims to be supportable and qualified when a product is only partly recycled. Ask for transaction certificates or other documents before you print the claim (see recycled polyester claims).
Questions to ask before you choose
- Which products similar to ours have you made, and can we see or buy samples of them?
- Which fabric mills do you use for these fabrics, and can you share recent test reports for the actual fabric quality we would order?
- Which processes are done in your own factory and which are subcontracted?
- How do you grade patterns for close-fitting styles, and which size range have you made before (see sportswear sizing and size curves)?
- What are the minimums per style and per colour, the sample rounds and the bulk lead time?
- How do you inspect seams, stretch and colour before shipment?
Warning signs
- Claims of patents or proprietary technology with no patent number or document you can check.
- Certificates or test reports issued to a different company, or for a different fabric from the one you are buying.
- Every performance claim available on every fabric, with no test methods named.
- A quote far below others for the same specification (see what to check when a quote is much lower).
For a deeper checklist on close-fitting products, see choosing a compression apparel factory and yoga wear factory selection.
Sportswear at Knitwear Base
We make knitted sportswear, including compression clothing, yoga wear and training tops such as our compression shirt. Send your styles, target fabrics and the claims you want to make through our contact page, and ask us which tests we can arrange on the bulk fabric. More activewear questions are answered in Activewear and Compression.
FAQ
Do I need a specialist sportswear factory for simple gym tees?
Not always. A good knit factory can make polyester or poly-cotton training tees. Specialist experience matters more for high-stretch products such as leggings, sports bras, compression wear and swimwear.
Sources and further reading
- ASTM D2594/D2594M, Stretch Properties of Knitted Fabrics Having Low Power
- AATCC TM195, Liquid Moisture Management Properties of Textile Fabrics
- ISO 105-E04:2013, Colour fastness to perspiration
- ISO 105-E03:2010, Colour fastness to chlorinated water (swimming-pool water)
- ISO 12945-2:2020, Fabric propensity to surface pilling, fuzzing or matting: modified Martindale method
- ISO 6330:2021, Domestic washing and drying procedures for textile testing
- ISO 5077:2007, Determination of dimensional change in washing and drying
- AATCC TM135, Dimensional Changes of Fabrics after Home Laundering
- AATCC TM183, Transmittance or Blocking of Erythemally Weighted Ultraviolet Radiation through Fabrics
- ASTM D6603, Standard Specification for Labeling of UV-Protective Textiles
- U.S. EPA, Consumer Products Treated with Pesticides (treated articles exemption)
- eCFR, 16 CFR 260.13, FTC Green Guides: recycled content claims
Rules and standards are summarised from their official pages for general guidance; this is not legal advice. Check the current version and the requirements of your own market before you rely on them.
