How Do You Judge the Spandex in Nylon Spandex Fabric? Recovery, Chlorine and Heat Tests to Ask About

Short answer: The spandex (elastane, 氨纶) in nylon spandex fabric is judged mainly on recovery, chlorine resistance and heat resistance, and each has a Chinese textile industry test method: FZ/T 50006-2013 for tensile properties, FZ/T 50007-2012 for elasticity, and FZ/T 50033-2016 and FZ/T 50034-2016 for heat and chlorine resistance of spandex filament. What buyers can do is ask which standard a report follows and whether it tested the yarn or the fabric; results are determined by the report.

Maoxing Textile Dyeing has been making nylon spandex fabric at Zhongda, Guangzhou for 15 years. This article covers only how to judge the spandex itself and which tests to ask about; care and swimwear sampling are covered in earlier articles.

How to care for nylon spandex fabric What to ask when requesting nylon spandex swimwear fabric samples

Which test methods relate to spandex?

Four textile industry standards cover spandex directly, and two national standards cover fabric color in chlorinated water and care labels.

The first four test spandex yarn; the last two apply to fabric and labels. Check which level a report covers: yarn results and fabric results cannot stand in for each other.

Which test should you ask about for spandex recovery?

Ask whether the report follows FZ/T 50007-2012 for elasticity, and FZ/T 50006-2013 for tensile properties. Both are test methods for spandex yarn, so they describe the raw yarn.

Ask the supplier whether the spandex yarn has reports under these standards, and whether the report came from the yarn producer or the fabric supplier's own submission. We give no recovery values; results are determined by the report. For the finished fabric, stretch the swatch in both directions and watch it recover.

How to sample nylon spandex fabric

Which test should you ask about for spandex chlorine resistance?

For spandex filament, ask about FZ/T 50034-2016; for fabric color in pool water, ask about GB/T 8433-2013. They test different things: FZ/T 50034-2016 covers the chlorine resistance of spandex filament, while GB/T 8433-2013 measures how textile color holds up to active chlorine in pool water.

For swimwear, ask about both: a chlorine report for the yarn and a chlorinated water fastness report for the fabric. We give no chlorine values; the standard and report conclusion decide.

How to check colorfastness on nylon elastane fabric

Which test should you ask about for spandex heat resistance?

For spandex filament, ask about FZ/T 50033-2016. The nylon component also has limited heat resistance and lightfastness, so consider heat at both the yarn and fabric level.

Whether and how a garment can be ironed is shown on the care label. Under GB/T 8685-2008, the dots in the iron symbol indicate the upper limit of the soleplate temperature; follow the symbol. We do not give specific temperatures.

How do bleaching symbols on care labels relate to spandex?

The bleaching symbol tells consumers whether chlorine bleach may be used, which matters for garments containing spandex. GB/T 8685-2008 has three bleaching symbols: any bleaching agent allowed, only oxygen/non-chlorine bleach allowed, and do not bleach.

When checking care labels, make sure the bleaching and ironing symbols agree with the fabric's chlorine and heat reports.

What should you check first on spandex-related reports?

Check the tested object and standard number first, then the results.

1. Whether it tested spandex yarn, spandex filament or fabric.
2. Whether the standard number and year are correct, e.g. FZ/T 50007-2012 for elasticity.
3. Whether the report's batch matches your swatch.
4. Whether results and conclusions meet your end use and customer requirements.

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FAQ

What if the supplier has no spandex yarn report?

Ask for the yarn producer's report, or rely on fabric-level reports. For fabric color in pool water, use GB/T 8433-2013; without yarn reports for recovery, chlorine or heat, rely on swatch checks and later testing.

Does a spandex yarn report represent the whole fabric?

Not directly. FZ/T 50006, 50007, 50033 and 50034 test spandex yarn or filament; the fabric also depends on the nylon, knit structure and dyeing and finishing, so check fabric reports and swatches separately.

Which two spandex-related reports matter for swimwear?

The FZ/T 50034-2016 spandex filament chlorine report and the GB/T 8433-2013 fabric chlorinated water fastness report. One covers the yarn, the other the fabric color.

Can the care label say any bleach is allowed?

It depends on the report. GB/T 8685-2008 has three bleaching symbols; choose the one that matches the fabric's chlorine performance.

Sources

1. FZ/T 50006-2013 (tensile properties of spandex yarn), FZ/T 50007-2012 (elasticity of spandex yarn), FZ/T 50033-2016 and FZ/T 50034-2016 (heat / chlorine resistance of spandex filament). China Chemical Fibers Association, list of current industry standards, https://www.ccfa.com.cn/33/202305/1504.html , checked 2026-11-02.
2. GB/T 8433-2013, Textiles - Tests for colour fastness - Colour fastness to chlorinated water (swimming-pool water), National Public Service Platform for Standards Information, https://std.samr.gov.cn/gb/search/gbDetailed?id=71F772D7EEF0D3A7E05397BE0A0AB82A , current.
3. GB/T 8685-2008, Textiles - Care labelling code using symbols (three bleaching symbols; meaning of iron dots), https://std.samr.gov.cn/gb/search/gbDetailed?id=71F772D77659D3A7E05397BE0A0AB82A , current.
4. Nylon's poor heat and light resistance. China Cotton Textile Association, textile knowledge, http://www.ccta.org.cn/fszz/fzzsxx/rs/202104/t20210429_4136415.html , checked 2026-10-26.

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Nylon spandex stretch fabrics Stall 16-18, North 5th Street, Zhongda Jiangnan Textile City, Haizhu District, Guangzhou WhatsApp: +86 15918964057