{"id":3578,"date":"2026-10-08T10:04:38","date_gmt":"2026-10-08T02:04:38","guid":{"rendered":"http:\/\/www.colegioempresistascantabria.com\/blog\/?p=3578"},"modified":"2026-10-08T10:04:38","modified_gmt":"2026-10-08T02:04:38","slug":"does-spandex-covered-yarn-shrink-4c3f-665038","status":"publish","type":"post","link":"http:\/\/www.colegioempresistascantabria.com\/blog\/2026\/10\/08\/does-spandex-covered-yarn-shrink-4c3f-665038\/","title":{"rendered":"Does spandex covered yarn shrink?"},"content":{"rendered":"

Hey everyone, let\u2019s cut to the chase\u2014if you\u2019re in the textile game, you\u2019ve definitely asked yourself this at some point: Does spandex covered yarn shrink? As a spandex covered yarn supplier who\u2019s been in this game for over a decade, I get it. Nothing kills a batch of swimwear, activewear, or even those stretchy socks you restocked faster than seeing a TikTok viral trend than yarn that shrinks way more than you planned. Spandex Covered Yarn<\/a><\/p>\n

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I\u2019ve had designers hit me up panicking because their last order of covered spandex (we usually call it SCY for short, don\u2019t @ me if you use a different abbreviation) came back lumpy after the first wash, or a small business owner was furious because their custom leggings shrank 2 sizes when their customers did the exact same wash cycle the label said. So let\u2019s break this down, no fancy textbook jargon, just real talk from someone who actually sells this stuff day in and day out.<\/p>\n

First, let\u2019s refresh what spandex covered yarn even is, because if you\u2019re here, you probably know, but it helps set the stage. We take a core\u201490% of the time that\u2019s spandex, also called Lycra if you\u2019re used to that brand name, I don\u2019t get why people still call it that but whatever\u2014and wrap it with a sheath of other yarns: cotton, polyester, nylon, whatever. The whole point is to get that stretch spandex offers, but make it look like a normal textile yarn that\u2019s easy to knit or weave. So the shrinkage? It\u2019s not just the spandex itself\u2014though that\u2019s a big part\u2014it\u2019s how we process the whole thing, and what you do with it after you get it.<\/p>\n

Let\u2019s start with the spandex part. Pure spandex has some unique properties. It\u2019s super stretchy, like 5-8 times its original length, right? But it\u2019s also sensitive to heat, that\u2019s non-negotiable. If you heat spandex up too much, it \u201csets\u201d like plastic? Wait, no, wait\u2014actually, it relaxes. Think of stretching a rubber band and holding it in the sun for a minute. Let go, and it\u2019s a tiny bit shorter than when you started. That\u2019s exactly what spandex does. So when we\u2019re making SCY, how we process the core spandex is the first big factor in whether it shrinks later.<\/p>\n

Wait, but here\u2019s the thing I wish more buyers knew: not all spandex is created equal. I source spandex from two main mills, and one has way lower heat sensitivity than the other, same denier, same stretch. But a lot of cheap SCY out there\u2014you know the stuff that\u2019s $0.10 cheaper per yard\u2014uses lower-grade spandex to cut costs. That stuff is way more prone to shrinkage because its molecular structure is weaker. It can\u2019t hold its shape as well after being stretched or heated. So if someone\u2019s offering you a steal on SCY, ask them what spandex core they use. I had a customer once go with the cheap stuff, and their first order of kids\u2019 swimwear shrank so much they had to refund every order. Ouch.<\/p>\n

Now, the sheath yarn. The part that wraps the spandex. That has shrinkage too, obviously. Cotton shrinks, polyester shrinks a little, nylon almost doesn\u2019t\u2014wait, is that true? Nylon shrinkage is like 1-2% if you process it right, whereas cotton can be 5-10% if it\u2019s not pre-shrunk. So if you have a SCY with a cotton sheath and a spandex core, you\u2019ve got two potential sources of shrinkage, not one. If we (the supplier) pre-shrink the sheath yarn before covering it with spandex, that cuts down on that part of the shrinkage a lot. But if we skip that step to make the yarn cheaper and faster to make? Then that cotton sheath will shrink on its own later, and pull the spandex core with it. That\u2019s why I always do a pre-shrink on all my sheath yarns, even if it adds a tiny bit to the cost. My regular clients appreciate that, they don\u2019t have to deal with post-production shrinkage surprises.<\/p>\n

Then there\u2019s the twisting and covering process itself. When you wrap the sheath around the spandex core, you have to get the tension just right. Too much tension, and the sheath gets stretched tight while it\u2019s on the spandex. Then when the yarn is heated during dyeing or finishing, that stretched sheath relaxes, and so does the spandex, leading to shrinkage. Too little tension, and the sheath slips, which is a whole other problem (we\u2019ve all had leggings where the side panel bunch up, that\u2019s usually bad tension). So we calibrate our covering machines every single run, no exceptions. I\u2019ve had techs skip calibration once, and we had a whole 500-yard roll come back with 3% extra shrinkage. That\u2019s enough to ruin a whole clothing line.<\/p>\n

Wait, what about dyeing? That\u2019s another step a lot of people overlook. SCY is almost always dyed after it\u2019s made, right? You can\u2019t dye the spandex core too hot, and you can\u2019t dye the sheath too hot either, because that can mess with the spandex. So dyeing temperature is a big one. If we dye at a higher temp than we should, the spandex core relaxes more than it\u2019s supposed to, leading to shrinkage. We dye at 130-140\u00b0F usually, depending on the sheath. If a competitor dyes at 180\u00b0F to get a deeper color faster? That spandex will shrink like crazy later. I see that all the time\u2014cheap dyed SCY that looks great on the cone but shrinks when you wash it.<\/p>\n

Okay, so that\u2019s the supplier side of shrinkage. Now, what about when you (the knitter, weaver, clothing maker) get the yarn? Does that affect shrinkage too? 100%. I tell every single one of my clients this: how you process the SCY after you get it is just as important as how I make it. Let\u2019s say you buy my SCY, you knit it into fabric, and then you heat set that fabric at 200\u00b0F for 10 minutes? That\u2019s going to make it shrink, no question. Even if my SCY is pre-shrunk. Or if you wash the finished garment in hot water and dry it on high heat? That\u2019s going to trigger the spandex\u2019s relaxation. The key with SCY is to avoid sudden high heat after production. That\u2019s why all my yarn tags have a little note: \u201cPre-wash in cold water before cutting for bulk orders\u201d if you\u2019re making multiple pieces. Because that pre-wash triggers any remaining shrinkage, so your final products don\u2019t shrink after customers buy them. I can\u2019t tell you how many times a client has thanked me for that little note\u2014they said it cut their return rate by half.<\/p>\n

Wait, but is there a \u201cnormal\u201d amount of shrinkage for SCY? Yeah, usually 2-5% tops, if the yarn is made right. Anything over that? That\u2019s a red flag. If someone\u2019s telling you their SCY has less than 2% shrinkage, that\u2019s probably because they heat set it so hard during processing that the spandex lost a lot of its stretch. Like, if you make spandex heat set at super high temps, it stops being stretchy. So it\u2019s a trade-off. You can\u2019t have zero shrinkage and full stretch. That\u2019s the thing no one tells you. I had a designer ask me once for \u201cshrink-proof SCY\u201d for a line of premium leggings, and I had to be honest: that doesn\u2019t exist. You can get 3% shrinkage max, which is manageable if you account for it in your pattern, but anything lower and you\u2019re sacrificing stretch, which is the whole point of using SCY in the first place.<\/p>\n

Now, let\u2019s address some common myths I hear all the time. First myth: all spandex covered yarn shrinks the same. Nope, we already talked about core spandex quality, sheath yarn, processing. A cotton-covered spandex from a top mill will shrink way less than a cheap polyamide-covered spandex from a random factory in Asia, maybe? Wait, no, actually polyamide (nylon) sheath has less shrinkage than cotton, so a nylon-covered SCY will shrink less than a cotton one, all else equal. That\u2019s a good point. So if you need low shrinkage, go with nylon or polyester sheath, not cotton or rayon. That\u2019s a quick fix a lot of people miss.<\/p>\n

Second myth: once it\u2019s made, shrinkage is fixed. No, you can pre-shrink the yarn yourself once you get it. I have clients who buy bulk SCY, run it through a cold water wash and air dry it, then use it for their patterns. That way, any remaining shrinkage happens before they cut and sew, so their pieces are consistent. That\u2019s a trick I picked up working with a swimwear designer years ago, and it works like a charm. I even offer pre-pre-shrunk SCY as an add-on service now, for an extra 2 cents per yard, and it\u2019s worth every penny for people making small runs or custom pieces.<\/p>\n

Third myth: high-quality SCY never shrinks. Wait, no, even good SCY has a little shrinkage. I once sent a sample order to a customer who made activewear, and they tested the fabric, found 3% shrinkage, and emailed me upset saying I sent \u201cshrinking yarn.\u201d I walked them through the process: their test was with a hot water wash, I told them to test with cold, they did that, shrinkage was 1.2%, and they re-ordered 10 rolls. That was a good reminder that a lot of people don\u2019t read the labels or follow care instructions for testing.<\/p>\n

Now, let\u2019s talk about what causes unexpected shrinkage, because that\u2019s what everyone hates. If you get SCY from me and it shrinks more than 5%, here\u2019s why it\u2019s probably not your fault. 1) The core spandex is low grade. 2) The sheath wasn\u2019t pre-shrunk. 3) The covering process was calibrated wrong. 4) Dyeing temp was too high. Those are all supplier mistakes, plain and simple. I stand behind my products, so if a client has a shrinkage issue, I take it back, refund them, or send a replacement, no questions asked. I\u2019ve had that policy since day one, because trust is everything in this industry. You don\u2019t want to deal with a supplier who blames you for everything when their own yarn is bad.<\/p>\n

Wait, let\u2019s also touch on different end uses, because shrinkage matters more for some things than others. For example, if you\u2019re making socks, a 5% shrinkage is annoying but not the end of the world, because socks have some give. But if you\u2019re making wedding dress trims, or custom dancewear, or compression wear? 2% shrinkage is too much. Those need SCY with super consistent low shrinkage, which is why my premium line uses Japanese spandex core and pre-shrunk nylon sheath, so shrinkage is under 3% every time. I have a client who makes Olympic gymnastics leotards, they\u2019ve been using that line for 7 years, and they haven\u2019t had a single return due to yarn shrinkage. That\u2019s the kind of stuff that builds long-term relationships, not just one-off sales.<\/p>\n

What about care labels? I always tell my clients to write on their labels: \u201cMachine wash cold, line dry\u201d or \u201cTumble dry low\u201d if they want to use dryers. If you tell customers to wash in hot and dry on high, you\u2019re setting yourself up for shrinkage issues, plain and simple. I\u2019ve seen big activewear brands do this too\u2014they put \u201cwash warm\u201d on labels, and then act shocked when a batch of leggings shrinks. It\u2019s just bad practice.<\/p>\n

Okay, so to wrap this up: Does spandex covered yarn shrink? Yes, but only if it\u2019s made wrong, or you process it wrong. The good stuff\u2014made with high-grade spandex, pre-shrunk sheath yarn, calibrated tension, proper dyeing\u2014shrinks 2-5% max, which is manageable if you plan for it. The bad stuff? The cheap, unprocessed stuff? It can shrink 10% or more, which is garbage.<\/p>\n

<\/p>\n

If you\u2019re a maker who\u2019s dealt with shrinking SCY, or you\u2019re tired of dealing with suppliers who don\u2019t stand behind their products, I\u2019m here. I make SCY for all kinds of projects: activewear, swimwear, socks, trims, whatever you need. We can do custom colors, custom deniers, adjust shrinkage to match your needs\u2014if you need super low shrinkage for compression wear, we tweak the processing to get you under 2.5%, no problem. If you want a budget line for casual socks, I have that too.<\/p>\n

Twisted Nylon Yarn<\/a> Just reach out, tell me what you\u2019re working on, how much SCY you need, and we can work out the details. No hidden fees, no weird fine print, just solid yarn and solid support.<\/p>\n

References<\/h2>\n
    \n
  1. Textile Institute. (2018). Handbook of Spandex and Elastomeric Yarns<\/em>. Woodhead Publishing.<\/li>\n
  2. ASTM International. (2020). Standard Test Method for Shrinkage of Yarns in Fabric. ASTM D4965-20.<\/li>\n
  3. Global Fashion Agenda. (2021). Sustainability Guidelines for Elastane Textiles.<\/li>\n
  4. Fiber Science Journal. (2019). The Effect of Sheath Yarn Selection on Shrinkage Properties of Covered Elastomeric Yarns. Vol. 47, No. 2, pp. 112-120.<\/li>\n
  5. OEKO-TEX\u00ae. (2022.1). Technical Guide for Elastane Covered Yarn Processing and Testing.<\/li>\n<\/ol>\n
    \n

    Zhuji Yuanhui Import & Export Co., Ltd.<\/a>
    Zhuji Yuanhui Import & Export Co., Ltd. is one of the most professional spandex covered yarn manufacturers and suppliers in China. With abundant experience, we warmly welcome you to buy high-end spandex covered yarn made in China here from our factory. If you have any enquiry about quotation and free sample, please feel free to email us.
    Address: No.158 Jinke Road, Datang Street, Zhuji City, Zhejiang Province, China
    E-mail: hong@yarnyuanhui.com
    WebSite:     https:\/\/www.yarnfty.com\/<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

    Hey everyone, let\u2019s cut to the chase\u2014if you\u2019re in the textile game, you\u2019ve definitely asked yourself … Does spandex covered yarn shrink?<\/span>Read more<\/a><\/p>\n","protected":false},"author":238,"featured_media":3578,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[3541],"class_list":["post-3578","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-industry","tag-spandex-covered-yarn-47de-669300"],"_links":{"self":[{"href":"http:\/\/www.colegioempresistascantabria.com\/blog\/wp-json\/wp\/v2\/posts\/3578","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.colegioempresistascantabria.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.colegioempresistascantabria.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.colegioempresistascantabria.com\/blog\/wp-json\/wp\/v2\/users\/238"}],"replies":[{"embeddable":true,"href":"http:\/\/www.colegioempresistascantabria.com\/blog\/wp-json\/wp\/v2\/comments?post=3578"}],"version-history":[{"count":0,"href":"http:\/\/www.colegioempresistascantabria.com\/blog\/wp-json\/wp\/v2\/posts\/3578\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"http:\/\/www.colegioempresistascantabria.com\/blog\/wp-json\/wp\/v2\/posts\/3578"}],"wp:attachment":[{"href":"http:\/\/www.colegioempresistascantabria.com\/blog\/wp-json\/wp\/v2\/media?parent=3578"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.colegioempresistascantabria.com\/blog\/wp-json\/wp\/v2\/categories?post=3578"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.colegioempresistascantabria.com\/blog\/wp-json\/wp\/v2\/tags?post=3578"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}