How to Wash Rayon and Rayon-Spandex: Care Labels Decoded

The short version

• Follow the garment's care label. US rules make its maker or importer responsible for instructions that won't substantially harm it when followed.
• Label words have standard meanings. On a machine-wash label, Cold means water that starts at no more than 86°F.
• We can't give a shrinkage percentage for rayon. For a baseline, measure the garment flat before its first wash.

Start with the care label inside the garment. US rules generally require clothing makers and importers to attach a permanent care label that's easy to find when the item is for sale and stays readable for the garment's useful life (16 CFR 423.1, 16 CFR 423.6).

That label, not a rule of thumb about a fiber, is your guide. Below, we decode its words using the federal Care Labeling Rule's definitions and apply them to a rayon or rayon-spandex knit.

Why the care label is your best guide

The rule puts the work of figuring out care on the people who make or import the garment. The FTC says they must make sure the instructions, if followed, "will cause no substantial harm to the product" (FTC care labeling guide).

A care label has to give either a washing or a drycleaning instruction. If it gives washing, it must say whether to wash by hand or machine, name a water temperature unless regular use of hot water up to 145°F won't harm the item, and say whether to machine dry or use another method. It must give bleach instructions when bleach would cause harm, and warn you when any part of the washing you could reasonably be expected to do would harm the item or others washed with it. The maker also needs a reasonable basis for all of it, such as reliable test results, current technical literature, past experience or industry expertise (16 CFR 423.6(b), (c)).

The fiber line follows a different rule

Under the textile labeling rules, rayon is a manufactured fiber made of regenerated cellulose. Spandex is a manufactured fiber whose fiber-forming substance is a long-chain synthetic polymer made of at least 85% segmented polyurethane (16 CFR 303.7(d), (k)). Labels may instead use the international names viscose for the main form of rayon and elastane for spandex (FTC textile labeling guide).

Fibers are listed by weight, largest first. In general, only fibers that make up 5% or more of the fiber weight are named. A smaller one appears as other fiber unless it has a definite functional significance at that amount, as in the FTC's example of spandex used for elasticity (FTC textile labeling guide). At 5%, spandex is named in any case, so a blend of viscose rayon with 5% spandex can be labeled 95% rayon, 5% spandex or 95% viscose, 5% elastane. The fiber line doesn't tell you how to wash, though. More in our guide to reading a fiber label.

What the words on the label mean

The rule's glossary gives standard meanings for common care terms (16 CFR 423, Appendix A). Temperatures refer to the water at the start of the wash.

• Delicate cycle or Gentle cycle: slow agitation and a shorter wash time.
• Do not wring (machine wash): don't wring by hand or use a roller wringer.
• No wring or twist (hand wash): handle the item so it doesn't wrinkle or lose its shape.
• Wash inside out: turn the item inside out to protect the face, or outer side, of the fabric.

Washing a rayon or rayon-spandex knit, step by step

Each step follows a phrase you may find on the label. If anything here differs from your label, your label wins.

1. Use the method named: Hand wash or Machine wash.
2. Match the water to the word. Machine wash cold means water that starts at no more than 86°F. A machine-wash label that names no temperature is telling you regular use of hot water up to 145°F won't harm the item.
3. Pick the named cycle. Delicate or Gentle means slow agitation and a shorter time.
4. Turn it inside out if asked. Wash inside out is there to protect the outer side of the fabric.
5. Read the bleach line. No bleach means none. Only non-chlorine bleach, when needed rules out chlorine bleach. If a label says nothing about bleach, the rule reads that silence as meaning all commercially available bleaches can safely be used on a regular basis, and the maker needs proof of that (16 CFR 423.6(b)(1)(iv), (c)(1)).
6. Don't wring if told not to. The glossary describes hand washing as a gentle squeezing action and defines No wring or twist as handling the item to avoid wrinkles and distortion. So if your label says it, squeeze gently rather than wringing or twisting.

Drying: tumble dry low, dry flat or line dry

• Tumble dry: use a machine dryer. With no setting named, a hot setting may be used regularly.
• Tumble dry low: set the dryer to low heat.
• Remove promptly: take items out as soon as they're dry, so they don't wrinkle.
• Dry flat: lay the item out horizontally to dry.
• Line dry: hang it damp from a line or bar, indoors or out.

One detail is easy to miss: the rule doesn't require a warning against a method that's simply an alternative to the one on the label. Its own example: a label that says Dry flat doesn't need to add Do not tumble dry (16 CFR 423.6(b)(1)(v)(B)). So if your label says Dry flat or Line dry, don't take the missing warning as permission to use the dryer.

Will it shrink?

We can't give you a percentage, and we won't guess. We haven't found a government or university source with a rayon shrinkage figure we'd stand behind.

What we can point to is how the rule works: the maker needs a reasonable basis for its instructions, and following them must not substantially harm the garment (16 CFR 423.6(c); FTC care labeling guide). Following the label keeps you within what the maker has vouched for. Drying on high when the label says low does not.

For a baseline, measure the garment flat before its first wash and write the numbers down. Our guide to measuring for pajamas shows how to measure a garment you already own. If something seems different after a wash, measure again and compare.

What about pilling?

Pilling isn't covered by the care rule: neither the rule's text nor its glossary mentions it. We can't promise that any washing method keeps it from happening, and we won't explain causes we haven't checked against a reliable source.

The glossary's only reason for Wash inside out is to protect the face of the fabric. It says nothing about pilling, so we don't claim that washing inside out makes a difference to it. If your label says Wash inside out, follow it, along with the rest of the label.

Care symbols

US rules allow symbols from the ASTM system alongside the words or in place of them, as long as the symbols meet the rule's requirements. The current rule text names one standard, ASTM D5489-96c (16 CFR 423.8(g)).

The FTC's guidance on this is from May 2014. It calls symbols optional when care instructions are on the label and says ISO symbols weren't allowed then (FTC care labeling guide). We haven't reviewed the ASTM standard itself, so we don't decode individual symbols here. When your label has words, trust the words.

Quick reference

Definitions: 16 CFR 423, Appendix A.

This article is general information, not medical advice. Talk with your healthcare provider about symptoms and treatment options.

Sources (accessed 2026-10-17)

• Federal Trade Commission. Clothes Captioning: Complying with the Care Labeling Rule. May 2014.
• Electronic Code of Federal Regulations. 16 CFR Part 423, Care Labeling of Textile Wearing Apparel and Certain Piece Goods, including Appendix A, Glossary of Standard Terms. Current as of 2026-10-15.
• Federal Trade Commission. Threading Your Way Through the Labeling Requirements Under the Textile and Wool Acts. Edited October 2020 and January 2025.
• Electronic Code of Federal Regulations. 16 CFR 303.7, Generic names and definitions for manufactured fibers. Current as of 2026-10-15.

Shop our sleepwear