About Must Be Cotton

Must Be Cotton exists for one kind of shopper: the person who wants something to be cotton, all of it, and is tired of finding polyester, spandex or a rubber waistband hiding behind the word “cotton.”

Our mission

We publish practical, sourced guides to bedding, towels, clothing, baby items and home textiles that are genuinely 100% cotton. We explain how to read labels and certifications so you can check things yourself, and we only recommend products that pass the strict test below.

We are independent. Brands don’t pay to be included, can’t buy a better spot, and don’t see articles before they’re published. Some links on the site are affiliate links; here’s how that works.

Who’s behind it

Must Be Cotton is run by its founder and editor, Peter Martin. Peter sets the site’s strict all-cotton rule and reviews and approves every guide before it’s published.

Editor: Peter Martin

How we verify fiber content

Our rule: every textile part of a product must be 100% cotton. That means the main fabric, the sewing thread, any elastic, labels, piping, binding and other trims. No exceptions and no blends.

Elastic is where most “cotton” products fail. We exclude anything with spandex/elastane, nylon, polyester, natural rubber, latex or “plant-based” elastic, even if the fabric itself is 100% cotton. We only list styles with no elastic at all (for example flat sheets, tie-closure or drawstring designs) or elastic that the brand confirms is entirely cotton.

Thread counts too. Products sewn with polyester thread, or with polyester-core (“corespun,” cotton-wrapped polyester) thread, are excluded. The thread has to be cotton all the way through, and we ask brands to confirm it, because US labels don’t have to mention thread.

Buttons and closures. Hardware isn’t fiber, so it can’t be “cotton.” Natural coconut-shell and nut buttons (such as tagua, also sold as corozo) are allowed. Every product card has a “Closures” line that names exactly what a product uses, or says “None.”

The checks we run before a product is listed

Read the legal fiber label. In the US, the label must list each fiber by its generic name and percentage by weight. We look for “100% cotton” or “All cotton,” and for qualifiers like “exclusive of elastic” or “exclusive of decoration,” which tell us parts were left out. (FTC labeling guidance)
Check every part the label is allowed to skip. US rules exempt sewing thread, trims and some elastic from the fiber statement, so a legal “100% cotton” label can still sit on a product sewn with polyester thread. We look for the brand’s own statement on thread, elastic and trims, and ask in writing when it isn’t published.
Verify certifications at the source. We check GOTS claims in the GOTS public database, OEKO-TEX labels in the OEKO-TEX Label Check, and OCS claims in Textile Exchange’s certified-company search. A certificate number that doesn’t check out disqualifies the claim.
Record what we found, and when. Every product card lists fiber, thread, elastic, other trims, closures and certifications, plus the date we last checked. If a brand can’t or won’t confirm a part, the product isn’t listed.
Re-check regularly. Brands change suppliers. We re-check facts and prices on a rolling monthly schedule and update the “last checked” date. If a product stops meeting the rule, it comes off the page.
Hands-on testing, when we say so. When an article says we tested something, we bought or received it, used it and washed it. We never call an article a “review” without hands-on use.

What we don’t do

We don’t list blends, even good ones, as “picks.” They may appear only as clearly labeled comparisons.
We don’t make health claims we can’t source. Where we discuss research, we link to it and say how strong it is.
We don’t accept payment for placement or positive coverage.

Corrections

If you find an error, or a brand changes a material, tell us. We fix mistakes quickly and note meaningful changes on the page.